feat: expose hash, poseidon_hash and delete_leaf

Co-authored-by: tyshkor <tyshko1@gmail.com>

.github/workflows/ci.yml

@@ -46,10 +46,9 @@ jobs:
           profile: minimal
           toolchain: stable
           override: true
-      - name: Update git submodules
-        run: git submodule update --init --recursive
-      - name: Install cargo-make
-        run: cargo install cargo-make
+      - uses: Swatinem/rust-cache@v2
+      - name: Install dependencies
+        run: make installdeps
       - name: cargo-make test
         run: |
             cargo make test --release
@@ -72,10 +71,9 @@ jobs:
           profile: minimal
           toolchain: stable
           override: true
-      - name: Update git submodules
-        run: git submodule update --init --recursive
-      - name: Install cargo-make
-        run: cargo install cargo-make
+      - uses: Swatinem/rust-cache@v2
+      - name: Install Dependencies
+        run: make installdeps
       - name: cargo-make test
         run: |
             cargo make test --release
@@ -97,10 +95,11 @@ jobs:
           profile: minimal
           toolchain: stable
           override: true
-      - run: git submodule update --init --recursive
+      - uses: Swatinem/rust-cache@v2
+      - name: Install Dependencies
+        run: make installdeps
       - name: Install wasm-pack
         uses: jetli/wasm-pack-action@v0.3.0
-      - run: cargo install cargo-make
       - run: cargo make build
         working-directory: rln-wasm
       - run: cargo-make test
@@ -123,10 +122,9 @@ jobs:
           profile: minimal
           toolchain: stable
           override: true
-      - name: Update git submodules
-        run: git submodule update --init --recursive
-      - name: Install cargo-make
-        run: cargo install cargo-make
+      - uses: Swatinem/rust-cache@v2
+      - name: Install Dependencies
+        run: make installdeps
       - name: cargo-make test
         run: |
             cargo make test --release
@@ -149,10 +147,9 @@ jobs:
           profile: minimal
           toolchain: stable
           override: true
-      - name: Update git submodules
-        run: git submodule update --init --recursive
-      - name: Install cargo-make
-        run: cargo install cargo-make
+      - uses: Swatinem/rust-cache@v2
+      - name: Install Dependencies
+        run: make installdeps
       - name: cargo-make test
         run: |
             cargo make test --release
@@ -177,30 +174,31 @@ jobs:
           toolchain: stable
           override: true
           components: rustfmt, clippy
-      - name: Update git submodules
-        run: git submodule update --init --recursive
+      - uses: Swatinem/rust-cache@v2
+      - name: Install Dependencies
+        run: make installdeps
       - name: cargo fmt
         if: success() || failure()
         run: cargo fmt --all -- --check
       - name: multiplier - cargo clippy
         if: success() || failure()
         run: |
-            cargo clippy --release
+            cargo clippy --release -- -D warnings
         working-directory: multiplier
       - name: semaphore - cargo clippy
         if: success() || failure()
         run: |
-            cargo clippy --release
+            cargo clippy --release -- -D warnings
         working-directory: semaphore
       - name: rln - cargo clippy
         if: success() || failure()
         run: |
-            cargo clippy --release
+            cargo clippy --release -- -D warnings
         working-directory: rln
       - name: utils - cargo clippy
         if: success() || failure()
         run: |
-            cargo clippy --release
+            cargo clippy --release -- -D warnings
         working-directory: utils
         # We skip clippy on rln-wasm, since wasm target is managed by cargo make
         # Currently not treating warnings as error, too noisy

.github/workflows/nightly-release.yml

@@ -6,6 +6,12 @@ on:
 
 jobs:
   linux:
+    strategy:
+      matrix:
+        target: 
+          - x86_64-unknown-linux-gnu
+          - aarch64-unknown-linux-gnu
+          - i686-unknown-linux-gnu
     name: Linux build
     runs-on: ubuntu-latest
     steps:
@@ -17,50 +23,57 @@ jobs:
           profile: minimal
           toolchain: stable
           override: true
-      - name: Update git submodules
-        run: git submodule update --init --recursive
-      - name: cargo build
+          target: ${{ matrix.target }}
+      - uses: Swatinem/rust-cache@v2
+      - name: Install dependencies
+        run: make installdeps
+      - name: cross build
         run: |
-          cargo build --release --workspace --exclude rln-wasm
+          cross build --release --target ${{ matrix.target }} --workspace --exclude rln-wasm
           mkdir release
-          cp target/release/librln* release/
-          tar -czvf linux-rln.tar.gz release/
+          cp target/${{ matrix.target }}/release/librln* release/
+          tar -czvf ${{ matrix.target }}-rln.tar.gz release/
 
       - name: Upload archive artifact
         uses: actions/upload-artifact@v2
         with:
-          name: linux-archive
-          path: linux-rln.tar.gz
+          name: ${{ matrix.target }}-archive
+          path: ${{ matrix.target }}-rln.tar.gz
           retention-days: 2
 
   macos:
     name: MacOS build
     runs-on: macos-latest
+    strategy:
+      matrix:
+        target: 
+          - x86_64-apple-darwin
+          - aarch64-apple-darwin
     steps:
       - name: Checkout sources
         uses: actions/checkout@v2
-        with:
-          ref: master
       - name: Install stable toolchain
         uses: actions-rs/toolchain@v1
         with:
           profile: minimal
           toolchain: stable
           override: true
-      - name: Update git submodules
-        run: git submodule update --init --recursive
-      - name: cargo build
+          target: ${{ matrix.target }}
+      - uses: Swatinem/rust-cache@v2
+      - name: Install dependencies
+        run: make installdeps
+      - name: cross build
         run: |
-          cargo build --release --workspace --exclude rln-wasm
+          cross build --release --target ${{ matrix.target }} --workspace --exclude rln-wasm
           mkdir release
-          cp target/release/librln* release/
-          tar -czvf macos-rln.tar.gz release/
+          cp target/${{ matrix.target }}/release/librln* release/
+          tar -czvf ${{ matrix.target }}-rln.tar.gz release/
 
       - name: Upload archive artifact
         uses: actions/upload-artifact@v2
         with:
-          name: macos-archive
-          path: macos-rln.tar.gz
+          name: ${{ matrix.target }}-archive
+          path: ${{ matrix.target }}-rln.tar.gz
           retention-days: 2
   
   browser-rln-wasm:
@@ -69,22 +82,20 @@ jobs:
     steps:
       - name: Checkout sources
         uses: actions/checkout@v2
-        with:
-          ref: master
       - name: Install stable toolchain
         uses: actions-rs/toolchain@v1
         with:
           profile: minimal
           toolchain: stable
           override: true
-      - run: git submodule update --init --recursive
+      - uses: Swatinem/rust-cache@v2
+      - name: Install dependencies
+        run: make installdeps
       - name: Install wasm-pack
         uses: jetli/wasm-pack-action@v0.3.0
-      - name: Install cargo-make
-        run: cargo install cargo-make
-      - name: cargo make build
+      - name: cross make build
         run: |
-          cargo make build
+          cross make build
           mkdir release
           cp pkg/** release/
           tar -czvf browser-rln-wasm.tar.gz release/
@@ -111,7 +122,7 @@ jobs:
         uses: actions/download-artifact@v2
           
       - name: Delete tag
-        uses: dev-drprasad/delete-tag-and-release@v0.2.0
+        uses: dev-drprasad/delete-tag-and-release@v0.2.1
         with:
           delete_release: true
           tag_name: nightly
@@ -120,14 +131,13 @@ jobs:
 
       - name: Create prerelease
         run: |
-          start_tag=$(gh release list -L 2 --exclude-drafts | grep -v nightly | cut -d$'\t' -f3)
+          start_tag=$(gh release list -L 2 --exclude-drafts | grep -v nightly | cut -d$'\t' -f3 | sed -n '1p')
           gh release create nightly --prerelease --target master \
             --title 'Nightly build ("master" branch)' \
             --generate-notes \
+            --draft=false \
             --notes-start-tag $start_tag \
-            linux-archive/linux-rln.tar.gz \
-            macos-archive/macos-rln.tar.gz \
-            browser-rln-wasm-archive/browser-rln-wasm.tar.gz
+            *-archive/*.tar.gz \
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
@@ -136,6 +146,4 @@ jobs:
         with:
           failOnError: false
           name: |
-            linux-archive
-            macos-archive
-            browser-rln-wasm-archive
+            *-archive

.gitignore

@@ -8,10 +8,7 @@ rln/pmtree_db
 # will have compiled files and executables
 debug/
 target/
-
-# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
-# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
-Cargo.lock
+wabt/
 
 # These are backup files generated by rustfmt
 **/*.rs.bk

CHANGELOG.md

@@ -1,18 +1,15 @@
-## Upcoming release
+## 2023-02-28 v0.2
 
-Release highlights:
+This release contains:
+
+- Improved code quality
 - Allows consumers of zerokit RLN to set leaves to the Merkle Tree from an arbitrary index. Useful for batching updates to the Merkle Tree.
+- Improved performance for proof generation and verification
+- rln_wasm which allows for the consumption of RLN through a WebAssembly interface
+- Refactored to generate Semaphore-compatible credentials
+- Dual License under Apache 2.0 and MIT
+- RLN compiles as a static library, which can be consumed through a C FFI
 
-The full list of changes is below.
-
-### Features
-- Creation of `set_leaves_from`, which allows consumers to add leaves to a tree from a given starting index. `init_tree_with_leaves` internally uses `set_leaves_from`, with index 0.
-
-### Changes
-- Renaming of `set_leaves` to `init_tree_with_leaves`, which is a more accurate representation of the function's utility.
-
-### Fixes
-- None
 
 ## 2022-09-19 v0.1
 

Cargo.toml

@@ -7,3 +7,16 @@ members = [
   "rln-wasm",
   "utils",
 ]
+
+# Compilation profile for any non-workspace member.
+# Dependencies are optimized, even in a dev build. This improves dev performance
+# while having neglible impact on incremental build times.
+[profile.dev.package."*"]
+opt-level = 3
+
+[profile.release.package."rln-wasm"]
+# Tell `rustc` to optimize for small code size.
+opt-level = "s"
+
+[profile.release.package."semaphore"]
+codegen-units = 1

Cross.toml

@@ -0,0 +1,32 @@
+[target.x86_64-pc-windows-gnu]
+image = "ghcr.io/cross-rs/x86_64-pc-windows-gnu:latest"
+
+[target.aarch64-unknown-linux-gnu]
+image = "ghcr.io/cross-rs/aarch64-unknown-linux-gnu:latest"
+
+[target.x86_64-unknown-linux-gnu]
+image = "ghcr.io/cross-rs/x86_64-unknown-linux-gnu:latest"
+
+[target.arm-unknown-linux-gnueabi]
+image = "ghcr.io/cross-rs/arm-unknown-linux-gnueabi:latest"
+
+[target.i686-pc-windows-gnu]
+image = "ghcr.io/cross-rs/i686-pc-windows-gnu:latest"
+
+[target.i686-unknown-linux-gnu]
+image = "ghcr.io/cross-rs/i686-unknown-linux-gnu:latest"
+
+[target.arm-unknown-linux-gnueabihf]
+image = "ghcr.io/cross-rs/arm-unknown-linux-gnueabihf:latest"
+
+[target.mips-unknown-linux-gnu]
+image = "ghcr.io/cross-rs/mips-unknown-linux-gnu:latest"
+
+[target.mips64-unknown-linux-gnuabi64]
+image = "ghcr.io/cross-rs/mips64-unknown-linux-gnuabi64:latest"
+
+[target.mips64el-unknown-linux-gnuabi64]
+image = "ghcr.io/cross-rs/mips64el-unknown-linux-gnuabi64:latest"
+
+[target.mipsel-unknown-linux-gnu]
+image = "ghcr.io/cross-rs/mipsel-unknown-linux-gnu:latest"

LICENSE-APACHE

@@ -0,0 +1,203 @@
+Copyright (c) 2022 Vac Research
+
+                              Apache License
+                        Version 2.0, January 2004
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LICENSE-MIT

@@ -0,0 +1,25 @@
+Copyright (c) 2022 Vac Research
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE O THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

Makefile

@@ -1,13 +1,30 @@
-.PHONY: all test clean
+.PHONY: all installdeps build test clean
 
-all: .pre-build
-	@cargo make build
+all: .pre-build build
 
-.pre-build:
-ifndef $(cargo make --help)
-	@cargo install --force cargo-make
+.fetch-submodules:
+	@git submodule update --init --recursive
+
+.pre-build: .fetch-submodules
+	@cargo install cargo-make
+ifdef CI
+	@cargo install cross --git https://github.com/cross-rs/cross --branch main
 endif
 
+installdeps: .pre-build
+ifeq ($(shell uname),Darwin)
+	@brew update
+	@brew install cmake ninja
+else ifeq ($(shell uname),Linux)
+	@sudo apt-get update
+	@sudo apt-get install -y cmake ninja-build
+endif
+	@git clone --recursive https://github.com/WebAssembly/wabt.git
+	@cd wabt && mkdir build && cd build && cmake .. -GNinja && ninja && sudo ninja install
+
+build: .pre-build
+	@cargo make build
+
 test: .pre-build
 	@cargo make test
 

README.md

@@ -17,3 +17,19 @@ in Rust.
 - [RLN library](https://github.com/kilic/rln) written in Rust based on Bellman.
 
 - [semaphore-rs](https://github.com/worldcoin/semaphore-rs) written in Rust based on ark-circom.
+
+## Build and Test
+
+To install missing dependencies, run the following commands from the root folder
+```bash
+make installdeps
+```
+To build and test all crates, run the following commands from the root folder
+```bash
+make build
+make test
+```
+
+## Release assets
+
+We use [`cross-rs`](https://github.com/cross-rs/cross) to cross-compile and generate release assets for rln. 

multiplier/Cargo.toml

@@ -2,6 +2,7 @@
 name = "multiplier"
 version = "0.1.0"
 edition = "2018"
+license = "MIT OR Apache-2.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -12,23 +13,19 @@ edition = "2018"
 # fnv = { version = "1.0.3", default-features = false }
 # num = { version = "0.4.0" }
 # num-traits = { version = "0.2.0", default-features = false }
-num-bigint = { version = "0.4", default-features = false, features = ["rand"] }
 
 # ZKP Generation
-ark-ec = { version = "0.3.0", default-features = false, features = ["parallel"] }
 # ark-ff = { version = "0.3.0", default-features = false, features = ["parallel", "asm"] }
 ark-std = { version = "0.3.0", default-features = false, features = ["parallel"] }
 ark-bn254 = { version = "0.3.0" }
 ark-groth16 = { git = "https://github.com/arkworks-rs/groth16", rev = "765817f", features = ["parallel"] }
 # ark-poly = { version = "^0.3.0", default-features = false, features = ["parallel"] }
-ark-relations = { version = "0.3.0", default-features = false }
 ark-serialize = { version = "0.3.0", default-features = false }
 
-ark-circom = { git = "https://github.com/gakonst/ark-circom", features = ["circom-2"] }
+ark-circom = { git = "https://github.com/gakonst/ark-circom", features = ["circom-2"], rev = "35ce5a9" }
 
 # error handling
-# thiserror = "1.0.26"
-color-eyre = "0.5"
+color-eyre = "0.6.1"
 
 # decoding of data
 # hex = "0.4.3"

multiplier/README.md

@@ -3,7 +3,15 @@
 Example wrapper around a basic Circom circuit to test Circom 2 integration
 through ark-circom and FFI.
 
-# FFI
+## Build and Test
+
+To build and test, run the following commands within the module folder
+```bash
+cargo make build
+cargo make test
+```
+
+## FFI
 
 To generate C or Nim bindings from Rust FFI, use `cbindgen` or `nbindgen`:
 

multiplier/src/ffi.rs

@@ -31,12 +31,12 @@ impl<'a> From<&Buffer> for &'a [u8] {
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[no_mangle]
 pub extern "C" fn new_circuit(ctx: *mut *mut Multiplier) -> bool {
-    println!("multiplier ffi: new");
-    let mul = Multiplier::new();
-
-    unsafe { *ctx = Box::into_raw(Box::new(mul)) };
-
-    true
+    if let Ok(mul) = Multiplier::new() {
+        unsafe { *ctx = Box::into_raw(Box::new(mul)) };
+        true
+    } else {
+        false
+    }
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]

multiplier/src/main.rs

@@ -1,6 +1,6 @@
 use ark_circom::{CircomBuilder, CircomConfig};
 use ark_std::rand::thread_rng;
-use color_eyre::Result;
+use color_eyre::{Report, Result};
 
 use ark_bn254::Bn254;
 use ark_groth16::{
@@ -25,17 +25,18 @@ fn groth16_proof_example() -> Result<()> {
 
     let circom = builder.build()?;
 
-    let inputs = circom.get_public_inputs().unwrap();
+    let inputs = circom
+        .get_public_inputs()
+        .ok_or(Report::msg("no public inputs"))?;
 
     let proof = prove(circom, &params, &mut rng)?;
 
     let pvk = prepare_verifying_key(&params.vk);
 
-    let verified = verify_proof(&pvk, &proof, &inputs)?;
-
-    assert!(verified);
-
-    Ok(())
+    match verify_proof(&pvk, &proof, &inputs) {
+        Ok(_) => Ok(()),
+        Err(_) => Err(Report::msg("not verified")),
+    }
 }
 
 fn main() {

multiplier/src/public.rs

@@ -7,9 +7,8 @@ use ark_groth16::{
     Proof, ProvingKey,
 };
 use ark_serialize::{CanonicalDeserialize, CanonicalSerialize};
-// , SerializationError};
-
-use std::io::{self, Read, Write};
+use color_eyre::{Report, Result};
+use std::io::{Read, Write};
 
 pub struct Multiplier {
     circom: CircomCircuit<Bn254>,
@@ -18,12 +17,11 @@ pub struct Multiplier {
 
 impl Multiplier {
     // TODO Break this apart here
-    pub fn new() -> Multiplier {
+    pub fn new() -> Result<Multiplier> {
         let cfg = CircomConfig::<Bn254>::new(
             "./resources/circom2_multiplier2.wasm",
             "./resources/circom2_multiplier2.r1cs",
-        )
-        .unwrap();
+        )?;
 
         let mut builder = CircomBuilder::new(cfg);
         builder.push_input("a", 3);
@@ -34,40 +32,41 @@ impl Multiplier {
 
         let mut rng = thread_rng();
 
-        let params = generate_random_parameters::<Bn254, _, _>(circom, &mut rng).unwrap();
+        let params = generate_random_parameters::<Bn254, _, _>(circom, &mut rng)?;
 
-        let circom = builder.build().unwrap();
+        let circom = builder.build()?;
 
-        //let inputs = circom.get_public_inputs().unwrap();
-
-        Multiplier { circom, params }
+        Ok(Multiplier { circom, params })
     }
 
     // TODO Input Read
-    pub fn prove<W: Write>(&self, result_data: W) -> io::Result<()> {
+    pub fn prove<W: Write>(&self, result_data: W) -> Result<()> {
         let mut rng = thread_rng();
 
         // XXX: There's probably a better way to do this
         let circom = self.circom.clone();
         let params = self.params.clone();
 
-        let proof = prove(circom, &params, &mut rng).unwrap();
+        let proof = prove(circom, &params, &mut rng)?;
 
         // XXX: Unclear if this is different from other serialization(s)
-        let _ = proof.serialize(result_data).unwrap();
+        proof.serialize(result_data)?;
 
         Ok(())
     }
 
-    pub fn verify<R: Read>(&self, input_data: R) -> io::Result<bool> {
-        let proof = Proof::deserialize(input_data).unwrap();
+    pub fn verify<R: Read>(&self, input_data: R) -> Result<bool> {
+        let proof = Proof::deserialize(input_data)?;
 
         let pvk = prepare_verifying_key(&self.params.vk);
 
         // XXX Part of input data?
-        let inputs = self.circom.get_public_inputs().unwrap();
+        let inputs = self
+            .circom
+            .get_public_inputs()
+            .ok_or(Report::msg("no public inputs"))?;
 
-        let verified = verify_proof(&pvk, &proof, &inputs).unwrap();
+        let verified = verify_proof(&pvk, &proof, &inputs)?;
 
         Ok(verified)
     }
@@ -75,6 +74,6 @@ impl Multiplier {
 
 impl Default for Multiplier {
     fn default() -> Self {
-        Self::new()
+        Self::new().unwrap()
     }
 }

multiplier/tests/public.rs

@@ -4,8 +4,7 @@ mod tests {
 
     #[test]
     fn multiplier_proof() {
-        let mul = Multiplier::new();
-        //let inputs = mul.circom.get_public_inputs().unwrap();
+        let mul = Multiplier::new().unwrap();
 
         let mut output_data: Vec<u8> = Vec::new();
         let _ = mul.prove(&mut output_data);

private-settlement/Cargo.toml

@@ -2,6 +2,7 @@
 name = "private-settlement"
 version = "0.1.0"
 edition = "2021"
+license = "MIT OR Apache-2.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

private-settlement/README.md

@@ -2,3 +2,10 @@
 
 This module is to provide APIs to manage, compute and verify [Private Settlement](https://rfc.vac.dev/spec/44/) zkSNARK proofs and primitives.
 
+## Build and Test
+
+To build and test, run the following commands within the module folder
+```bash
+cargo make build
+cargo make test
+```

rln-wasm/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rln-wasm"
-version = "0.0.7"
+version = "0.0.8"
 edition = "2021"
 license = "MIT or Apache2"
 
@@ -31,6 +31,3 @@ console_error_panic_hook = { version = "0.1.7", optional = true }
 wasm-bindgen-test = "0.3.13"
 wasm-bindgen-futures = "0.4.33"
 
-[profile.release]
-# Tell `rustc` to optimize for small code size.
-opt-level = "s"

rln-wasm/Makefile.toml

@@ -9,9 +9,14 @@ script = "sed -i.bak 's/rln-wasm/zerokit-rln-wasm/g' pkg/package.json && rm pkg/
 clear = true
 dependencies = [
     "pack-build",
-    "pack-rename"
+    "pack-rename",
+    "post-build"
 ]
 
+[tasks.post-build]
+command = "wasm-strip"
+args = ["./pkg/rln_wasm_bg.wasm"]
+
 [tasks.test]
 command = "wasm-pack"
 args = ["test", "--release", "--node"]

rln-wasm/README.md

@@ -10,11 +10,22 @@ curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh
 ```
 cargo install cargo-make
 ```
+
+OR
+
+```
+make installdeps
+```
 3. Compile zerokit for `wasm32-unknown-unknown`:
 ```
 cd rln-wasm
 cargo make build
 ```
+4. Compile a slimmer version of zerokit for `wasm32-unknown-unknown`:
+```
+cd rln-wasm
+cargo make post-build
+```
 
 ## Running tests
 ```

rln-wasm/src/lib.rs

@@ -3,9 +3,11 @@
 extern crate wasm_bindgen;
 extern crate web_sys;
 
+use std::vec::Vec;
+
 use js_sys::{BigInt as JsBigInt, Object, Uint8Array};
 use num_bigint::BigInt;
-use rln::public::RLN;
+use rln::public::{hash, poseidon_hash, RLN};
 use wasm_bindgen::prelude::*;
 
 #[wasm_bindgen]
@@ -20,34 +22,196 @@ pub struct RLNWrapper {
     instance: RLN<'static>,
 }
 
+// Macro to call methods with arbitrary amount of arguments,
+// which have the last argument is output buffer pointer
+// First argument to the macro is context,
+// second is the actual method on `RLN`
+// third is the aforementioned output buffer argument
+// rest are all other arguments to the method
+macro_rules! call_with_output_and_error_msg {
+    // this variant is needed for the case when
+    // there are zero other arguments
+    ($instance:expr, $method:ident, $error_msg:expr) => {
+        {
+            let mut output_data: Vec<u8> = Vec::new();
+            let new_instance = $instance.process();
+            if let Err(err) = new_instance.instance.$method(&mut output_data) {
+                std::mem::forget(output_data);
+                Err(format!("Msg: {:#?}, Error: {:#?}", $error_msg, err))
+            } else {
+                let result = Uint8Array::from(&output_data[..]);
+                std::mem::forget(output_data);
+                Ok(result)
+            }
+        }
+    };
+    ($instance:expr, $method:ident, $error_msg:expr, $( $arg:expr ),* ) => {
+        {
+            let mut output_data: Vec<u8> = Vec::new();
+            let new_instance = $instance.process();
+            if let Err(err) = new_instance.instance.$method($($arg.process()),*, &mut output_data) {
+                std::mem::forget(output_data);
+                Err(format!("Msg: {:#?}, Error: {:#?}", $error_msg, err))
+            } else {
+                let result = Uint8Array::from(&output_data[..]);
+                std::mem::forget(output_data);
+                Ok(result)
+            }
+        }
+    };
+}
+
+// Macro to call_with_error_msg methods with arbitrary amount of arguments,
+// First argument to the macro is context,
+// second is the actual method on `RLNWrapper`
+// rest are all other arguments to the method
+macro_rules! call_with_error_msg {
+    ($instance:expr, $method:ident, $error_msg:expr $(, $arg:expr)*) => {
+        {
+            let new_instance: &mut RLNWrapper = $instance.process();
+            if let Err(err) = new_instance.instance.$method($($arg.process()),*) {
+                Err(format!("Msg: {:#?}, Error: {:#?}", $error_msg, err))
+            } else {
+                Ok(())
+            }
+
+        }
+    }
+}
+
+macro_rules! call {
+    ($instance:expr, $method:ident $(, $arg:expr)*) => {
+        {
+            let new_instance: &mut RLNWrapper = $instance.process();
+            new_instance.instance.$method($($arg.process()),*)
+        }
+    }
+}
+
+macro_rules! call_bool_method_with_error_msg {
+    ($instance:expr, $method:ident, $error_msg:expr $(, $arg:expr)*) => {
+        {
+            let new_instance: &RLNWrapper = $instance.process();
+            new_instance.instance.$method($($arg.process()),*).map_err(|err| format!("Msg: {:#?}, Error: {:#?}", $error_msg, err))
+        }
+    }
+}
+
+// Macro to execute a function with arbitrary amount of arguments,
+// First argument is the function to execute
+// Rest are all other arguments to the method
+macro_rules! fn_call_with_output_and_error_msg {
+    // this variant is needed for the case when
+    // there are zero other arguments
+    ($func:ident, $error_msg:expr) => {
+        {
+            let mut output_data: Vec<u8> = Vec::new();
+            if let Err(err) = $func(&mut output_data) {
+                std::mem::forget(output_data);
+                Err(format!("Msg: {:#?}, Error: {:#?}", $error_msg, err))
+            } else {
+                let result = Uint8Array::from(&output_data[..]);
+                std::mem::forget(output_data);
+                Ok(result)
+            }
+        }
+    };
+    ($func:ident, $error_msg:expr, $( $arg:expr ),* ) => {
+        {
+            let mut output_data: Vec<u8> = Vec::new();
+            if let Err(err) = $func($($arg.process()),*, &mut output_data) {
+                std::mem::forget(output_data);
+                Err(format!("Msg: {:#?}, Error: {:#?}", $error_msg, err))
+            } else {
+                let result = Uint8Array::from(&output_data[..]);
+                std::mem::forget(output_data);
+                Ok(result)
+            }
+        }
+    };
+}
+
+trait ProcessArg {
+    type ReturnType;
+    fn process(self) -> Self::ReturnType;
+}
+
+impl ProcessArg for usize {
+    type ReturnType = usize;
+    fn process(self) -> Self::ReturnType {
+        self
+    }
+}
+
+impl<T> ProcessArg for Vec<T> {
+    type ReturnType = Vec<T>;
+    fn process(self) -> Self::ReturnType {
+        self
+    }
+}
+
+impl<'a> ProcessArg for *const RLN<'a> {
+    type ReturnType = &'a RLN<'a>;
+    fn process(self) -> Self::ReturnType {
+        unsafe { &*self }
+    }
+}
+
+impl ProcessArg for *const RLNWrapper {
+    type ReturnType = &'static RLNWrapper;
+    fn process(self) -> Self::ReturnType {
+        unsafe { &*self }
+    }
+}
+
+impl ProcessArg for *mut RLNWrapper {
+    type ReturnType = &'static mut RLNWrapper;
+    fn process(self) -> Self::ReturnType {
+        unsafe { &mut *self }
+    }
+}
+
+impl<'a> ProcessArg for &'a [u8] {
+    type ReturnType = &'a [u8];
+
+    fn process(self) -> Self::ReturnType {
+        self
+    }
+}
+
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = newRLN)]
-pub fn wasm_new(tree_height: usize, zkey: Uint8Array, vk: Uint8Array) -> *mut RLNWrapper {
-    let instance = RLN::new_with_params(tree_height, zkey.to_vec(), vk.to_vec());
+pub fn wasm_new(
+    tree_height: usize,
+    zkey: Uint8Array,
+    vk: Uint8Array,
+) -> Result<*mut RLNWrapper, String> {
+    let instance = RLN::new_with_params(tree_height, zkey.to_vec(), vk.to_vec())
+        .map_err(|err| format!("{:#?}", err))?;
     let wrapper = RLNWrapper { instance };
-    Box::into_raw(Box::new(wrapper))
+    Ok(Box::into_raw(Box::new(wrapper)))
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = getSerializedRLNWitness)]
-pub fn wasm_get_serialized_rln_witness(ctx: *mut RLNWrapper, input: Uint8Array) -> Uint8Array {
-    let wrapper = unsafe { &mut *ctx };
-    let rln_witness = wrapper
-        .instance
-        .get_serialized_rln_witness(&input.to_vec()[..]);
-
-    Uint8Array::from(&rln_witness[..])
+pub fn wasm_get_serialized_rln_witness(
+    ctx: *mut RLNWrapper,
+    input: Uint8Array,
+) -> Result<Uint8Array, String> {
+    let rln_witness = call!(ctx, get_serialized_rln_witness, &input.to_vec()[..])
+        .map_err(|err| format!("{:#?}", err))?;
+    Ok(Uint8Array::from(&rln_witness[..]))
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = insertMember)]
 pub fn wasm_set_next_leaf(ctx: *mut RLNWrapper, input: Uint8Array) -> Result<(), String> {
-    let wrapper = unsafe { &mut *ctx };
-    if wrapper.instance.set_next_leaf(&input.to_vec()[..]).is_ok() {
-        Ok(())
-    } else {
-        Err("could not insert member into merkle tree".into())
-    }
+    call_with_error_msg!(
+        ctx,
+        set_next_leaf,
+        "could not insert member into merkle tree".to_string(),
+        &input.to_vec()[..]
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
@@ -57,45 +221,42 @@ pub fn wasm_set_leaves_from(
     index: usize,
     input: Uint8Array,
 ) -> Result<(), String> {
-    let wrapper = unsafe { &mut *ctx };
-    if wrapper
-        .instance
-        .set_leaves_from(index as usize, &input.to_vec()[..])
-        .is_ok()
-    {
-        Ok(())
-    } else {
-        Err("could not set multiple leaves".into())
-    }
+    call_with_error_msg!(
+        ctx,
+        set_leaves_from,
+        "could not set multiple leaves".to_string(),
+        index,
+        &*input.to_vec()
+    )
+}
+
+#[allow(clippy::not_unsafe_ptr_arg_deref)]
+#[wasm_bindgen(js_name = deleteLeaf)]
+pub fn wasm_delete_leaf(ctx: *mut RLNWrapper, index: usize) -> Result<(), String> {
+    call_with_error_msg!(ctx, delete_leaf, "could not delete leaf".to_string(), index)
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = initTreeWithLeaves)]
 pub fn wasm_init_tree_with_leaves(ctx: *mut RLNWrapper, input: Uint8Array) -> Result<(), String> {
-    let wrapper = unsafe { &mut *ctx };
-    if wrapper
-        .instance
-        .init_tree_with_leaves(&input.to_vec()[..])
-        .is_ok()
-    {
-        Ok(())
-    } else {
-        Err("could not init merkle tree".into())
-    }
+    call_with_error_msg!(
+        ctx,
+        init_tree_with_leaves,
+        "could not init merkle tree".to_string(),
+        &*input.to_vec()
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = RLNWitnessToJson)]
-pub fn rln_witness_to_json(ctx: *mut RLNWrapper, serialized_witness: Uint8Array) -> Object {
-    let wrapper = unsafe { &mut *ctx };
-    let inputs = wrapper
-        .instance
-        .get_rln_witness_json(&serialized_witness.to_vec()[..])
-        .unwrap();
-
-    let js_value = serde_wasm_bindgen::to_value(&inputs).unwrap();
-    let obj = Object::from_entries(&js_value);
-    obj.unwrap()
+pub fn rln_witness_to_json(
+    ctx: *mut RLNWrapper,
+    serialized_witness: Uint8Array,
+) -> Result<Object, String> {
+    let inputs = call!(ctx, get_rln_witness_json, &serialized_witness.to_vec()[..])
+        .map_err(|err| err.to_string())?;
+    let js_value = serde_wasm_bindgen::to_value(&inputs).map_err(|err| err.to_string())?;
+    Object::from_entries(&js_value).map_err(|err| format!("{:#?}", err))
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
@@ -105,83 +266,49 @@ pub fn generate_rln_proof_with_witness(
     calculated_witness: Vec<JsBigInt>,
     serialized_witness: Uint8Array,
 ) -> Result<Uint8Array, String> {
-    let wrapper = unsafe { &mut *ctx };
+    let mut witness_vec: Vec<BigInt> = vec![];
 
-    let witness_vec: Vec<BigInt> = calculated_witness
-        .iter()
-        .map(|v| {
+    for v in calculated_witness {
+        witness_vec.push(
             v.to_string(10)
-                .unwrap()
+                .map_err(|err| format!("{:#?}", err))?
                 .as_string()
-                .unwrap()
+                .ok_or("not a string error")?
                 .parse::<BigInt>()
-                .unwrap()
-        })
-        .collect();
-
-    let mut output_data: Vec<u8> = Vec::new();
-
-    if wrapper
-        .instance
-        .generate_rln_proof_with_witness(witness_vec, serialized_witness.to_vec(), &mut output_data)
-        .is_ok()
-    {
-        let result = Uint8Array::from(&output_data[..]);
-        std::mem::forget(output_data);
-        Ok(result)
-    } else {
-        std::mem::forget(output_data);
-        Err("could not generate proof".into())
+                .map_err(|err| format!("{:#?}", err))?,
+        );
     }
+
+    call_with_output_and_error_msg!(
+        ctx,
+        generate_rln_proof_with_witness,
+        "could not generate proof",
+        witness_vec,
+        serialized_witness.to_vec()
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = generateMembershipKey)]
 pub fn wasm_key_gen(ctx: *const RLNWrapper) -> Result<Uint8Array, String> {
-    let wrapper = unsafe { &*ctx };
-    let mut output_data: Vec<u8> = Vec::new();
-    if wrapper.instance.key_gen(&mut output_data).is_ok() {
-        let result = Uint8Array::from(&output_data[..]);
-        std::mem::forget(output_data);
-        Ok(result)
-    } else {
-        std::mem::forget(output_data);
-        Err("could not generate membership keys".into())
-    }
+    call_with_output_and_error_msg!(ctx, key_gen, "could not generate membership keys")
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = generateExtendedMembershipKey)]
 pub fn wasm_extended_key_gen(ctx: *const RLNWrapper) -> Result<Uint8Array, String> {
-    let wrapper = unsafe { &*ctx };
-    let mut output_data: Vec<u8> = Vec::new();
-    if wrapper.instance.extended_key_gen(&mut output_data).is_ok() {
-        let result = Uint8Array::from(&output_data[..]);
-        std::mem::forget(output_data);
-        Ok(result)
-    } else {
-        std::mem::forget(output_data);
-        Err("could not generate membership keys".into())
-    }
+    call_with_output_and_error_msg!(ctx, extended_key_gen, "could not generate membership keys")
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = generateSeededMembershipKey)]
 pub fn wasm_seeded_key_gen(ctx: *const RLNWrapper, seed: Uint8Array) -> Result<Uint8Array, String> {
-    let wrapper = unsafe { &*ctx };
-    let mut output_data: Vec<u8> = Vec::new();
-    if wrapper
-        .instance
-        .seeded_key_gen(&seed.to_vec()[..], &mut output_data)
-        .is_ok()
-    {
-        let result = Uint8Array::from(&output_data[..]);
-        std::mem::forget(output_data);
-        Ok(result)
-    } else {
-        std::mem::forget(output_data);
-        Err("could not generate membership key".into())
-    }
+    call_with_output_and_error_msg!(
+        ctx,
+        seeded_key_gen,
+        "could not generate membership key",
+        &seed.to_vec()[..]
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
@@ -190,20 +317,12 @@ pub fn wasm_seeded_extended_key_gen(
     ctx: *const RLNWrapper,
     seed: Uint8Array,
 ) -> Result<Uint8Array, String> {
-    let wrapper = unsafe { &*ctx };
-    let mut output_data: Vec<u8> = Vec::new();
-    if wrapper
-        .instance
-        .seeded_extended_key_gen(&seed.to_vec()[..], &mut output_data)
-        .is_ok()
-    {
-        let result = Uint8Array::from(&output_data[..]);
-        std::mem::forget(output_data);
-        Ok(result)
-    } else {
-        std::mem::forget(output_data);
-        Err("could not generate membership key".into())
-    }
+    call_with_output_and_error_msg!(
+        ctx,
+        seeded_extended_key_gen,
+        "could not generate membership key",
+        &seed.to_vec()[..]
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
@@ -213,38 +332,24 @@ pub fn wasm_recover_id_secret(
     input_proof_data_1: Uint8Array,
     input_proof_data_2: Uint8Array,
 ) -> Result<Uint8Array, String> {
-    let wrapper = unsafe { &*ctx };
-    let mut output_data: Vec<u8> = Vec::new();
-    if wrapper
-        .instance
-        .recover_id_secret(
-            &input_proof_data_1.to_vec()[..],
-            &input_proof_data_2.to_vec()[..],
-            &mut output_data,
-        )
-        .is_ok()
-    {
-        let result = Uint8Array::from(&output_data[..]);
-        std::mem::forget(output_data);
-        Ok(result)
-    } else {
-        std::mem::forget(output_data);
-        Err("could not recover id secret".into())
-    }
+    call_with_output_and_error_msg!(
+        ctx,
+        recover_id_secret,
+        "could not recover id secret",
+        &input_proof_data_1.to_vec()[..],
+        &input_proof_data_2.to_vec()[..]
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = verifyRLNProof)]
 pub fn wasm_verify_rln_proof(ctx: *const RLNWrapper, proof: Uint8Array) -> Result<bool, String> {
-    let wrapper = unsafe { &*ctx };
-    if match wrapper.instance.verify_rln_proof(&proof.to_vec()[..]) {
-        Ok(verified) => verified,
-        Err(_) => return Err("error while verifying rln proof".into()),
-    } {
-        return Ok(true);
-    }
-
-    Ok(false)
+    call_bool_method_with_error_msg!(
+        ctx,
+        verify_rln_proof,
+        "error while verifying rln proof".to_string(),
+        &proof.to_vec()[..]
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
@@ -254,31 +359,31 @@ pub fn wasm_verify_with_roots(
     proof: Uint8Array,
     roots: Uint8Array,
 ) -> Result<bool, String> {
-    let wrapper = unsafe { &*ctx };
-    if match wrapper
-        .instance
-        .verify_with_roots(&proof.to_vec()[..], &roots.to_vec()[..])
-    {
-        Ok(verified) => verified,
-        Err(_) => return Err("error while verifying proof with roots".into()),
-    } {
-        return Ok(true);
-    }
-
-    Ok(false)
+    call_bool_method_with_error_msg!(
+        ctx,
+        verify_with_roots,
+        "error while verifying proof with roots".to_string(),
+        &proof.to_vec()[..],
+        &roots.to_vec()[..]
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = getRoot)]
 pub fn wasm_get_root(ctx: *const RLNWrapper) -> Result<Uint8Array, String> {
-    let wrapper = unsafe { &*ctx };
-    let mut output_data: Vec<u8> = Vec::new();
-    if wrapper.instance.get_root(&mut output_data).is_ok() {
-        let result = Uint8Array::from(&output_data[..]);
-        std::mem::forget(output_data);
-        Ok(result)
-    } else {
-        std::mem::forget(output_data);
-        Err("could not obtain root".into())
-    }
+    call_with_output_and_error_msg!(ctx, get_root, "could not obtain root")
+}
+
+#[wasm_bindgen(js_name = hash)]
+pub fn wasm_hash(input: Uint8Array) -> Result<Uint8Array, String> {
+    fn_call_with_output_and_error_msg!(hash, "could not generate hash", &input.to_vec()[..])
+}
+
+#[wasm_bindgen(js_name = poseidonHash)]
+pub fn wasm_poseidon_hash(input: Uint8Array) -> Result<Uint8Array, String> {
+    fn_call_with_output_and_error_msg!(
+        poseidon_hash,
+        "could not generate poseidon hash",
+        &input.to_vec()[..]
+    )
 }

rln-wasm/tests/rln-wasm.rs

@@ -4,6 +4,7 @@
 mod tests {
     use js_sys::{BigInt as JsBigInt, Object, Uint8Array};
     use rln::circuit::TEST_TREE_HEIGHT;
+    use rln::utils::normalize_usize;
     use rln_wasm::*;
     use wasm_bindgen::prelude::*;
     use wasm_bindgen::JsValue;
@@ -41,20 +42,19 @@ mod tests {
 
         // Prepare the message
         let signal = "Hello World".as_bytes();
-        let signal_len: u64 = signal.len() as u64;
 
         // Setting up the epoch (With 0s for the test)
         let epoch = Uint8Array::new_with_length(32);
         epoch.fill(0, 0, 32);
 
-        let identity_index: u64 = 0;
+        let identity_index: usize = 0;
 
         // Serializing the message
         let mut serialized_vec: Vec<u8> = Vec::new();
         serialized_vec.append(&mut idkey.to_vec());
-        serialized_vec.append(&mut identity_index.to_le_bytes().to_vec());
+        serialized_vec.append(&mut normalize_usize(identity_index));
         serialized_vec.append(&mut epoch.to_vec());
-        serialized_vec.append(&mut signal_len.to_le_bytes().to_vec());
+        serialized_vec.append(&mut normalize_usize(signal.len()));
         serialized_vec.append(&mut signal.to_vec());
         let serialized_message = Uint8Array::from(&serialized_vec[..]);
 
@@ -88,7 +88,7 @@ mod tests {
 
         // Add signal_len | signal
         let mut proof_bytes = proof.to_vec();
-        proof_bytes.append(&mut signal_len.to_le_bytes().to_vec());
+        proof_bytes.append(&mut normalize_usize(signal.len()));
         proof_bytes.append(&mut signal.to_vec());
         let proof_with_signal = Uint8Array::from(&proof_bytes[..]);
 

rln/Cargo.toml

@@ -2,9 +2,10 @@
 name = "rln"
 version = "0.1.0"
 edition = "2021"
+license = "MIT OR Apache-2.0"
 
 [lib]
-crate-type = ["cdylib", "rlib", "staticlib"]
+crate-type = ["rlib", "staticlib"]
 
 # This flag disable cargo doctests, i.e. testing example code-snippets in documentation
 doctest = false
@@ -12,39 +13,40 @@ doctest = false
 
 [dependencies]
 # ZKP Generation
-ark-ec = { version = "0.3.0", default-features = false }
-ark-ff = { version = "0.3.0", default-features = false, features = [ "asm"] }
-ark-std = { version = "0.3.0", default-features = false }
-ark-bn254 = { version = "0.3.0" }
-ark-groth16 = { git = "https://github.com/arkworks-rs/groth16", rev = "765817f", default-features = false }
-ark-relations = { version = "0.3.0", default-features = false, features = [ "std" ] }
-ark-serialize = { version = "0.3.0", default-features = false }
-ark-circom = { git = "https://github.com/vacp2p/ark-circom", branch = "wasm", default-features = false, features = ["circom-2"] }
-#ark-circom = { git = "https://github.com/vacp2p/ark-circom", branch = "no-ethers-core", features = ["circom-2"] }
+ark-ec = { version = "=0.4.1", default-features = false }
+ark-ff = { version = "=0.4.1", default-features = false, features = [ "asm"] }
+ark-std = { version = "=0.4.0", default-features = false }
+ark-bn254 = { version = "=0.4.0" }
+ark-groth16 = { version = "=0.4.0", features = ["parallel"], default-features = false }
+ark-relations = { version = "=0.4.0", default-features = false, features = [ "std" ] }
+ark-serialize = { version = "=0.4.1", default-features = false }
+ark-circom = { git = "https://github.com/gakonst/ark-circom", default-features = false, features = ["circom-2"] }
 
 # WASM
 wasmer = { version = "2.3.0", default-features = false }
 
 # error handling
-color-eyre = "0.5.11"
-thiserror = "1.0.0"
+color-eyre = "=0.6.2"
+thiserror = "=1.0.38"
 
 # utilities
-cfg-if = "1.0"
-num-bigint = { version = "0.4.3", default-features = false, features = ["rand"] }
+cfg-if = "=1.0"
+num-bigint = { version = "=0.4.3", default-features = false, features = ["rand"] }
 num-traits = "0.2.11"
 once_cell = "1.14.0"
-rand = "0.8"
-rand_chacha = "0.3.1"
-tiny-keccak = { version = "2.0.2", features = ["keccak"] }
+rand = "=0.8.5"
+rand_chacha = "=0.3.1"
+tiny-keccak = { version = "=2.0.2", features = ["keccak"] }
 utils = { path = "../utils/", default-features = false }
+pmtree = { git = "https://github.com/Rate-Limiting-Nullifier/pmtree", rev = "f6d1a1fecad72cd39e6808e78085091d541dc882", optional = true}
 
 # serialization
 serde_json = "1.0.48"
 
+include_dir = "=0.7.3"
+
 [dev-dependencies]
-pmtree = { git = "https://github.com/Rate-Limiting-Nullifier/pmtree" }
-sled = "0.34.7"
+sled = "=0.34.7"
 
 [features]
 default = ["parallel", "wasmer/sys-default"]
@@ -53,4 +55,4 @@ wasm = ["wasmer/js", "wasmer/std"]
 fullmerkletree = ["default"]
 
 # Note: pmtree feature is still experimental
-pmtree = ["default"]
+pmtree-ft = ["default", "pmtree"]

rln/README.md

@@ -3,15 +3,21 @@
 This module provides APIs to manage, compute and verify [RLN](https://rfc.vac.dev/spec/32/) zkSNARK proofs and RLN primitives.
 
 ## Pre-requisites
-### Install
+### Install dependencies and clone repo
 
 ```sh
+make installdeps
 git clone https://github.com/vacp2p/zerokit.git
 cd zerokit/rln
 ```
-Implemented tests can be executed by running within the module folder
 
-`cargo test --release`
+### Build and Test
+
+To build and test, run the following commands within the module folder
+```bash
+cargo make build
+cargo make test
+```
 
 ### Compile ZK circuits
 

rln/src/circuit.rs

@@ -8,11 +8,10 @@ use ark_circom::read_zkey;
 use ark_groth16::{ProvingKey, VerifyingKey};
 use ark_relations::r1cs::ConstraintMatrices;
 use cfg_if::cfg_if;
+use color_eyre::{Report, Result};
 use num_bigint::BigUint;
 use serde_json::Value;
-use std::fs::File;
-use std::io::{Cursor, Error, ErrorKind, Result};
-use std::path::Path;
+use std::io::Cursor;
 use std::str::FromStr;
 
 cfg_if! {
@@ -21,11 +20,13 @@ cfg_if! {
         use once_cell::sync::OnceCell;
         use std::sync::Mutex;
         use wasmer::{Module, Store};
+        use include_dir::{include_dir, Dir};
+        use std::path::Path;
     }
 }
 
 const ZKEY_FILENAME: &str = "rln_final.zkey";
-const VK_FILENAME: &str = "verifying_key.json";
+const VK_FILENAME: &str = "verification_key.json";
 const WASM_FILENAME: &str = "rln.wasm";
 
 // These parameters are used for tests
@@ -33,11 +34,11 @@ const WASM_FILENAME: &str = "rln.wasm";
 // Changing these parameters to other values than these defaults will cause zkSNARK proof verification to fail
 pub const TEST_PARAMETERS_INDEX: usize = 2;
 pub const TEST_TREE_HEIGHT: usize = [15, 19, 20][TEST_PARAMETERS_INDEX];
-pub const TEST_RESOURCES_FOLDER: &str = [
-    "./resources/tree_height_15/",
-    "./resources/tree_height_19/",
-    "./resources/tree_height_20/",
-][TEST_PARAMETERS_INDEX];
+pub const TEST_RESOURCES_FOLDER: &str =
+    ["tree_height_15", "tree_height_19", "tree_height_20"][TEST_PARAMETERS_INDEX];
+
+#[cfg(not(target_arch = "wasm32"))]
+static RESOURCES_DIR: Dir<'_> = include_dir!("$CARGO_MANIFEST_DIR/resources");
 
 // The following types define the pairing friendly elliptic curve, the underlying finite fields and groups default to this module
 // Note that proofs are serialized assuming Fr to be 4x8 = 32 bytes in size. Hence, changing to a curve with different encoding will make proof verification to fail
@@ -57,21 +58,22 @@ pub fn zkey_from_raw(zkey_data: &Vec<u8>) -> Result<(ProvingKey<Curve>, Constrai
         let proving_key_and_matrices = read_zkey(&mut c)?;
         Ok(proving_key_and_matrices)
     } else {
-        Err(Error::new(ErrorKind::NotFound, "No proving key found!"))
+        Err(Report::msg("No proving key found!"))
     }
 }
 
 // Loads the proving key
+#[cfg(not(target_arch = "wasm32"))]
 pub fn zkey_from_folder(
     resources_folder: &str,
 ) -> Result<(ProvingKey<Curve>, ConstraintMatrices<Fr>)> {
-    let zkey_path = format!("{resources_folder}{ZKEY_FILENAME}");
-    if Path::new(&zkey_path).exists() {
-        let mut file = File::open(&zkey_path)?;
-        let proving_key_and_matrices = read_zkey(&mut file)?;
+    let zkey = RESOURCES_DIR.get_file(Path::new(resources_folder).join(ZKEY_FILENAME));
+    if let Some(zkey) = zkey {
+        let mut c = Cursor::new(zkey.contents());
+        let proving_key_and_matrices = read_zkey(&mut c)?;
         Ok(proving_key_and_matrices)
     } else {
-        Err(Error::new(ErrorKind::NotFound, "No proving key found!"))
+        Err(Report::msg("No proving key found!"))
     }
 }
 
@@ -80,39 +82,35 @@ pub fn vk_from_raw(vk_data: &Vec<u8>, zkey_data: &Vec<u8>) -> Result<VerifyingKe
     let verifying_key: VerifyingKey<Curve>;
 
     if !vk_data.is_empty() {
-        verifying_key = vk_from_vector(vk_data);
+        verifying_key = vk_from_vector(vk_data)?;
         Ok(verifying_key)
     } else if !zkey_data.is_empty() {
         let (proving_key, _matrices) = zkey_from_raw(zkey_data)?;
         verifying_key = proving_key.vk;
         Ok(verifying_key)
     } else {
-        Err(Error::new(
-            ErrorKind::NotFound,
-            "No proving/verification key found!",
-        ))
+        Err(Report::msg("No proving/verification key found!"))
     }
 }
 
 // Loads the verification key
+#[cfg(not(target_arch = "wasm32"))]
 pub fn vk_from_folder(resources_folder: &str) -> Result<VerifyingKey<Curve>> {
-    let vk_path = format!("{resources_folder}{VK_FILENAME}");
-    let zkey_path = format!("{resources_folder}{ZKEY_FILENAME}");
+    let vk = RESOURCES_DIR.get_file(Path::new(resources_folder).join(VK_FILENAME));
+    let zkey = RESOURCES_DIR.get_file(Path::new(resources_folder).join(ZKEY_FILENAME));
 
     let verifying_key: VerifyingKey<Curve>;
-
-    if Path::new(&vk_path).exists() {
-        verifying_key = vk_from_json(&vk_path);
+    if let Some(vk) = vk {
+        verifying_key = vk_from_json(vk.contents_utf8().ok_or(Report::msg(
+            "Could not read verification key from JSON file!",
+        ))?)?;
         Ok(verifying_key)
-    } else if Path::new(&zkey_path).exists() {
+    } else if let Some(_zkey) = zkey {
         let (proving_key, _matrices) = zkey_from_folder(resources_folder)?;
         verifying_key = proving_key.vk;
         Ok(verifying_key)
     } else {
-        Err(Error::new(
-            ErrorKind::NotFound,
-            "No proving/verification key found!",
-        ))
+        Err(Report::msg("No proving/verification key found!"))
     }
 }
 
@@ -121,129 +119,150 @@ static WITNESS_CALCULATOR: OnceCell<Mutex<WitnessCalculator>> = OnceCell::new();
 
 // Initializes the witness calculator using a bytes vector
 #[cfg(not(target_arch = "wasm32"))]
-pub fn circom_from_raw(wasm_buffer: Vec<u8>) -> &'static Mutex<WitnessCalculator> {
-    WITNESS_CALCULATOR.get_or_init(|| {
+pub fn circom_from_raw(wasm_buffer: Vec<u8>) -> Result<&'static Mutex<WitnessCalculator>> {
+    WITNESS_CALCULATOR.get_or_try_init(|| {
         let store = Store::default();
-        let module = Module::new(&store, wasm_buffer).unwrap();
-        let result =
-            WitnessCalculator::from_module(module).expect("Failed to create witness calculator");
-        Mutex::new(result)
+        let module = Module::new(&store, wasm_buffer)?;
+        let result = WitnessCalculator::from_module(module)?;
+        Ok::<Mutex<WitnessCalculator>, Report>(Mutex::new(result))
     })
 }
 
 // Initializes the witness calculator
 #[cfg(not(target_arch = "wasm32"))]
-pub fn circom_from_folder(resources_folder: &str) -> &'static Mutex<WitnessCalculator> {
+pub fn circom_from_folder(resources_folder: &str) -> Result<&'static Mutex<WitnessCalculator>> {
     // We read the wasm file
-    let wasm_path = format!("{resources_folder}{WASM_FILENAME}");
-    let wasm_buffer = std::fs::read(&wasm_path).unwrap();
-    circom_from_raw(wasm_buffer)
+    let wasm = RESOURCES_DIR.get_file(Path::new(resources_folder).join(WASM_FILENAME));
+
+    if let Some(wasm) = wasm {
+        let wasm_buffer = wasm.contents();
+        circom_from_raw(wasm_buffer.to_vec())
+    } else {
+        Err(Report::msg("No wasm file found!"))
+    }
 }
 
 // The following function implementations are taken/adapted from https://github.com/gakonst/ark-circom/blob/1732e15d6313fe176b0b1abb858ac9e095d0dbd7/src/zkey.rs
 
 // Utilities to convert a json verification key in a groth16::VerificationKey
-fn fq_from_str(s: &str) -> Fq {
-    Fq::try_from(BigUint::from_str(s).unwrap()).unwrap()
+fn fq_from_str(s: &str) -> Result<Fq> {
+    Ok(Fq::try_from(BigUint::from_str(s)?)?)
 }
 
 // Extracts the element in G1 corresponding to its JSON serialization
-fn json_to_g1(json: &Value, key: &str) -> G1Affine {
+fn json_to_g1(json: &Value, key: &str) -> Result<G1Affine> {
     let els: Vec<String> = json
         .get(key)
-        .unwrap()
+        .ok_or(Report::msg("no json value"))?
         .as_array()
-        .unwrap()
+        .ok_or(Report::msg("value not an array"))?
         .iter()
-        .map(|i| i.as_str().unwrap().to_string())
-        .collect();
-    G1Affine::from(G1Projective::new(
-        fq_from_str(&els[0]),
-        fq_from_str(&els[1]),
-        fq_from_str(&els[2]),
-    ))
+        .map(|i| i.as_str().ok_or(Report::msg("element is not a string")))
+        .map(|x| x.map(|v| v.to_owned()))
+        .collect::<Result<Vec<String>>>()?;
+
+    Ok(G1Affine::from(G1Projective::new(
+        fq_from_str(&els[0])?,
+        fq_from_str(&els[1])?,
+        fq_from_str(&els[2])?,
+    )))
 }
 
 // Extracts the vector of G1 elements corresponding to its JSON serialization
-fn json_to_g1_vec(json: &Value, key: &str) -> Vec<G1Affine> {
+fn json_to_g1_vec(json: &Value, key: &str) -> Result<Vec<G1Affine>> {
     let els: Vec<Vec<String>> = json
         .get(key)
-        .unwrap()
+        .ok_or(Report::msg("no json value"))?
         .as_array()
-        .unwrap()
+        .ok_or(Report::msg("value not an array"))?
         .iter()
         .map(|i| {
             i.as_array()
-                .unwrap()
-                .iter()
-                .map(|x| x.as_str().unwrap().to_string())
-                .collect::<Vec<String>>()
+                .ok_or(Report::msg("element is not an array"))
+                .and_then(|array| {
+                    array
+                        .iter()
+                        .map(|x| x.as_str().ok_or(Report::msg("element is not a string")))
+                        .map(|x| x.map(|v| v.to_owned()))
+                        .collect::<Result<Vec<String>>>()
+                })
         })
-        .collect();
+        .collect::<Result<Vec<Vec<String>>>>()?;
 
-    els.iter()
-        .map(|coords| {
-            G1Affine::from(G1Projective::new(
-                fq_from_str(&coords[0]),
-                fq_from_str(&coords[1]),
-                fq_from_str(&coords[2]),
-            ))
-        })
-        .collect()
+    let mut res = vec![];
+    for coords in els {
+        res.push(G1Affine::from(G1Projective::new(
+            fq_from_str(&coords[0])?,
+            fq_from_str(&coords[1])?,
+            fq_from_str(&coords[2])?,
+        )))
+    }
+
+    Ok(res)
 }
 
 // Extracts the element in G2 corresponding to its JSON serialization
-fn json_to_g2(json: &Value, key: &str) -> G2Affine {
+fn json_to_g2(json: &Value, key: &str) -> Result<G2Affine> {
     let els: Vec<Vec<String>> = json
         .get(key)
-        .unwrap()
+        .ok_or(Report::msg("no json value"))?
         .as_array()
-        .unwrap()
+        .ok_or(Report::msg("value not an array"))?
         .iter()
         .map(|i| {
             i.as_array()
-                .unwrap()
-                .iter()
-                .map(|x| x.as_str().unwrap().to_string())
-                .collect::<Vec<String>>()
+                .ok_or(Report::msg("element is not an array"))
+                .and_then(|array| {
+                    array
+                        .iter()
+                        .map(|x| x.as_str().ok_or(Report::msg("element is not a string")))
+                        .map(|x| x.map(|v| v.to_owned()))
+                        .collect::<Result<Vec<String>>>()
+                })
         })
-        .collect();
+        .collect::<Result<Vec<Vec<String>>>>()?;
 
-    let x = Fq2::new(fq_from_str(&els[0][0]), fq_from_str(&els[0][1]));
-    let y = Fq2::new(fq_from_str(&els[1][0]), fq_from_str(&els[1][1]));
-    let z = Fq2::new(fq_from_str(&els[2][0]), fq_from_str(&els[2][1]));
-    G2Affine::from(G2Projective::new(x, y, z))
+    let x = Fq2::new(fq_from_str(&els[0][0])?, fq_from_str(&els[0][1])?);
+    let y = Fq2::new(fq_from_str(&els[1][0])?, fq_from_str(&els[1][1])?);
+    let z = Fq2::new(fq_from_str(&els[2][0])?, fq_from_str(&els[2][1])?);
+    Ok(G2Affine::from(G2Projective::new(x, y, z)))
 }
 
 // Converts JSON to a VerifyingKey
-fn to_verifying_key(json: serde_json::Value) -> VerifyingKey<Curve> {
-    VerifyingKey {
-        alpha_g1: json_to_g1(&json, "vk_alpha_1"),
-        beta_g2: json_to_g2(&json, "vk_beta_2"),
-        gamma_g2: json_to_g2(&json, "vk_gamma_2"),
-        delta_g2: json_to_g2(&json, "vk_delta_2"),
-        gamma_abc_g1: json_to_g1_vec(&json, "IC"),
-    }
+fn to_verifying_key(json: serde_json::Value) -> Result<VerifyingKey<Curve>> {
+    Ok(VerifyingKey {
+        alpha_g1: json_to_g1(&json, "vk_alpha_1")?,
+        beta_g2: json_to_g2(&json, "vk_beta_2")?,
+        gamma_g2: json_to_g2(&json, "vk_gamma_2")?,
+        delta_g2: json_to_g2(&json, "vk_delta_2")?,
+        gamma_abc_g1: json_to_g1_vec(&json, "IC")?,
+    })
 }
 
 // Computes the verification key from its JSON serialization
-fn vk_from_json(vk_path: &str) -> VerifyingKey<Curve> {
-    let json = std::fs::read_to_string(vk_path).unwrap();
-    let json: Value = serde_json::from_str(&json).unwrap();
-
+fn vk_from_json(vk: &str) -> Result<VerifyingKey<Curve>> {
+    let json: Value = serde_json::from_str(vk)?;
     to_verifying_key(json)
 }
 
 // Computes the verification key from a bytes vector containing its JSON serialization
-fn vk_from_vector(vk: &[u8]) -> VerifyingKey<Curve> {
-    let json = String::from_utf8(vk.to_vec()).expect("Found invalid UTF-8");
-    let json: Value = serde_json::from_str(&json).unwrap();
+fn vk_from_vector(vk: &[u8]) -> Result<VerifyingKey<Curve>> {
+    let json = String::from_utf8(vk.to_vec())?;
+    let json: Value = serde_json::from_str(&json)?;
 
     to_verifying_key(json)
 }
 
 // Checks verification key to be correct with respect to proving key
-pub fn check_vk_from_zkey(resources_folder: &str, verifying_key: VerifyingKey<Curve>) {
-    let (proving_key, _matrices) = zkey_from_folder(resources_folder).unwrap();
-    assert_eq!(proving_key.vk, verifying_key);
+#[cfg(not(target_arch = "wasm32"))]
+pub fn check_vk_from_zkey(
+    resources_folder: &str,
+    verifying_key: VerifyingKey<Curve>,
+) -> Result<()> {
+    let (proving_key, _matrices) = zkey_from_folder(resources_folder)?;
+    if proving_key.vk == verifying_key {
+        Ok(())
+    } else {
+        Err(Report::msg("verifying_keys are not equal"))
+    }
 }

rln/src/ffi.rs

@@ -2,7 +2,7 @@
 
 use std::slice;
 
-use crate::public::RLN;
+use crate::public::{hash as public_hash, poseidon_hash as public_poseidon_hash, RLN};
 
 // Macro to call methods with arbitrary amount of arguments,
 // First argument to the macro is context,
@@ -53,6 +53,28 @@ macro_rules! call_with_output_arg {
                 false
             }
         }
+    };
+
+}
+
+// Macro to call methods with arbitrary amount of arguments,
+// which are not implemented in a ctx RLN object
+// First argument is the method to call
+// Second argument is the output buffer argument
+// The remaining arguments are all other inputs to the method
+macro_rules! no_ctx_call_with_output_arg {
+    ($method:ident, $output_arg:expr, $( $arg:expr ),* ) => {
+        {
+            let mut output_data: Vec<u8> = Vec::new();
+            if $method($($arg.process()),*, &mut output_data).is_ok() {
+                unsafe { *$output_arg = Buffer::from(&output_data[..]) };
+                std::mem::forget(output_data);
+                true
+            } else {
+                std::mem::forget(output_data);
+                false
+            }
+        }
     }
 }
 
@@ -149,9 +171,12 @@ impl<'a> From<&Buffer> for &'a [u8] {
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[no_mangle]
 pub extern "C" fn new(tree_height: usize, input_buffer: *const Buffer, ctx: *mut *mut RLN) -> bool {
-    let rln = RLN::new(tree_height, input_buffer.process());
-    unsafe { *ctx = Box::into_raw(Box::new(rln)) };
-    true
+    if let Ok(rln) = RLN::new(tree_height, input_buffer.process()) {
+        unsafe { *ctx = Box::into_raw(Box::new(rln)) };
+        true
+    } else {
+        false
+    }
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
@@ -163,14 +188,17 @@ pub extern "C" fn new_with_params(
     vk_buffer: *const Buffer,
     ctx: *mut *mut RLN,
 ) -> bool {
-    let rln = RLN::new_with_params(
+    if let Ok(rln) = RLN::new_with_params(
         tree_height,
         circom_buffer.process().to_vec(),
         zkey_buffer.process().to_vec(),
         vk_buffer.process().to_vec(),
-    );
-    unsafe { *ctx = Box::into_raw(Box::new(rln)) };
-    true
+    ) {
+        unsafe { *ctx = Box::into_raw(Box::new(rln)) };
+        true
+    } else {
+        false
+    }
 }
 
 ////////////////////////////////////////////////////////
@@ -342,10 +370,12 @@ pub extern "C" fn recover_id_secret(
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[no_mangle]
-pub extern "C" fn hash(
-    ctx: *mut RLN,
-    input_buffer: *const Buffer,
-    output_buffer: *mut Buffer,
-) -> bool {
-    call_with_output_arg!(ctx, hash, output_buffer, input_buffer)
+pub extern "C" fn hash(input_buffer: *const Buffer, output_buffer: *mut Buffer) -> bool {
+    no_ctx_call_with_output_arg!(public_hash, output_buffer, input_buffer)
+}
+
+#[allow(clippy::not_unsafe_ptr_arg_deref)]
+#[no_mangle]
+pub extern "C" fn poseidon_hash(input_buffer: *const Buffer, output_buffer: *mut Buffer) -> bool {
+    no_ctx_call_with_output_arg!(public_poseidon_hash, output_buffer, input_buffer)
 }

rln/src/hashers.rs

@@ -1,7 +1,8 @@
 // This crate instantiate the Poseidon hash algorithm
 
-use crate::circuit::Fr;
+use crate::{circuit::Fr, utils::bytes_le_to_fr};
 use once_cell::sync::Lazy;
+use tiny_keccak::{Hasher, Keccak};
 use utils::poseidon::Poseidon;
 
 // These indexed constants hardcodes the supported round parameters tuples (t, RF, RN, SKIP_MATRICES) for the Bn254 scalar field
@@ -26,3 +27,17 @@ pub fn poseidon_hash(input: &[Fr]) -> Fr {
         .hash(input.to_vec())
         .expect("hash with fixed input size can't fail")
 }
+
+// Hashes arbitrary signal to the underlying prime field
+pub fn hash_to_field(signal: &[u8]) -> Fr {
+    // We hash the input signal using Keccak256
+    // (note that a bigger curve order might require a bigger hash blocksize)
+    let mut hash = [0; 32];
+    let mut hasher = Keccak::v256();
+    hasher.update(signal);
+    hasher.finalize(&mut hash);
+
+    // We export the hash as a field element
+    let (el, _) = bytes_le_to_fr(hash.as_ref());
+    el
+}

rln/src/lib.rs

@@ -1,7 +1,7 @@
 #![allow(dead_code)]
 
 pub mod circuit;
-pub mod poseidon_hash;
+pub mod hashers;
 pub mod poseidon_tree;
 pub mod protocol;
 pub mod public;

rln/src/poseidon_tree.rs

@@ -3,10 +3,15 @@
 // Implementation inspired by https://github.com/worldcoin/semaphore-rs/blob/d462a4372f1fd9c27610f2acfe4841fab1d396aa/src/poseidon_tree.rs (no differences)
 
 use crate::circuit::Fr;
-use crate::poseidon_hash::poseidon_hash;
+use crate::hashers::poseidon_hash;
 use cfg_if::cfg_if;
 use utils::merkle_tree::*;
 
+#[cfg(feature = "pmtree-ft")]
+use crate::utils::{bytes_le_to_fr, fr_to_bytes_le};
+#[cfg(feature = "pmtree-ft")]
+use pmtree::*;
+
 // The zerokit RLN default Merkle tree implementation is the OptimalMerkleTree.
 // To switch to FullMerkleTree implementation, it is enough to enable the fullmerkletree feature
 
@@ -36,3 +41,26 @@ impl utils::merkle_tree::Hasher for PoseidonHash {
         poseidon_hash(inputs)
     }
 }
+
+#[cfg(feature = "pmtree-ft")]
+// The pmtree Hasher trait used by pmtree Merkle tree
+impl pmtree::Hasher for PoseidonHash {
+    type Fr = Fr;
+
+    fn default_leaf() -> Self::Fr {
+        Fr::from(0)
+    }
+
+    fn serialize(value: Self::Fr) -> Value {
+        fr_to_bytes_le(&value)
+    }
+
+    fn deserialize(value: Value) -> Self::Fr {
+        let (fr, _) = bytes_le_to_fr(&value);
+        fr
+    }
+
+    fn hash(inputs: &[Self::Fr]) -> Self::Fr {
+        poseidon_hash(inputs)
+    }
+}

rln/src/protocol.rs

@@ -1,14 +1,11 @@
 // This crate collects all the underlying primitives used to implement RLN
 
 use ark_circom::{CircomReduction, WitnessCalculator};
-use ark_groth16::{
-    create_proof_with_reduction_and_matrices, prepare_verifying_key,
-    verify_proof as ark_verify_proof, Proof as ArkProof, ProvingKey, VerifyingKey,
-};
+use ark_groth16::{prepare_verifying_key, Groth16, Proof as ArkProof, ProvingKey, VerifyingKey};
 use ark_relations::r1cs::ConstraintMatrices;
 use ark_relations::r1cs::SynthesisError;
 use ark_std::{rand::thread_rng, UniformRand};
-use color_eyre::Result;
+use color_eyre::{Report, Result};
 use num_bigint::BigInt;
 use rand::{Rng, SeedableRng};
 use rand_chacha::ChaCha20Rng;
@@ -20,11 +17,13 @@ use thiserror::Error;
 use tiny_keccak::{Hasher as _, Keccak};
 
 use crate::circuit::{Curve, Fr};
-use crate::poseidon_hash::poseidon_hash;
+use crate::hashers::hash_to_field;
+use crate::hashers::poseidon_hash;
 use crate::poseidon_tree::*;
 use crate::public::RLN_IDENTIFIER;
 use crate::utils::*;
 use cfg_if::cfg_if;
+use utils::{ZerokitMerkleProof, ZerokitMerkleTree};
 
 ///////////////////////////////////////////////////////
 // RLN Witness data structure and utility functions
@@ -53,82 +52,84 @@ pub struct RLNProofValues {
 }
 
 pub fn serialize_field_element(element: Fr) -> Vec<u8> {
-    return fr_to_bytes_le(&element);
+    fr_to_bytes_le(&element)
 }
 
 pub fn deserialize_field_element(serialized: Vec<u8>) -> Fr {
     let (element, _) = bytes_le_to_fr(&serialized);
 
-    return element;
+    element
 }
 
 pub fn deserialize_identity_pair(serialized: Vec<u8>) -> (Fr, Fr) {
     let (identity_secret_hash, read) = bytes_le_to_fr(&serialized);
-    let (id_commitment, _) = bytes_le_to_fr(&serialized[read..].to_vec());
+    let (id_commitment, _) = bytes_le_to_fr(&serialized[read..]);
 
-    return (identity_secret_hash, id_commitment);
+    (identity_secret_hash, id_commitment)
 }
 
 pub fn deserialize_identity_tuple(serialized: Vec<u8>) -> (Fr, Fr, Fr, Fr) {
     let mut all_read = 0;
 
-    let (identity_trapdoor, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (identity_trapdoor, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (identity_nullifier, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (identity_nullifier, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (identity_secret_hash, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (identity_secret_hash, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (identity_commitment, _) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (identity_commitment, _) = bytes_le_to_fr(&serialized[all_read..]);
 
-    return (
+    (
         identity_trapdoor,
         identity_nullifier,
         identity_secret_hash,
         identity_commitment,
-    );
+    )
 }
 
-pub fn serialize_witness(rln_witness: &RLNWitnessInput) -> Vec<u8> {
+pub fn serialize_witness(rln_witness: &RLNWitnessInput) -> Result<Vec<u8>> {
     let mut serialized: Vec<u8> = Vec::new();
 
     serialized.append(&mut fr_to_bytes_le(&rln_witness.identity_secret));
-    serialized.append(&mut vec_fr_to_bytes_le(&rln_witness.path_elements));
-    serialized.append(&mut vec_u8_to_bytes_le(&rln_witness.identity_path_index));
+    serialized.append(&mut vec_fr_to_bytes_le(&rln_witness.path_elements)?);
+    serialized.append(&mut vec_u8_to_bytes_le(&rln_witness.identity_path_index)?);
     serialized.append(&mut fr_to_bytes_le(&rln_witness.x));
     serialized.append(&mut fr_to_bytes_le(&rln_witness.epoch));
     serialized.append(&mut fr_to_bytes_le(&rln_witness.rln_identifier));
 
-    serialized
+    Ok(serialized)
 }
 
-pub fn deserialize_witness(serialized: &[u8]) -> (RLNWitnessInput, usize) {
+pub fn deserialize_witness(serialized: &[u8]) -> Result<(RLNWitnessInput, usize)> {
     let mut all_read: usize = 0;
 
-    let (identity_secret, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (identity_secret, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (path_elements, read) = bytes_le_to_vec_fr(&serialized[all_read..].to_vec());
+    let (path_elements, read) = bytes_le_to_vec_fr(&serialized[all_read..])?;
     all_read += read;
 
-    let (identity_path_index, read) = bytes_le_to_vec_u8(&serialized[all_read..].to_vec());
+    let (identity_path_index, read) = bytes_le_to_vec_u8(&serialized[all_read..])?;
     all_read += read;
 
-    let (x, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (x, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (epoch, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (epoch, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (rln_identifier, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (rln_identifier, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
     // TODO: check rln_identifier against public::RLN_IDENTIFIER
-    assert_eq!(serialized.len(), all_read);
+    if serialized.len() != all_read {
+        return Err(Report::msg("serialized length is not equal to all_read"));
+    }
 
-    (
+    Ok((
         RLNWitnessInput {
             identity_secret,
             path_elements,
@@ -138,7 +139,7 @@ pub fn deserialize_witness(serialized: &[u8]) -> (RLNWitnessInput, usize) {
             rln_identifier,
         },
         all_read,
-    )
+    ))
 }
 
 // This function deserializes input for kilic's rln generate_proof public API
@@ -148,24 +149,24 @@ pub fn deserialize_witness(serialized: &[u8]) -> (RLNWitnessInput, usize) {
 pub fn proof_inputs_to_rln_witness(
     tree: &mut PoseidonTree,
     serialized: &[u8],
-) -> (RLNWitnessInput, usize) {
+) -> Result<(RLNWitnessInput, usize)> {
     let mut all_read: usize = 0;
 
-    let (identity_secret, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (identity_secret, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let id_index = u64::from_le_bytes(serialized[all_read..all_read + 8].try_into().unwrap());
+    let id_index = usize::from_le_bytes(serialized[all_read..all_read + 8].try_into()?);
     all_read += 8;
 
-    let (epoch, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (epoch, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let signal_len = u64::from_le_bytes(serialized[all_read..all_read + 8].try_into().unwrap());
+    let signal_len = usize::from_le_bytes(serialized[all_read..all_read + 8].try_into()?);
     all_read += 8;
 
-    let signal: Vec<u8> = serialized[all_read..all_read + (signal_len as usize)].to_vec();
+    let signal: Vec<u8> = serialized[all_read..all_read + signal_len].to_vec();
 
-    let merkle_proof = tree.proof(id_index as usize).expect("proof should exist");
+    let merkle_proof = tree.proof(id_index).expect("proof should exist");
     let path_elements = merkle_proof.get_path_elements();
     let identity_path_index = merkle_proof.get_path_index();
 
@@ -173,7 +174,7 @@ pub fn proof_inputs_to_rln_witness(
 
     let rln_identifier = hash_to_field(RLN_IDENTIFIER);
 
-    (
+    Ok((
         RLNWitnessInput {
             identity_secret,
             path_elements,
@@ -183,45 +184,48 @@ pub fn proof_inputs_to_rln_witness(
             rln_identifier,
         },
         all_read,
-    )
+    ))
 }
 
-pub fn rln_witness_from_json(input_json_str: &str) -> RLNWitnessInput {
+pub fn rln_witness_from_json(input_json_str: &str) -> Result<RLNWitnessInput> {
     let input_json: serde_json::Value =
         serde_json::from_str(input_json_str).expect("JSON was not well-formatted");
 
-    let identity_secret = str_to_fr(&input_json["identity_secret"].to_string(), 10);
+    let identity_secret = str_to_fr(&input_json["identity_secret"].to_string(), 10)?;
 
     let path_elements = input_json["path_elements"]
         .as_array()
-        .unwrap()
+        .ok_or(Report::msg("not an array"))?
         .iter()
         .map(|v| str_to_fr(&v.to_string(), 10))
-        .collect();
+        .collect::<Result<_>>()?;
 
-    let identity_path_index = input_json["identity_path_index"]
+    let identity_path_index_array = input_json["identity_path_index"]
         .as_array()
-        .unwrap()
-        .iter()
-        .map(|v| v.as_u64().unwrap() as u8)
-        .collect();
+        .ok_or(Report::msg("not an arrray"))?;
 
-    let x = str_to_fr(&input_json["x"].to_string(), 10);
+    let mut identity_path_index: Vec<u8> = vec![];
 
-    let epoch = str_to_fr(&input_json["epoch"].to_string(), 16);
+    for v in identity_path_index_array {
+        identity_path_index.push(v.as_u64().ok_or(Report::msg("not a u64 value"))? as u8);
+    }
 
-    let rln_identifier = str_to_fr(&input_json["rln_identifier"].to_string(), 10);
+    let x = str_to_fr(&input_json["x"].to_string(), 10)?;
+
+    let epoch = str_to_fr(&input_json["epoch"].to_string(), 16)?;
+
+    let rln_identifier = str_to_fr(&input_json["rln_identifier"].to_string(), 10)?;
 
     // TODO: check rln_identifier against public::RLN_IDENTIFIER
 
-    RLNWitnessInput {
+    Ok(RLNWitnessInput {
         identity_secret,
         path_elements,
         identity_path_index,
         x,
         epoch,
         rln_identifier,
-    }
+    })
 }
 
 pub fn rln_witness_from_values(
@@ -317,22 +321,22 @@ pub fn serialize_proof_values(rln_proof_values: &RLNProofValues) -> Vec<u8> {
 pub fn deserialize_proof_values(serialized: &[u8]) -> (RLNProofValues, usize) {
     let mut all_read: usize = 0;
 
-    let (root, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (root, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (epoch, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (epoch, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (x, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (x, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (y, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (y, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (nullifier, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (nullifier, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
-    let (rln_identifier, read) = bytes_le_to_fr(&serialized[all_read..].to_vec());
+    let (rln_identifier, read) = bytes_le_to_fr(&serialized[all_read..]);
     all_read += read;
 
     (
@@ -354,29 +358,26 @@ pub fn prepare_prove_input(
     epoch: Fr,
     signal: &[u8],
 ) -> Vec<u8> {
-    let signal_len = u64::try_from(signal.len()).unwrap();
-
     let mut serialized: Vec<u8> = Vec::new();
 
     serialized.append(&mut fr_to_bytes_le(&identity_secret));
-    serialized.append(&mut id_index.to_le_bytes().to_vec());
+    serialized.append(&mut normalize_usize(id_index));
     serialized.append(&mut fr_to_bytes_le(&epoch));
-    serialized.append(&mut signal_len.to_le_bytes().to_vec());
+    serialized.append(&mut normalize_usize(signal.len()));
     serialized.append(&mut signal.to_vec());
 
-    return serialized;
+    serialized
 }
 
+#[allow(clippy::redundant_clone)]
 pub fn prepare_verify_input(proof_data: Vec<u8>, signal: &[u8]) -> Vec<u8> {
-    let signal_len = u64::try_from(signal.len()).unwrap();
-
     let mut serialized: Vec<u8> = Vec::new();
 
     serialized.append(&mut proof_data.clone());
-    serialized.append(&mut signal_len.to_le_bytes().to_vec());
+    serialized.append(&mut normalize_usize(signal.len()));
     serialized.append(&mut signal.to_vec());
 
-    return serialized;
+    serialized
 }
 
 ///////////////////////////////////////////////////////
@@ -483,20 +484,6 @@ pub fn extended_seeded_keygen(signal: &[u8]) -> (Fr, Fr, Fr, Fr) {
     )
 }
 
-// Hashes arbitrary signal to the underlying prime field
-pub fn hash_to_field(signal: &[u8]) -> Fr {
-    // We hash the input signal using Keccak256
-    // (note that a bigger curve order might require a bigger hash blocksize)
-    let mut hash = [0; 32];
-    let mut hasher = Keccak::v256();
-    hasher.update(signal);
-    hasher.finalize(&mut hash);
-
-    // We export the hash as a field element
-    let (el, _) = bytes_le_to_fr(hash.as_ref());
-    el
-}
-
 pub fn compute_id_secret(
     share1: (Fr, Fr),
     share2: (Fr, Fr),
@@ -519,9 +506,9 @@ pub fn compute_id_secret(
 
     if a_1 == computed_a_1 {
         // We successfully recovered the identity secret
-        return Ok(a_0);
+        Ok(a_0)
     } else {
-        return Err("Cannot recover identity_secret_hash from provided shares".into());
+        Err("Cannot recover identity_secret_hash from provided shares".into())
     }
 }
 
@@ -532,33 +519,36 @@ pub fn compute_id_secret(
 #[derive(Error, Debug)]
 pub enum ProofError {
     #[error("Error reading circuit key: {0}")]
-    CircuitKeyError(#[from] std::io::Error),
+    CircuitKeyError(#[from] Report),
     #[error("Error producing witness: {0}")]
-    WitnessError(color_eyre::Report),
+    WitnessError(Report),
     #[error("Error producing proof: {0}")]
     SynthesisError(#[from] SynthesisError),
 }
 
-fn calculate_witness_element<E: ark_ec::PairingEngine>(witness: Vec<BigInt>) -> Result<Vec<E::Fr>> {
-    use ark_ff::{FpParameters, PrimeField};
-    let modulus = <<E::Fr as PrimeField>::Params as FpParameters>::MODULUS;
+fn calculate_witness_element<E: ark_ec::pairing::Pairing>(
+    witness: Vec<BigInt>,
+) -> Result<Vec<E::ScalarField>> {
+    use ark_ff::PrimeField;
+    let modulus = <E::ScalarField as PrimeField>::MODULUS;
 
     // convert it to field elements
     use num_traits::Signed;
-    let witness = witness
-        .into_iter()
-        .map(|w| {
-            let w = if w.sign() == num_bigint::Sign::Minus {
-                // Need to negate the witness element if negative
-                modulus.into() - w.abs().to_biguint().unwrap()
-            } else {
-                w.to_biguint().unwrap()
-            };
-            E::Fr::from(w)
-        })
-        .collect::<Vec<_>>();
+    let mut witness_vec = vec![];
+    for w in witness.into_iter() {
+        let w = if w.sign() == num_bigint::Sign::Minus {
+            // Need to negate the witness element if negative
+            modulus.into()
+                - w.abs()
+                    .to_biguint()
+                    .ok_or(Report::msg("not a biguint value"))?
+        } else {
+            w.to_biguint().ok_or(Report::msg("not a biguint value"))?
+        };
+        witness_vec.push(E::ScalarField::from(w))
+    }
 
-    Ok(witness)
+    Ok(witness_vec)
 }
 
 pub fn generate_proof_with_witness(
@@ -569,9 +559,8 @@ pub fn generate_proof_with_witness(
     #[cfg(debug_assertions)]
     let now = Instant::now();
 
-    let full_assignment = calculate_witness_element::<Curve>(witness)
-        .map_err(ProofError::WitnessError)
-        .unwrap();
+    let full_assignment =
+        calculate_witness_element::<Curve>(witness).map_err(ProofError::WitnessError)?;
 
     #[cfg(debug_assertions)]
     println!("witness generation took: {:.2?}", now.elapsed());
@@ -585,7 +574,7 @@ pub fn generate_proof_with_witness(
     #[cfg(debug_assertions)]
     let now = Instant::now();
 
-    let proof = create_proof_with_reduction_and_matrices::<_, CircomReduction>(
+    let proof = Groth16::<_, CircomReduction>::create_proof_with_reduction_and_matrices(
         &proving_key.0,
         r,
         s,
@@ -593,8 +582,7 @@ pub fn generate_proof_with_witness(
         proving_key.1.num_instance_variables,
         proving_key.1.num_constraints,
         full_assignment.as_slice(),
-    )
-    .unwrap();
+    )?;
 
     #[cfg(debug_assertions)]
     println!("proof generation took: {:.2?}", now.elapsed());
@@ -602,14 +590,16 @@ pub fn generate_proof_with_witness(
     Ok(proof)
 }
 
-pub fn inputs_for_witness_calculation(rln_witness: &RLNWitnessInput) -> [(&str, Vec<BigInt>); 6] {
+pub fn inputs_for_witness_calculation(
+    rln_witness: &RLNWitnessInput,
+) -> Result<[(&str, Vec<BigInt>); 6]> {
     // We confert the path indexes to field elements
     // TODO: check if necessary
     let mut path_elements = Vec::new();
-    rln_witness
-        .path_elements
-        .iter()
-        .for_each(|v| path_elements.push(to_bigint(v)));
+
+    for v in rln_witness.path_elements.iter() {
+        path_elements.push(to_bigint(v)?);
+    }
 
     let mut identity_path_index = Vec::new();
     rln_witness
@@ -617,20 +607,20 @@ pub fn inputs_for_witness_calculation(rln_witness: &RLNWitnessInput) -> [(&str,
         .iter()
         .for_each(|v| identity_path_index.push(BigInt::from(*v)));
 
-    [
+    Ok([
         (
             "identity_secret",
-            vec![to_bigint(&rln_witness.identity_secret)],
+            vec![to_bigint(&rln_witness.identity_secret)?],
         ),
         ("path_elements", path_elements),
         ("identity_path_index", identity_path_index),
-        ("x", vec![to_bigint(&rln_witness.x)]),
-        ("epoch", vec![to_bigint(&rln_witness.epoch)]),
+        ("x", vec![to_bigint(&rln_witness.x)?]),
+        ("epoch", vec![to_bigint(&rln_witness.epoch)?]),
         (
             "rln_identifier",
-            vec![to_bigint(&rln_witness.rln_identifier)],
+            vec![to_bigint(&rln_witness.rln_identifier)?],
         ),
-    ]
+    ])
 }
 
 /// Generates a RLN proof
@@ -644,7 +634,7 @@ pub fn generate_proof(
     proving_key: &(ProvingKey<Curve>, ConstraintMatrices<Fr>),
     rln_witness: &RLNWitnessInput,
 ) -> Result<ArkProof<Curve>, ProofError> {
-    let inputs = inputs_for_witness_calculation(rln_witness)
+    let inputs = inputs_for_witness_calculation(rln_witness)?
         .into_iter()
         .map(|(name, values)| (name.to_string(), values));
 
@@ -678,7 +668,7 @@ pub fn generate_proof(
     #[cfg(debug_assertions)]
     let now = Instant::now();
 
-    let proof = create_proof_with_reduction_and_matrices::<_, CircomReduction>(
+    let proof = Groth16::<_, CircomReduction>::create_proof_with_reduction_and_matrices(
         &proving_key.0,
         r,
         s,
@@ -723,7 +713,7 @@ pub fn verify_proof(
     #[cfg(debug_assertions)]
     let now = Instant::now();
 
-    let verified = ark_verify_proof(&pvk, proof, &inputs)?;
+    let verified = Groth16::<_, CircomReduction>::verify_proof(&pvk, proof, &inputs)?;
 
     #[cfg(debug_assertions)]
     println!("verify took: {:.2?}", now.elapsed());
@@ -735,12 +725,12 @@ pub fn verify_proof(
 ///
 /// Returns a JSON object containing the inputs necessary to calculate
 /// the witness with CIRCOM on javascript
-pub fn get_json_inputs(rln_witness: &RLNWitnessInput) -> serde_json::Value {
+pub fn get_json_inputs(rln_witness: &RLNWitnessInput) -> Result<serde_json::Value> {
     let mut path_elements = Vec::new();
-    rln_witness
-        .path_elements
-        .iter()
-        .for_each(|v| path_elements.push(to_bigint(v).to_str_radix(10)));
+
+    for v in rln_witness.path_elements.iter() {
+        path_elements.push(to_bigint(v)?.to_str_radix(10));
+    }
 
     let mut identity_path_index = Vec::new();
     rln_witness
@@ -749,13 +739,13 @@ pub fn get_json_inputs(rln_witness: &RLNWitnessInput) -> serde_json::Value {
         .for_each(|v| identity_path_index.push(BigInt::from(*v).to_str_radix(10)));
 
     let inputs = serde_json::json!({
-        "identity_secret": to_bigint(&rln_witness.identity_secret).to_str_radix(10),
+        "identity_secret": to_bigint(&rln_witness.identity_secret)?.to_str_radix(10),
         "path_elements": path_elements,
         "identity_path_index": identity_path_index,
-        "x": to_bigint(&rln_witness.x).to_str_radix(10),
-        "epoch":  format!("0x{:064x}", to_bigint(&rln_witness.epoch)),
-        "rln_identifier": to_bigint(&rln_witness.rln_identifier).to_str_radix(10),
+        "x": to_bigint(&rln_witness.x)?.to_str_radix(10),
+        "epoch":  format!("0x{:064x}", to_bigint(&rln_witness.epoch)?),
+        "rln_identifier": to_bigint(&rln_witness.rln_identifier)?.to_str_radix(10),
     });
 
-    inputs
+    Ok(inputs)
 }

rln/src/public.rs

@@ -1,5 +1,5 @@
 use crate::circuit::{vk_from_raw, zkey_from_raw, Curve, Fr};
-use crate::poseidon_hash::poseidon_hash;
+use crate::hashers::{hash_to_field, poseidon_hash as utils_poseidon_hash};
 use crate::poseidon_tree::PoseidonTree;
 use crate::protocol::*;
 use crate::utils::*;
@@ -10,9 +10,11 @@ use ark_groth16::{ProvingKey, VerifyingKey};
 use ark_relations::r1cs::ConstraintMatrices;
 use ark_serialize::{CanonicalDeserialize, CanonicalSerialize, Read, Write};
 use cfg_if::cfg_if;
+use color_eyre::Result;
 use num_bigint::BigInt;
 use std::io::Cursor;
-use std::io::{self, Result};
+use utils::{ZerokitMerkleProof, ZerokitMerkleTree};
+// use rkyv::Deserialize;
 
 cfg_if! {
     if #[cfg(not(target_arch = "wasm32"))] {
@@ -36,8 +38,8 @@ pub const RLN_IDENTIFIER: &[u8] = b"zerokit/rln/010203040506070809";
 ///
 /// I/O is mostly done using writers and readers implementing `std::io::Write` and `std::io::Read`, respectively.
 pub struct RLN<'a> {
-    proving_key: Result<(ProvingKey<Curve>, ConstraintMatrices<Fr>)>,
-    verification_key: Result<VerifyingKey<Curve>>,
+    proving_key: (ProvingKey<Curve>, ConstraintMatrices<Fr>),
+    verification_key: VerifyingKey<Curve>,
     tree: PoseidonTree,
 
     // The witness calculator can't be loaded in zerokit. Since this struct
@@ -61,35 +63,35 @@ impl RLN<'_> {
     /// use std::io::Cursor;
     ///
     /// let tree_height = 20;
-    /// let resources = Cursor::new("./resources/tree_height_20/");
+    /// let resources = Cursor::new("tree_height_20");
     ///
     /// // We create a new RLN instance
     /// let mut rln = RLN::new(tree_height, resources);
     /// ```
     #[cfg(not(target_arch = "wasm32"))]
-    pub fn new<R: Read>(tree_height: usize, mut input_data: R) -> RLN<'static> {
+    pub fn new<R: Read>(tree_height: usize, mut input_data: R) -> Result<RLN<'static>> {
         // We read input
         let mut input: Vec<u8> = Vec::new();
-        input_data.read_to_end(&mut input).unwrap();
+        input_data.read_to_end(&mut input)?;
 
-        let resources_folder = String::from_utf8(input).expect("Found invalid UTF-8");
+        let resources_folder = String::from_utf8(input)?;
 
-        let witness_calculator = circom_from_folder(&resources_folder);
+        let witness_calculator = circom_from_folder(&resources_folder)?;
 
-        let proving_key = zkey_from_folder(&resources_folder);
-        let verification_key = vk_from_folder(&resources_folder);
+        let proving_key = zkey_from_folder(&resources_folder)?;
+        let verification_key = vk_from_folder(&resources_folder)?;
 
         // We compute a default empty tree
         let tree = PoseidonTree::default(tree_height);
 
-        RLN {
+        Ok(RLN {
             witness_calculator,
             proving_key,
             verification_key,
             tree,
             #[cfg(target_arch = "wasm32")]
             _marker: PhantomData,
-        }
+        })
     }
 
     /// Creates a new RLN object by passing circuit resources as byte vectors.
@@ -130,17 +132,17 @@ impl RLN<'_> {
         #[cfg(not(target_arch = "wasm32"))] circom_vec: Vec<u8>,
         zkey_vec: Vec<u8>,
         vk_vec: Vec<u8>,
-    ) -> RLN<'static> {
+    ) -> Result<RLN<'static>> {
         #[cfg(not(target_arch = "wasm32"))]
-        let witness_calculator = circom_from_raw(circom_vec);
+        let witness_calculator = circom_from_raw(circom_vec)?;
 
-        let proving_key = zkey_from_raw(&zkey_vec);
-        let verification_key = vk_from_raw(&vk_vec, &zkey_vec);
+        let proving_key = zkey_from_raw(&zkey_vec)?;
+        let verification_key = vk_from_raw(&vk_vec, &zkey_vec)?;
 
         // We compute a default empty tree
         let tree = PoseidonTree::default(tree_height);
 
-        RLN {
+        Ok(RLN {
             #[cfg(not(target_arch = "wasm32"))]
             witness_calculator,
             proving_key,
@@ -148,7 +150,7 @@ impl RLN<'_> {
             tree,
             #[cfg(target_arch = "wasm32")]
             _marker: PhantomData,
-        }
+        })
     }
 
     ////////////////////////////////////////////////////////
@@ -160,7 +162,7 @@ impl RLN<'_> {
     ///
     /// Input values are:
     /// - `tree_height`: the height of the Merkle tree.
-    pub fn set_tree(&mut self, tree_height: usize) -> io::Result<()> {
+    pub fn set_tree(&mut self, tree_height: usize) -> Result<()> {
         // We compute a default empty tree of desired height
         self.tree = PoseidonTree::default(tree_height);
 
@@ -187,7 +189,7 @@ impl RLN<'_> {
     /// let mut buffer = Cursor::new(serialize_field_element(id_commitment));
     /// rln.set_leaf(id_index, &mut buffer).unwrap();
     /// ```
-    pub fn set_leaf<R: Read>(&mut self, index: usize, mut input_data: R) -> io::Result<()> {
+    pub fn set_leaf<R: Read>(&mut self, index: usize, mut input_data: R) -> Result<()> {
         // We read input
         let mut leaf_byte: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut leaf_byte)?;
@@ -229,15 +231,15 @@ impl RLN<'_> {
     /// let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves));
     /// rln.set_leaves_from(index, &mut buffer).unwrap();
     /// ```
-    pub fn set_leaves_from<R: Read>(&mut self, index: usize, mut input_data: R) -> io::Result<()> {
+    pub fn set_leaves_from<R: Read>(&mut self, index: usize, mut input_data: R) -> Result<()> {
         // We read input
         let mut leaves_byte: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut leaves_byte)?;
 
-        let (leaves, _) = bytes_le_to_vec_fr(&leaves_byte);
+        let (leaves, _) = bytes_le_to_vec_fr(&leaves_byte)?;
 
         // We set the leaves
-        return self.tree.set_range(index, leaves);
+        self.tree.set_range(index, leaves)
     }
 
     /// Resets the tree state to default and sets multiple leaves starting from index 0.
@@ -246,12 +248,12 @@ impl RLN<'_> {
     ///
     /// Input values are:
     /// - `input_data`: a reader for the serialization of multiple leaf values (serialization done with [`rln::utils::vec_fr_to_bytes_le`](crate::utils::vec_fr_to_bytes_le))
-    pub fn init_tree_with_leaves<R: Read>(&mut self, input_data: R) -> io::Result<()> {
+    pub fn init_tree_with_leaves<R: Read>(&mut self, input_data: R) -> Result<()> {
         // reset the tree
         // NOTE: this requires the tree to be initialized with the correct height initially
         // TODO: accept tree_height as a parameter and initialize the tree with that height
         self.set_tree(self.tree.depth())?;
-        return self.set_leaves_from(0, input_data);
+        self.set_leaves_from(0, input_data)
     }
 
     /// Sets a leaf value at the next available never-set leaf index.
@@ -295,7 +297,7 @@ impl RLN<'_> {
     /// let mut buffer = Cursor::new(fr_to_bytes_le(&id_commitment));
     /// rln.set_next_leaf(&mut buffer).unwrap();
     /// ```
-    pub fn set_next_leaf<R: Read>(&mut self, mut input_data: R) -> io::Result<()> {
+    pub fn set_next_leaf<R: Read>(&mut self, mut input_data: R) -> Result<()> {
         // We read input
         let mut leaf_byte: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut leaf_byte)?;
@@ -320,7 +322,7 @@ impl RLN<'_> {
     /// let index = 10;
     /// rln.delete_leaf(index).unwrap();
     /// ```
-    pub fn delete_leaf(&mut self, index: usize) -> io::Result<()> {
+    pub fn delete_leaf(&mut self, index: usize) -> Result<()> {
         self.tree.delete(index)?;
         Ok(())
     }
@@ -338,7 +340,7 @@ impl RLN<'_> {
     /// rln.get_root(&mut buffer).unwrap();
     /// let (root, _) = bytes_le_to_fr(&buffer.into_inner());
     /// ```
-    pub fn get_root<W: Write>(&self, mut output_data: W) -> io::Result<()> {
+    pub fn get_root<W: Write>(&self, mut output_data: W) -> Result<()> {
         let root = self.tree.root();
         output_data.write_all(&fr_to_bytes_le(&root))?;
 
@@ -366,13 +368,13 @@ impl RLN<'_> {
     /// let (path_elements, read) = bytes_le_to_vec_fr(&buffer_inner);
     /// let (identity_path_index, _) = bytes_le_to_vec_u8(&buffer_inner[read..].to_vec());
     /// ```
-    pub fn get_proof<W: Write>(&self, index: usize, mut output_data: W) -> io::Result<()> {
+    pub fn get_proof<W: Write>(&self, index: usize, mut output_data: W) -> Result<()> {
         let merkle_proof = self.tree.proof(index).expect("proof should exist");
         let path_elements = merkle_proof.get_path_elements();
         let identity_path_index = merkle_proof.get_path_index();
 
-        output_data.write_all(&vec_fr_to_bytes_le(&path_elements))?;
-        output_data.write_all(&vec_u8_to_bytes_le(&identity_path_index))?;
+        output_data.write_all(&vec_fr_to_bytes_le(&path_elements)?)?;
+        output_data.write_all(&vec_u8_to_bytes_le(&identity_path_index)?)?;
 
         Ok(())
     }
@@ -406,11 +408,11 @@ impl RLN<'_> {
         &mut self,
         mut input_data: R,
         mut output_data: W,
-    ) -> io::Result<()> {
-        // We read input RLN witness and we deserialize it
+    ) -> Result<()> {
+        // We read input RLN witness and we serialize_compressed it
         let mut serialized: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut serialized)?;
-        let (rln_witness, _) = deserialize_witness(&serialized);
+        let (rln_witness, _) = deserialize_witness(&serialized)?;
 
         /*
         if self.witness_calculator.is_none() {
@@ -418,15 +420,10 @@ impl RLN<'_> {
         }
         */
 
-        let proof = generate_proof(
-            &mut self.witness_calculator,
-            self.proving_key.as_ref().unwrap(),
-            &rln_witness,
-        )
-        .unwrap();
+        let proof = generate_proof(self.witness_calculator, &self.proving_key, &rln_witness)?;
 
         // Note: we export a serialization of ark-groth16::Proof not semaphore::Proof
-        proof.serialize(&mut output_data).unwrap();
+        proof.serialize_compressed(&mut output_data)?;
 
         Ok(())
     }
@@ -466,22 +463,17 @@ impl RLN<'_> {
     ///
     /// assert!(verified);
     /// ```
-    pub fn verify<R: Read>(&self, mut input_data: R) -> io::Result<bool> {
+    pub fn verify<R: Read>(&self, mut input_data: R) -> Result<bool> {
         // Input data is serialized for Curve as:
         // serialized_proof (compressed, 4*32 bytes) || serialized_proof_values (6*32 bytes), i.e.
         // [ proof<128> | root<32> | epoch<32> | share_x<32> | share_y<32> | nullifier<32> | rln_identifier<32> ]
         let mut input_byte: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut input_byte)?;
-        let proof = ArkProof::deserialize(&mut Cursor::new(&input_byte[..128].to_vec())).unwrap();
+        let proof = ArkProof::deserialize_compressed(&mut Cursor::new(&input_byte[..128]))?;
 
-        let (proof_values, _) = deserialize_proof_values(&input_byte[128..].to_vec());
+        let (proof_values, _) = deserialize_proof_values(&input_byte[128..]);
 
-        let verified = verify_proof(
-            self.verification_key.as_ref().unwrap(),
-            &proof,
-            &proof_values,
-        )
-        .unwrap();
+        let verified = verify_proof(&self.verification_key, &proof, &proof_values)?;
 
         Ok(verified)
     }
@@ -510,8 +502,6 @@ impl RLN<'_> {
     /// // We generate a random signal
     /// let mut rng = rand::thread_rng();
     /// let signal: [u8; 32] = rng.gen();
-    /// let signal_len = u64::try_from(signal.len()).unwrap();
-    ///
     /// // We generate a random epoch
     /// let epoch = hash_to_field(b"test-epoch");
     ///
@@ -519,9 +509,9 @@ impl RLN<'_> {
     /// // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
     /// let mut serialized: Vec<u8> = Vec::new();
     /// serialized.append(&mut fr_to_bytes_le(&identity_secret_hash));
-    /// serialized.append(&mut identity_index.to_le_bytes().to_vec());
+    /// serialized.append(&mut normalize_usize(identity_index));
     /// serialized.append(&mut fr_to_bytes_le(&epoch));
-    /// serialized.append(&mut signal_len.to_le_bytes().to_vec());
+    /// serialized.append(&mut normalize_usize(signal_len).resize(8,0));
     /// serialized.append(&mut signal.to_vec());
     ///
     /// let mut input_buffer = Cursor::new(serialized);
@@ -537,23 +527,18 @@ impl RLN<'_> {
         &mut self,
         mut input_data: R,
         mut output_data: W,
-    ) -> io::Result<()> {
-        // We read input RLN witness and we deserialize it
+    ) -> Result<()> {
+        // We read input RLN witness and we serialize_compressed it
         let mut witness_byte: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut witness_byte)?;
-        let (rln_witness, _) = proof_inputs_to_rln_witness(&mut self.tree, &witness_byte);
+        let (rln_witness, _) = proof_inputs_to_rln_witness(&mut self.tree, &witness_byte)?;
         let proof_values = proof_values_from_witness(&rln_witness);
 
-        let proof = generate_proof(
-            self.witness_calculator,
-            self.proving_key.as_ref().unwrap(),
-            &rln_witness,
-        )
-        .unwrap();
+        let proof = generate_proof(self.witness_calculator, &self.proving_key, &rln_witness)?;
 
         // Note: we export a serialization of ark-groth16::Proof not semaphore::Proof
         // This proof is compressed, i.e. 128 bytes long
-        proof.serialize(&mut output_data).unwrap();
+        proof.serialize_compressed(&mut output_data)?;
         output_data.write_all(&serialize_proof_values(&proof_values))?;
 
         Ok(())
@@ -570,17 +555,15 @@ impl RLN<'_> {
         calculated_witness: Vec<BigInt>,
         rln_witness_vec: Vec<u8>,
         mut output_data: W,
-    ) -> io::Result<()> {
-        let (rln_witness, _) = deserialize_witness(&rln_witness_vec[..]);
+    ) -> Result<()> {
+        let (rln_witness, _) = deserialize_witness(&rln_witness_vec[..])?;
         let proof_values = proof_values_from_witness(&rln_witness);
 
-        let proof =
-            generate_proof_with_witness(calculated_witness, self.proving_key.as_ref().unwrap())
-                .unwrap();
+        let proof = generate_proof_with_witness(calculated_witness, &self.proving_key).unwrap();
 
         // Note: we export a serialization of ark-groth16::Proof not semaphore::Proof
         // This proof is compressed, i.e. 128 bytes long
-        proof.serialize(&mut output_data).unwrap();
+        proof.serialize_compressed(&mut output_data)?;
         output_data.write_all(&serialize_proof_values(&proof_values))?;
         Ok(())
     }
@@ -604,7 +587,7 @@ impl RLN<'_> {
     /// // We prepare input for verify_rln_proof API
     /// // input_data is [ proof<128> | share_y<32> | nullifier<32> | root<32> | epoch<32> | share_x<32> | rln_identifier<32> | signal_len<8> | signal<var> ]
     /// // that is [ proof_data || signal_len<8> | signal<var> ]
-    /// proof_data.append(&mut signal_len.to_le_bytes().to_vec());
+    /// proof_data.append(&mut normalize_usize(signal_len));
     /// proof_data.append(&mut signal.to_vec());
     ///
     /// let mut input_buffer = Cursor::new(proof_data);
@@ -612,27 +595,22 @@ impl RLN<'_> {
     ///
     /// assert!(verified);
     /// ```
-    pub fn verify_rln_proof<R: Read>(&self, mut input_data: R) -> io::Result<bool> {
+    pub fn verify_rln_proof<R: Read>(&self, mut input_data: R) -> Result<bool> {
         let mut serialized: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut serialized)?;
         let mut all_read = 0;
-        let proof = ArkProof::deserialize(&mut Cursor::new(&serialized[..128].to_vec())).unwrap();
+        let proof =
+            ArkProof::deserialize_compressed(&mut Cursor::new(&serialized[..128].to_vec()))?;
         all_read += 128;
-        let (proof_values, read) = deserialize_proof_values(&serialized[all_read..].to_vec());
+        let (proof_values, read) = deserialize_proof_values(&serialized[all_read..]);
         all_read += read;
 
-        let signal_len =
-            u64::from_le_bytes(serialized[all_read..all_read + 8].try_into().unwrap()) as usize;
+        let signal_len = usize::from_le_bytes(serialized[all_read..all_read + 8].try_into()?);
         all_read += 8;
 
         let signal: Vec<u8> = serialized[all_read..all_read + signal_len].to_vec();
 
-        let verified = verify_proof(
-            self.verification_key.as_ref().unwrap(),
-            &proof,
-            &proof_values,
-        )
-        .unwrap();
+        let verified = verify_proof(&self.verification_key, &proof, &proof_values)?;
 
         // Consistency checks to counter proof tampering
         let x = hash_to_field(&signal);
@@ -693,31 +671,22 @@ impl RLN<'_> {
     ///
     /// assert!(verified);
     /// ```
-    pub fn verify_with_roots<R: Read>(
-        &self,
-        mut input_data: R,
-        mut roots_data: R,
-    ) -> io::Result<bool> {
+    pub fn verify_with_roots<R: Read>(&self, mut input_data: R, mut roots_data: R) -> Result<bool> {
         let mut serialized: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut serialized)?;
         let mut all_read = 0;
-        let proof = ArkProof::deserialize(&mut Cursor::new(&serialized[..128].to_vec())).unwrap();
+        let proof =
+            ArkProof::deserialize_compressed(&mut Cursor::new(&serialized[..128].to_vec()))?;
         all_read += 128;
-        let (proof_values, read) = deserialize_proof_values(&serialized[all_read..].to_vec());
+        let (proof_values, read) = deserialize_proof_values(&serialized[all_read..]);
         all_read += read;
 
-        let signal_len =
-            u64::from_le_bytes(serialized[all_read..all_read + 8].try_into().unwrap()) as usize;
+        let signal_len = usize::from_le_bytes(serialized[all_read..all_read + 8].try_into()?);
         all_read += 8;
 
         let signal: Vec<u8> = serialized[all_read..all_read + signal_len].to_vec();
 
-        let verified = verify_proof(
-            self.verification_key.as_ref().unwrap(),
-            &proof,
-            &proof_values,
-        )
-        .unwrap();
+        let verified = verify_proof(&self.verification_key, &proof, &proof_values)?;
 
         // First consistency checks to counter proof tampering
         let x = hash_to_field(&signal);
@@ -726,7 +695,7 @@ impl RLN<'_> {
             && (proof_values.rln_identifier == hash_to_field(RLN_IDENTIFIER));
 
         // We skip root validation if proof is already invalid
-        if partial_result == false {
+        if !partial_result {
             return Ok(partial_result);
         }
 
@@ -749,14 +718,13 @@ impl RLN<'_> {
         }
 
         // We validate the root
-        let roots_verified: bool;
-        if roots.is_empty() {
+        let roots_verified: bool = if roots.is_empty() {
             // If no root is passed in roots_buffer, we skip proof's root check
-            roots_verified = true;
+            true
         } else {
             // Otherwise we check if proof's root is contained in the passed buffer
-            roots_verified = roots.contains(&proof_values.root);
-        }
+            roots.contains(&proof_values.root)
+        };
 
         // We combine all checks
         Ok(partial_result && roots_verified)
@@ -781,10 +749,10 @@ impl RLN<'_> {
     /// let mut buffer = Cursor::new(Vec::<u8>::new());
     /// rln.key_gen(&mut buffer).unwrap();
     ///
-    /// // We deserialize the keygen output
+    /// // We serialize_compressed the keygen output
     /// let (identity_secret_hash, id_commitment) = deserialize_identity_pair(buffer.into_inner());
     /// ```
-    pub fn key_gen<W: Write>(&self, mut output_data: W) -> io::Result<()> {
+    pub fn key_gen<W: Write>(&self, mut output_data: W) -> Result<()> {
         let (identity_secret_hash, id_commitment) = keygen();
         output_data.write_all(&fr_to_bytes_le(&identity_secret_hash))?;
         output_data.write_all(&fr_to_bytes_le(&id_commitment))?;
@@ -811,10 +779,10 @@ impl RLN<'_> {
     /// let mut buffer = Cursor::new(Vec::<u8>::new());
     /// rln.extended_key_gen(&mut buffer).unwrap();
     ///
-    /// // We deserialize the keygen output
+    /// // We serialize_compressed the keygen output
     /// let (identity_trapdoor, identity_nullifier, identity_secret_hash, id_commitment) = deserialize_identity_tuple(buffer.into_inner());
     /// ```
-    pub fn extended_key_gen<W: Write>(&self, mut output_data: W) -> io::Result<()> {
+    pub fn extended_key_gen<W: Write>(&self, mut output_data: W) -> Result<()> {
         let (identity_trapdoor, identity_nullifier, identity_secret_hash, id_commitment) =
             extended_keygen();
         output_data.write_all(&fr_to_bytes_le(&identity_trapdoor))?;
@@ -846,14 +814,14 @@ impl RLN<'_> {
     /// rln.seeded_key_gen(&mut input_buffer, &mut output_buffer)
     ///     .unwrap();
     ///
-    /// // We deserialize the keygen output
+    /// // We serialize_compressed the keygen output
     /// let (identity_secret_hash, id_commitment) = deserialize_identity_pair(output_buffer.into_inner());
     /// ```
     pub fn seeded_key_gen<R: Read, W: Write>(
         &self,
         mut input_data: R,
         mut output_data: W,
-    ) -> io::Result<()> {
+    ) -> Result<()> {
         let mut serialized: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut serialized)?;
 
@@ -889,14 +857,14 @@ impl RLN<'_> {
     /// rln.seeded_key_gen(&mut input_buffer, &mut output_buffer)
     ///     .unwrap();
     ///
-    /// // We deserialize the keygen output
+    /// // We serialize_compressed the keygen output
     /// let (identity_trapdoor, identity_nullifier, identity_secret_hash, id_commitment) = deserialize_identity_tuple(buffer.into_inner());
     /// ```
     pub fn seeded_extended_key_gen<R: Read, W: Write>(
         &self,
         mut input_data: R,
         mut output_data: W,
-    ) -> io::Result<()> {
+    ) -> Result<()> {
         let mut serialized: Vec<u8> = Vec::new();
         input_data.read_to_end(&mut serialized)?;
 
@@ -947,21 +915,21 @@ impl RLN<'_> {
         mut input_proof_data_1: R,
         mut input_proof_data_2: R,
         mut output_data: W,
-    ) -> io::Result<()> {
-        // We deserialize the two proofs and we get the corresponding RLNProofValues objects
+    ) -> Result<()> {
+        // We serialize_compressed the two proofs and we get the corresponding RLNProofValues objects
         let mut serialized: Vec<u8> = Vec::new();
         input_proof_data_1.read_to_end(&mut serialized)?;
         // We skip deserialization of the zk-proof at the beginning
-        let (proof_values_1, _) = deserialize_proof_values(&serialized[128..].to_vec());
+        let (proof_values_1, _) = deserialize_proof_values(&serialized[128..]);
         let external_nullifier_1 =
-            poseidon_hash(&[proof_values_1.epoch, proof_values_1.rln_identifier]);
+            utils_poseidon_hash(&[proof_values_1.epoch, proof_values_1.rln_identifier]);
 
         let mut serialized: Vec<u8> = Vec::new();
         input_proof_data_2.read_to_end(&mut serialized)?;
         // We skip deserialization of the zk-proof at the beginning
-        let (proof_values_2, _) = deserialize_proof_values(&serialized[128..].to_vec());
+        let (proof_values_2, _) = deserialize_proof_values(&serialized[128..]);
         let external_nullifier_2 =
-            poseidon_hash(&[proof_values_2.epoch, proof_values_2.rln_identifier]);
+            utils_poseidon_hash(&[proof_values_2.epoch, proof_values_2.rln_identifier]);
 
         // We continue only if the proof values are for the same epoch
         // The idea is that proof values that go as input to this function are verified first (with zk-proof verify), hence ensuring validity of epoch and other fields.
@@ -977,8 +945,7 @@ impl RLN<'_> {
                 compute_id_secret(share1, share2, external_nullifier_1);
 
             // If an identity secret hash is recovered, we write it to output_data, otherwise nothing will be written.
-            if recovered_identity_secret_hash.is_ok() {
-                let identity_secret_hash = recovered_identity_secret_hash.unwrap();
+            if let Ok(identity_secret_hash) = recovered_identity_secret_hash {
                 output_data.write_all(&fr_to_bytes_le(&identity_secret_hash))?;
             }
         }
@@ -986,49 +953,17 @@ impl RLN<'_> {
         Ok(())
     }
 
-    /// Hashes an input signal to an element in the working prime field.
-    ///
-    /// The result is computed as the Keccak256 of the input signal modulo the prime field characteristic.
-    ///
-    /// Input values are:
-    /// - `input_data`: a reader for the byte vector containing the input signal.
-    ///
-    /// Output values are:
-    /// - `output_data`: a writer receiving the serialization of the resulting field element (serialization done with [`rln::utils::fr_to_bytes_le`](crate::utils::fr_to_bytes_le))
-    ///
-    /// Example
-    /// ```
-    /// let signal: &[u8] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
-    ///
-    /// let mut input_buffer = Cursor::new(&signal);
-    /// let mut output_buffer = Cursor::new(Vec::<u8>::new());
-    /// rln.hash(&mut input_buffer, &mut output_buffer)
-    ///     .unwrap();
-    ///
-    /// // We deserialize the keygen output
-    /// let field_element = deserialize_field_element(output_buffer.into_inner());
-    /// ```
-    pub fn hash<R: Read, W: Write>(&self, mut input_data: R, mut output_data: W) -> io::Result<()> {
-        let mut serialized: Vec<u8> = Vec::new();
-        input_data.read_to_end(&mut serialized)?;
-
-        let hash = hash_to_field(&serialized);
-        output_data.write_all(&fr_to_bytes_le(&hash))?;
-
-        Ok(())
-    }
-
     /// Returns the serialization of a [`RLNWitnessInput`](crate::protocol::RLNWitnessInput) populated from the identity secret, the Merkle tree index, the epoch and signal.
     ///
     /// Input values are:
     /// - `input_data`: a reader for the serialization of `[ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]`
     ///
     /// The function returns the corresponding [`RLNWitnessInput`](crate::protocol::RLNWitnessInput) object serialized using [`rln::protocol::serialize_witness`](crate::protocol::serialize_witness)).
-    pub fn get_serialized_rln_witness<R: Read>(&mut self, mut input_data: R) -> Vec<u8> {
-        // We read input RLN witness and we deserialize it
+    pub fn get_serialized_rln_witness<R: Read>(&mut self, mut input_data: R) -> Result<Vec<u8>> {
+        // We read input RLN witness and we serialize_compressed it
         let mut witness_byte: Vec<u8> = Vec::new();
-        input_data.read_to_end(&mut witness_byte).unwrap();
-        let (rln_witness, _) = proof_inputs_to_rln_witness(&mut self.tree, &witness_byte);
+        input_data.read_to_end(&mut witness_byte)?;
+        let (rln_witness, _) = proof_inputs_to_rln_witness(&mut self.tree, &witness_byte)?;
 
         serialize_witness(&rln_witness)
     }
@@ -1039,12 +974,9 @@ impl RLN<'_> {
     /// - `serialized_witness`: the byte serialization of a [`RLNWitnessInput`](crate::protocol::RLNWitnessInput) object (serialization done with  [`rln::protocol::serialize_witness`](crate::protocol::serialize_witness)).
     ///
     /// The function returns the corresponding JSON encoding of the input [`RLNWitnessInput`](crate::protocol::RLNWitnessInput) object.
-    pub fn get_rln_witness_json(
-        &mut self,
-        serialized_witness: &[u8],
-    ) -> io::Result<serde_json::Value> {
-        let (rln_witness, _) = deserialize_witness(serialized_witness);
-        Ok(get_json_inputs(&rln_witness))
+    pub fn get_rln_witness_json(&mut self, serialized_witness: &[u8]) -> Result<serde_json::Value> {
+        let (rln_witness, _) = deserialize_witness(serialized_witness)?;
+        get_json_inputs(&rln_witness)
     }
 }
 
@@ -1053,15 +985,83 @@ impl Default for RLN<'_> {
     fn default() -> Self {
         let tree_height = TEST_TREE_HEIGHT;
         let buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        Self::new(tree_height, buffer)
+        Self::new(tree_height, buffer).unwrap()
     }
 }
 
+/// Hashes an input signal to an element in the working prime field.
+///
+/// The result is computed as the Keccak256 of the input signal modulo the prime field characteristic.
+///
+/// Input values are:
+/// - `input_data`: a reader for the byte vector containing the input signal.
+///
+/// Output values are:
+/// - `output_data`: a writer receiving the serialization of the resulting field element (serialization done with [`rln::utils::fr_to_bytes_le`](crate::utils::fr_to_bytes_le))
+///
+/// Example
+/// ```
+/// let signal: &[u8] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+///
+/// let mut input_buffer = Cursor::new(&signal);
+/// let mut output_buffer = Cursor::new(Vec::<u8>::new());
+/// hash(&mut input_buffer, &mut output_buffer)
+///     .unwrap();
+///
+/// // We serialize_compressed the keygen output
+/// let field_element = deserialize_field_element(output_buffer.into_inner());
+/// ```
+pub fn hash<R: Read, W: Write>(mut input_data: R, mut output_data: W) -> Result<()> {
+    let mut serialized: Vec<u8> = Vec::new();
+    input_data.read_to_end(&mut serialized)?;
+
+    let hash = hash_to_field(&serialized);
+    output_data.write_all(&fr_to_bytes_le(&hash))?;
+
+    Ok(())
+}
+
+/// Hashes a set of elements to a single element in the working prime field, using Poseidon.
+///
+/// The result is computed as the Poseidon Hash of the input signal.
+///
+/// Input values are:
+/// - `input_data`: a reader for the byte vector containing the input signal.
+///
+/// Output values are:
+/// - `output_data`: a writer receiving the serialization of the resulting field element (serialization done with [`rln::utils::fr_to_bytes_le`](crate::utils::fr_to_bytes_le))
+///
+/// Example
+/// ```
+/// let data = vec![hash_to_field(b"foo")];
+/// let signal = vec_fr_to_bytes_le(&data);
+///
+/// let mut input_buffer = Cursor::new(&signal);
+/// let mut output_buffer = Cursor::new(Vec::<u8>::new());
+/// poseidon_hash(&mut input_buffer, &mut output_buffer)
+///     .unwrap();
+///
+/// // We serialize_compressed the hash output
+/// let hash_result = deserialize_field_element(output_buffer.into_inner());
+/// ```
+pub fn poseidon_hash<R: Read, W: Write>(mut input_data: R, mut output_data: W) -> Result<()> {
+    let mut serialized: Vec<u8> = Vec::new();
+    input_data.read_to_end(&mut serialized)?;
+
+    let (inputs, _) = bytes_le_to_vec_fr(&serialized)?;
+    let hash = utils_poseidon_hash(inputs.as_ref());
+    output_data.write_all(&fr_to_bytes_le(&hash))?;
+
+    Ok(())
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
     use ark_std::{rand::thread_rng, UniformRand};
     use rand::Rng;
+    use utils::ZerokitMerkleTree;
+    // use rkyv::Deserialize;
 
     #[test]
     // We test merkle batch Merkle tree additions
@@ -1078,7 +1078,7 @@ mod test {
 
         // We create a new tree
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // We first add leaves one by one specifying the index
         for (i, leaf) in leaves.iter().enumerate() {
@@ -1117,7 +1117,7 @@ mod test {
         rln.set_tree(tree_height).unwrap();
 
         // We add leaves in a batch into the tree
-        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves));
+        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves).unwrap());
         rln.init_tree_with_leaves(&mut buffer).unwrap();
 
         // We check if number of leaves set is consistent
@@ -1173,10 +1173,10 @@ mod test {
 
         // We create a new tree
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // We add leaves in a batch into the tree
-        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves));
+        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves).unwrap());
         rln.init_tree_with_leaves(&mut buffer).unwrap();
 
         // We check if number of leaves set is consistent
@@ -1190,11 +1190,11 @@ mod test {
         // `init_tree_with_leaves` resets the tree to the height it was initialized with, using `set_tree`
 
         // We add leaves in a batch starting from index 0..set_index
-        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves[0..set_index]));
+        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves[0..set_index]).unwrap());
         rln.init_tree_with_leaves(&mut buffer).unwrap();
 
         // We add the remaining n leaves in a batch starting from index m
-        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves[set_index..]));
+        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves[set_index..]).unwrap());
         rln.set_leaves_from(set_index, &mut buffer).unwrap();
 
         // We check if number of leaves set is consistent
@@ -1227,6 +1227,7 @@ mod test {
         assert_eq!(root_batch_with_init, root_single_additions);
     }
 
+    #[allow(unused_must_use)]
     #[test]
     // This test checks if `set_leaves_from` throws an error when the index is out of bounds
     fn test_set_leaves_bad_index() {
@@ -1243,7 +1244,7 @@ mod test {
 
         // We create a new tree
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // Get root of empty tree
         let mut buffer = Cursor::new(Vec::<u8>::new());
@@ -1251,7 +1252,7 @@ mod test {
         let (root_empty, _) = bytes_le_to_fr(&buffer.into_inner());
 
         // We add leaves in a batch into the tree
-        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves));
+        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves).unwrap());
         rln.set_leaves_from(bad_index, &mut buffer)
             .expect_err("Should throw an error");
 
@@ -1272,25 +1273,21 @@ mod test {
         let tree_height = TEST_TREE_HEIGHT;
 
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // Note: we only test Groth16 proof generation, so we ignore setting the tree in the RLN object
         let rln_witness = random_rln_witness(tree_height);
         let proof_values = proof_values_from_witness(&rln_witness);
 
         // We compute a Groth16 proof
-        let mut input_buffer = Cursor::new(serialize_witness(&rln_witness));
+        let mut input_buffer = Cursor::new(serialize_witness(&rln_witness).unwrap());
         let mut output_buffer = Cursor::new(Vec::<u8>::new());
         rln.prove(&mut input_buffer, &mut output_buffer).unwrap();
         let serialized_proof = output_buffer.into_inner();
 
         // Before checking public verify API, we check that the (deserialized) proof generated by prove is actually valid
-        let proof = ArkProof::deserialize(&mut Cursor::new(&serialized_proof)).unwrap();
-        let verified = verify_proof(
-            &rln.verification_key.as_ref().unwrap(),
-            &proof,
-            &proof_values,
-        );
+        let proof = ArkProof::deserialize_compressed(&mut Cursor::new(&serialized_proof)).unwrap();
+        let verified = verify_proof(&rln.verification_key, &proof, &proof_values);
         assert!(verified.unwrap());
 
         // We prepare the input to prove API, consisting of serialized_proof (compressed, 4*32 bytes) || serialized_proof_values (6*32 bytes)
@@ -1320,24 +1317,23 @@ mod test {
 
         // We create a new RLN instance
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // We add leaves in a batch into the tree
-        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves));
+        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves).unwrap());
         rln.init_tree_with_leaves(&mut buffer).unwrap();
 
         // Generate identity pair
         let (identity_secret_hash, id_commitment) = keygen();
 
         // We set as leaf id_commitment after storing its index
-        let identity_index = u64::try_from(rln.tree.leaves_set()).unwrap();
+        let identity_index = rln.tree.leaves_set();
         let mut buffer = Cursor::new(fr_to_bytes_le(&id_commitment));
         rln.set_next_leaf(&mut buffer).unwrap();
 
         // We generate a random signal
         let mut rng = rand::thread_rng();
         let signal: [u8; 32] = rng.gen();
-        let signal_len = u64::try_from(signal.len()).unwrap();
 
         // We generate a random epoch
         let epoch = hash_to_field(b"test-epoch");
@@ -1346,9 +1342,9 @@ mod test {
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         let mut serialized: Vec<u8> = Vec::new();
         serialized.append(&mut fr_to_bytes_le(&identity_secret_hash));
-        serialized.append(&mut identity_index.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(identity_index));
         serialized.append(&mut fr_to_bytes_le(&epoch));
-        serialized.append(&mut signal_len.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(signal.len()));
         serialized.append(&mut signal.to_vec());
 
         let mut input_buffer = Cursor::new(serialized);
@@ -1362,7 +1358,7 @@ mod test {
         // We prepare input for verify_rln_proof API
         // input_data is [ proof<128> | share_y<32> | nullifier<32> | root<32> | epoch<32> | share_x<32> | rln_identifier<32> | signal_len<8> | signal<var> ]
         // that is [ proof_data || signal_len<8> | signal<var> ]
-        proof_data.append(&mut signal_len.to_le_bytes().to_vec());
+        proof_data.append(&mut normalize_usize(signal.len()));
         proof_data.append(&mut signal.to_vec());
 
         let mut input_buffer = Cursor::new(proof_data);
@@ -1385,24 +1381,23 @@ mod test {
 
         // We create a new RLN instance
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // We add leaves in a batch into the tree
-        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves));
+        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves).unwrap());
         rln.init_tree_with_leaves(&mut buffer).unwrap();
 
         // Generate identity pair
         let (identity_secret_hash, id_commitment) = keygen();
 
         // We set as leaf id_commitment after storing its index
-        let identity_index = u64::try_from(rln.tree.leaves_set()).unwrap();
+        let identity_index = rln.tree.leaves_set();
         let mut buffer = Cursor::new(fr_to_bytes_le(&id_commitment));
         rln.set_next_leaf(&mut buffer).unwrap();
 
         // We generate a random signal
         let mut rng = rand::thread_rng();
         let signal: [u8; 32] = rng.gen();
-        let signal_len = u64::try_from(signal.len()).unwrap();
 
         // We generate a random epoch
         let epoch = hash_to_field(b"test-epoch");
@@ -1411,22 +1406,23 @@ mod test {
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         let mut serialized: Vec<u8> = Vec::new();
         serialized.append(&mut fr_to_bytes_le(&identity_secret_hash));
-        serialized.append(&mut identity_index.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(identity_index));
         serialized.append(&mut fr_to_bytes_le(&epoch));
-        serialized.append(&mut signal_len.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(signal.len()));
         serialized.append(&mut signal.to_vec());
 
         let mut input_buffer = Cursor::new(serialized);
 
-        // We read input RLN witness and we deserialize it
+        // We read input RLN witness and we serialize_compressed it
         let mut witness_byte: Vec<u8> = Vec::new();
         input_buffer.read_to_end(&mut witness_byte).unwrap();
-        let (rln_witness, _) = proof_inputs_to_rln_witness(&mut rln.tree, &witness_byte);
+        let (rln_witness, _) = proof_inputs_to_rln_witness(&mut rln.tree, &witness_byte).unwrap();
 
-        let serialized_witness = serialize_witness(&rln_witness);
+        let serialized_witness = serialize_witness(&rln_witness).unwrap();
 
         // Calculate witness outside zerokit (simulating what JS is doing)
         let inputs = inputs_for_witness_calculation(&rln_witness)
+            .unwrap()
             .into_iter()
             .map(|(name, values)| (name.to_string(), values));
         let calculated_witness = rln
@@ -1439,7 +1435,7 @@ mod test {
 
         let calculated_witness_vec: Vec<BigInt> = calculated_witness
             .into_iter()
-            .map(|v| to_bigint(&v))
+            .map(|v| to_bigint(&v).unwrap())
             .collect();
 
         // Generating the proof
@@ -1457,7 +1453,7 @@ mod test {
         // We prepare input for verify_rln_proof API
         // input_data is [ proof<128> | share_y<32> | nullifier<32> | root<32> | epoch<32> | share_x<32> | rln_identifier<32> | signal_len<8> | signal<var> ]
         // that is [ proof_data || signal_len<8> | signal<var> ]
-        proof_data.append(&mut signal_len.to_le_bytes().to_vec());
+        proof_data.append(&mut normalize_usize(signal.len()));
         proof_data.append(&mut signal.to_vec());
 
         let mut input_buffer = Cursor::new(proof_data);
@@ -1481,24 +1477,23 @@ mod test {
 
         // We create a new RLN instance
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // We add leaves in a batch into the tree
-        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves));
+        let mut buffer = Cursor::new(vec_fr_to_bytes_le(&leaves).unwrap());
         rln.init_tree_with_leaves(&mut buffer).unwrap();
 
         // Generate identity pair
         let (identity_secret_hash, id_commitment) = keygen();
 
         // We set as leaf id_commitment after storing its index
-        let identity_index = u64::try_from(rln.tree.leaves_set()).unwrap();
+        let identity_index = rln.tree.leaves_set();
         let mut buffer = Cursor::new(fr_to_bytes_le(&id_commitment));
         rln.set_next_leaf(&mut buffer).unwrap();
 
         // We generate a random signal
         let mut rng = rand::thread_rng();
         let signal: [u8; 32] = rng.gen();
-        let signal_len = u64::try_from(signal.len()).unwrap();
 
         // We generate a random epoch
         let epoch = hash_to_field(b"test-epoch");
@@ -1507,9 +1502,9 @@ mod test {
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         let mut serialized: Vec<u8> = Vec::new();
         serialized.append(&mut fr_to_bytes_le(&identity_secret_hash));
-        serialized.append(&mut identity_index.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(identity_index));
         serialized.append(&mut fr_to_bytes_le(&epoch));
-        serialized.append(&mut signal_len.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(signal.len()));
         serialized.append(&mut signal.to_vec());
 
         let mut input_buffer = Cursor::new(serialized);
@@ -1523,7 +1518,7 @@ mod test {
         // We prepare input for verify_rln_proof API
         // input_data is [ proof<128> | share_y<32> | nullifier<32> | root<32> | epoch<32> | share_x<32> | rln_identifier<32> | signal_len<8> | signal<var> ]
         // that is [ proof_data || signal_len<8> | signal<var> ]
-        proof_data.append(&mut signal_len.to_le_bytes().to_vec());
+        proof_data.append(&mut normalize_usize(signal.len()));
         proof_data.append(&mut signal.to_vec());
         let input_buffer = Cursor::new(proof_data);
 
@@ -1568,23 +1563,21 @@ mod test {
 
         // We create a new RLN instance
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // Generate identity pair
         let (identity_secret_hash, id_commitment) = keygen();
 
         // We set as leaf id_commitment after storing its index
-        let identity_index = u64::try_from(rln.tree.leaves_set()).unwrap();
+        let identity_index = rln.tree.leaves_set();
         let mut buffer = Cursor::new(fr_to_bytes_le(&id_commitment));
         rln.set_next_leaf(&mut buffer).unwrap();
 
         // We generate two random signals
         let mut rng = rand::thread_rng();
         let signal1: [u8; 32] = rng.gen();
-        let signal1_len = u64::try_from(signal1.len()).unwrap();
 
         let signal2: [u8; 32] = rng.gen();
-        let signal2_len = u64::try_from(signal2.len()).unwrap();
 
         // We generate a random epoch
         let epoch = hash_to_field(b"test-epoch");
@@ -1595,18 +1588,18 @@ mod test {
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         let mut serialized1: Vec<u8> = Vec::new();
         serialized1.append(&mut fr_to_bytes_le(&identity_secret_hash));
-        serialized1.append(&mut identity_index.to_le_bytes().to_vec());
+        serialized1.append(&mut normalize_usize(identity_index));
         serialized1.append(&mut fr_to_bytes_le(&epoch));
 
         // The first part is the same for both proof input, so we clone
         let mut serialized2 = serialized1.clone();
 
         // We attach the first signal to the first proof input
-        serialized1.append(&mut signal1_len.to_le_bytes().to_vec());
+        serialized1.append(&mut normalize_usize(signal1.len()));
         serialized1.append(&mut signal1.to_vec());
 
         // We attach the second signal to the first proof input
-        serialized2.append(&mut signal2_len.to_le_bytes().to_vec());
+        serialized2.append(&mut normalize_usize(signal2.len()));
         serialized2.append(&mut signal2.to_vec());
 
         // We generate the first proof
@@ -1648,21 +1641,20 @@ mod test {
         let (identity_secret_hash_new, id_commitment_new) = keygen();
 
         // We add it to the tree
-        let identity_index_new = u64::try_from(rln.tree.leaves_set()).unwrap();
+        let identity_index_new = rln.tree.leaves_set();
         let mut buffer = Cursor::new(fr_to_bytes_le(&id_commitment_new));
         rln.set_next_leaf(&mut buffer).unwrap();
 
         // We generate a random signals
         let signal3: [u8; 32] = rng.gen();
-        let signal3_len = u64::try_from(signal3.len()).unwrap();
 
         // We prepare proof input. Note that epoch is the same as before
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         let mut serialized3: Vec<u8> = Vec::new();
         serialized3.append(&mut fr_to_bytes_le(&identity_secret_hash_new));
-        serialized3.append(&mut identity_index_new.to_le_bytes().to_vec());
+        serialized3.append(&mut normalize_usize(identity_index_new));
         serialized3.append(&mut fr_to_bytes_le(&epoch));
-        serialized3.append(&mut signal3_len.to_le_bytes().to_vec());
+        serialized3.append(&mut normalize_usize(signal3.len()));
         serialized3.append(&mut signal3.to_vec());
 
         // We generate the proof

rln/src/utils.rs

@@ -2,22 +2,25 @@
 
 use crate::circuit::Fr;
 use ark_ff::PrimeField;
+use color_eyre::{Report, Result};
 use num_bigint::{BigInt, BigUint};
 use num_traits::Num;
 use std::iter::Extend;
 
-pub fn to_bigint(el: &Fr) -> BigInt {
-    let res: BigUint = (*el).try_into().unwrap();
-    res.try_into().unwrap()
+pub fn to_bigint(el: &Fr) -> Result<BigInt> {
+    let res: BigUint = (*el).try_into()?;
+    Ok(res.into())
 }
 
 pub fn fr_byte_size() -> usize {
-    let mbs = <Fr as PrimeField>::size_in_bits();
-    (mbs + 64 - (mbs % 64)) / 8
+    let mbs = <Fr as PrimeField>::MODULUS_BIT_SIZE;
+    ((mbs + 64 - (mbs % 64)) / 8) as usize
 }
 
-pub fn str_to_fr(input: &str, radix: u32) -> Fr {
-    assert!((radix == 10) || (radix == 16));
+pub fn str_to_fr(input: &str, radix: u32) -> Result<Fr> {
+    if !(radix == 10 || radix == 16) {
+        return Err(Report::msg("wrong radix"));
+    }
 
     // We remove any quote present and we trim
     let single_quote: char = '\"';
@@ -25,16 +28,10 @@ pub fn str_to_fr(input: &str, radix: u32) -> Fr {
     input_clean = input_clean.trim().to_string();
 
     if radix == 10 {
-        BigUint::from_str_radix(&input_clean, radix)
-            .unwrap()
-            .try_into()
-            .unwrap()
+        Ok(BigUint::from_str_radix(&input_clean, radix)?.try_into()?)
     } else {
         input_clean = input_clean.replace("0x", "");
-        BigUint::from_str_radix(&input_clean, radix)
-            .unwrap()
-            .try_into()
-            .unwrap()
+        Ok(BigUint::from_str_radix(&input_clean, radix)?.try_into()?)
     }
 }
 
@@ -75,99 +72,111 @@ pub fn fr_to_bytes_be(input: &Fr) -> Vec<u8> {
     res
 }
 
-pub fn vec_fr_to_bytes_le(input: &[Fr]) -> Vec<u8> {
+pub fn vec_fr_to_bytes_le(input: &[Fr]) -> Result<Vec<u8>> {
     let mut bytes: Vec<u8> = Vec::new();
     //We store the vector length
-    bytes.extend(u64::try_from(input.len()).unwrap().to_le_bytes().to_vec());
+    bytes.extend(input.len().to_le_bytes().to_vec());
+
     // We store each element
     input.iter().for_each(|el| bytes.extend(fr_to_bytes_le(el)));
 
-    bytes
+    Ok(bytes)
 }
 
-pub fn vec_fr_to_bytes_be(input: &[Fr]) -> Vec<u8> {
+pub fn vec_fr_to_bytes_be(input: &[Fr]) -> Result<Vec<u8>> {
     let mut bytes: Vec<u8> = Vec::new();
     //We store the vector length
-    bytes.extend(u64::try_from(input.len()).unwrap().to_be_bytes().to_vec());
+    bytes.extend(input.len().to_be_bytes().to_vec());
+
     // We store each element
     input.iter().for_each(|el| bytes.extend(fr_to_bytes_be(el)));
 
-    bytes
+    Ok(bytes)
 }
 
-pub fn vec_u8_to_bytes_le(input: &[u8]) -> Vec<u8> {
+pub fn vec_u8_to_bytes_le(input: &[u8]) -> Result<Vec<u8>> {
     let mut bytes: Vec<u8> = Vec::new();
     //We store the vector length
-    bytes.extend(u64::try_from(input.len()).unwrap().to_le_bytes().to_vec());
+    bytes.extend(input.len().to_le_bytes().to_vec());
+
     bytes.extend(input);
-    bytes
+
+    Ok(bytes)
 }
 
-pub fn vec_u8_to_bytes_be(input: Vec<u8>) -> Vec<u8> {
+pub fn vec_u8_to_bytes_be(input: Vec<u8>) -> Result<Vec<u8>> {
     let mut bytes: Vec<u8> = Vec::new();
     //We store the vector length
-    bytes.extend(u64::try_from(input.len()).unwrap().to_be_bytes().to_vec());
+    bytes.extend(input.len().to_be_bytes().to_vec());
+
     bytes.extend(input);
-    bytes
+
+    Ok(bytes)
 }
 
-pub fn bytes_le_to_vec_u8(input: &[u8]) -> (Vec<u8>, usize) {
+pub fn bytes_le_to_vec_u8(input: &[u8]) -> Result<(Vec<u8>, usize)> {
     let mut read: usize = 0;
 
-    let len = u64::from_le_bytes(input[0..8].try_into().unwrap()) as usize;
+    let len = usize::from_le_bytes(input[0..8].try_into()?);
     read += 8;
 
     let res = input[8..8 + len].to_vec();
     read += res.len();
 
-    (res, read)
+    Ok((res, read))
 }
 
-pub fn bytes_be_to_vec_u8(input: &[u8]) -> (Vec<u8>, usize) {
+pub fn bytes_be_to_vec_u8(input: &[u8]) -> Result<(Vec<u8>, usize)> {
     let mut read: usize = 0;
 
-    let len = u64::from_be_bytes(input[0..8].try_into().unwrap()) as usize;
+    let len = usize::from_be_bytes(input[0..8].try_into()?);
     read += 8;
 
     let res = input[8..8 + len].to_vec();
 
     read += res.len();
 
-    (res, read)
+    Ok((res, read))
 }
 
-pub fn bytes_le_to_vec_fr(input: &[u8]) -> (Vec<Fr>, usize) {
+pub fn bytes_le_to_vec_fr(input: &[u8]) -> Result<(Vec<Fr>, usize)> {
     let mut read: usize = 0;
     let mut res: Vec<Fr> = Vec::new();
 
-    let len = u64::from_le_bytes(input[0..8].try_into().unwrap()) as usize;
+    let len = usize::from_le_bytes(input[0..8].try_into()?);
     read += 8;
 
     let el_size = fr_byte_size();
     for i in 0..len {
-        let (curr_el, _) = bytes_le_to_fr(&input[8 + el_size * i..8 + el_size * (i + 1)].to_vec());
+        let (curr_el, _) = bytes_le_to_fr(&input[8 + el_size * i..8 + el_size * (i + 1)]);
         res.push(curr_el);
         read += el_size;
     }
 
-    (res, read)
+    Ok((res, read))
 }
 
-pub fn bytes_be_to_vec_fr(input: &[u8]) -> (Vec<Fr>, usize) {
+pub fn bytes_be_to_vec_fr(input: &[u8]) -> Result<(Vec<Fr>, usize)> {
     let mut read: usize = 0;
     let mut res: Vec<Fr> = Vec::new();
 
-    let len = u64::from_be_bytes(input[0..8].try_into().unwrap()) as usize;
+    let len = usize::from_be_bytes(input[0..8].try_into()?);
     read += 8;
 
     let el_size = fr_byte_size();
     for i in 0..len {
-        let (curr_el, _) = bytes_be_to_fr(&input[8 + el_size * i..8 + el_size * (i + 1)].to_vec());
+        let (curr_el, _) = bytes_be_to_fr(&input[8 + el_size * i..8 + el_size * (i + 1)]);
         res.push(curr_el);
         read += el_size;
     }
 
-    (res, read)
+    Ok((res, read))
+}
+
+pub fn normalize_usize(input: usize) -> Vec<u8> {
+    let mut normalized_usize = input.to_le_bytes().to_vec();
+    normalized_usize.resize(8, 0);
+    normalized_usize
 }
 
 /* Old conversion utilities between different libraries data types

rln/tests/ffi.rs

@@ -3,8 +3,8 @@ mod test {
     use ark_std::{rand::thread_rng, UniformRand};
     use rand::Rng;
     use rln::circuit::*;
-    use rln::ffi::*;
-    use rln::poseidon_hash::poseidon_hash;
+    use rln::ffi::{hash as ffi_hash, poseidon_hash as ffi_poseidon_hash, *};
+    use rln::hashers::{hash_to_field, poseidon_hash as utils_poseidon_hash, ROUND_PARAMS};
     use rln::protocol::*;
     use rln::public::RLN;
     use rln::utils::*;
@@ -78,7 +78,7 @@ mod test {
         assert!(success, "set tree call failed");
 
         // We add leaves in a batch into the tree
-        let leaves_ser = vec_fr_to_bytes_le(&leaves);
+        let leaves_ser = vec_fr_to_bytes_le(&leaves).unwrap();
         let input_buffer = &Buffer::from(leaves_ser.as_ref());
         let success = init_tree_with_leaves(rln_pointer, input_buffer);
         assert!(success, "init tree with leaves call failed");
@@ -153,7 +153,7 @@ mod test {
         let set_index = rng.gen_range(0..no_of_leaves) as usize;
 
         // We add leaves in a batch into the tree
-        let leaves_ser = vec_fr_to_bytes_le(&leaves);
+        let leaves_ser = vec_fr_to_bytes_le(&leaves).unwrap();
         let input_buffer = &Buffer::from(leaves_ser.as_ref());
         let success = init_tree_with_leaves(rln_pointer, input_buffer);
         assert!(success, "init tree with leaves call failed");
@@ -170,13 +170,13 @@ mod test {
         // `init_tree_with_leaves` resets the tree to the height it was initialized with, using `set_tree`
 
         // We add leaves in a batch starting from index 0..set_index
-        let leaves_m = vec_fr_to_bytes_le(&leaves[0..set_index]);
+        let leaves_m = vec_fr_to_bytes_le(&leaves[0..set_index]).unwrap();
         let buffer = &Buffer::from(leaves_m.as_ref());
         let success = init_tree_with_leaves(rln_pointer, buffer);
         assert!(success, "init tree with leaves call failed");
 
         // We add the remaining n leaves in a batch starting from index set_index
-        let leaves_n = vec_fr_to_bytes_le(&leaves[set_index..]);
+        let leaves_n = vec_fr_to_bytes_le(&leaves[set_index..]).unwrap();
         let buffer = &Buffer::from(leaves_n.as_ref());
         let success = set_leaves_from(rln_pointer, set_index, buffer);
         assert!(success, "set leaves from call failed");
@@ -248,7 +248,7 @@ mod test {
         let (root_empty, _) = bytes_le_to_fr(&result_data);
 
         // We add leaves in a batch into the tree
-        let leaves = vec_fr_to_bytes_le(&leaves);
+        let leaves = vec_fr_to_bytes_le(&leaves).unwrap();
         let buffer = &Buffer::from(leaves.as_ref());
         let success = set_leaves_from(rln_pointer, bad_index, buffer);
         assert!(!success, "set leaves from call succeeded");
@@ -280,7 +280,7 @@ mod test {
 
         // generate identity
         let identity_secret_hash = hash_to_field(b"test-merkle-proof");
-        let id_commitment = poseidon_hash(&vec![identity_secret_hash]);
+        let id_commitment = utils_poseidon_hash(&vec![identity_secret_hash]);
 
         // We prepare id_commitment and we set the leaf at provided index
         let leaf_ser = fr_to_bytes_le(&id_commitment);
@@ -303,71 +303,86 @@ mod test {
         let output_buffer = unsafe { output_buffer.assume_init() };
         let result_data = <&[u8]>::from(&output_buffer).to_vec();
 
-        let (path_elements, read) = bytes_le_to_vec_fr(&result_data);
-        let (identity_path_index, _) = bytes_le_to_vec_u8(&result_data[read..].to_vec());
+        let (path_elements, read) = bytes_le_to_vec_fr(&result_data).unwrap();
+        let (identity_path_index, _) = bytes_le_to_vec_u8(&result_data[read..].to_vec()).unwrap();
 
         // We check correct computation of the path and indexes
         let mut expected_path_elements = vec![
             str_to_fr(
                 "0x0000000000000000000000000000000000000000000000000000000000000000",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2098f5fb9e239eab3ceac3f27b81e481dc3124d55ffed523a839ee8446b64864",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1069673dcdb12263df301a6ff584a7ec261a44cb9dc68df067a4774460b1f1e1",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x18f43331537ee2af2e3d758d50f72106467c6eea50371dd528d57eb2b856d238",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x07f9d837cb17b0d36320ffe93ba52345f1b728571a568265caac97559dbc952a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2b94cf5e8746b3f5c9631f4c5df32907a699c58c94b2ad4d7b5cec1639183f55",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2dee93c5a666459646ea7d22cca9e1bcfed71e6951b953611d11dda32ea09d78",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x078295e5a22b84e982cf601eb639597b8b0515a88cb5ac7fa8a4aabe3c87349d",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2fa5e5f18f6027a6501bec864564472a616b2e274a41211a444cbe3a99f3cc61",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x0e884376d0d8fd21ecb780389e941f66e45e7acce3e228ab3e2156a614fcd747",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1b7201da72494f1e28717ad1a52eb469f95892f957713533de6175e5da190af2",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1f8d8822725e36385200c0b201249819a6e6e1e4650808b5bebc6bface7d7636",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2c5d82f66c914bafb9701589ba8cfcfb6162b0a12acf88a8d0879a0471b5f85a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x14c54148a0940bb820957f5adf3fa1134ef5c4aaa113f4646458f270e0bfbfd0",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x190d33b12f986f961e10c0ee44d8b9af11be25588cad89d416118e4bf4ebe80c",
                 16,
-            ),
+            )
+            .unwrap(),
         ];
 
         let mut expected_identity_path_index: Vec<u8> =
@@ -379,19 +394,23 @@ mod test {
                 str_to_fr(
                     "0x22f98aa9ce704152ac17354914ad73ed1167ae6596af510aa5b3649325e06c92",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x2a7c7c9b6ce5880b9f6f228d72bf6a575a526f29c66ecceef8b753d38bba7323",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x2e8186e558698ec1c67af9c14d463ffc470043c9c2988b954d75dd643f36b992",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x0f57c5571e9a4eab49e2c8cf050dae948aef6ead647392273546249d1c1ff10f",
                     16,
-                ),
+                )
+                .unwrap(),
             ]);
             expected_identity_path_index.append(&mut vec![0, 0, 0, 0]);
         }
@@ -400,7 +419,8 @@ mod test {
             expected_path_elements.append(&mut vec![str_to_fr(
                 "0x1830ee67b5fb554ad5f63d4388800e1cfe78e310697d46e43c9ce36134f72cca",
                 16,
-            )]);
+            )
+            .unwrap()]);
             expected_identity_path_index.append(&mut vec![0]);
         }
 
@@ -439,7 +459,7 @@ mod test {
             let proof_values = proof_values_from_witness(&rln_witness);
 
             // We prepare id_commitment and we set the leaf at provided index
-            let rln_witness_ser = serialize_witness(&rln_witness);
+            let rln_witness_ser = serialize_witness(&rln_witness).unwrap();
             let input_buffer = &Buffer::from(rln_witness_ser.as_ref());
             let mut output_buffer = MaybeUninit::<Buffer>::uninit();
             let now = Instant::now();
@@ -569,7 +589,7 @@ mod test {
         let rln_pointer = unsafe { &mut *rln_pointer.assume_init() };
 
         // We add leaves in a batch into the tree
-        let leaves_ser = vec_fr_to_bytes_le(&leaves);
+        let leaves_ser = vec_fr_to_bytes_le(&leaves).unwrap();
         let input_buffer = &Buffer::from(leaves_ser.as_ref());
         let success = init_tree_with_leaves(rln_pointer, input_buffer);
         assert!(success, "init tree with leaves call failed");
@@ -589,12 +609,11 @@ mod test {
         let success = set_next_leaf(rln_pointer, input_buffer);
         assert!(success, "set next leaf call failed");
 
-        let identity_index: u64 = no_of_leaves;
+        let identity_index: usize = no_of_leaves;
 
         // We generate a random signal
         let mut rng = rand::thread_rng();
         let signal: [u8; 32] = rng.gen();
-        let signal_len = u64::try_from(signal.len()).unwrap();
 
         // We generate a random epoch
         let epoch = hash_to_field(b"test-epoch");
@@ -603,9 +622,9 @@ mod test {
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         let mut serialized: Vec<u8> = Vec::new();
         serialized.append(&mut fr_to_bytes_le(&identity_secret_hash));
-        serialized.append(&mut identity_index.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(identity_index));
         serialized.append(&mut fr_to_bytes_le(&epoch));
-        serialized.append(&mut signal_len.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(signal.len()));
         serialized.append(&mut signal.to_vec());
 
         // We call generate_rln_proof
@@ -620,7 +639,7 @@ mod test {
         // We prepare input for verify_rln_proof API
         // input_data is [ proof<128> | share_y<32> | nullifier<32> | root<32> | epoch<32> | share_x<32> | rln_identifier<32> | signal_len<8> | signal<var> ]
         // that is [ proof_data | signal_len<8> | signal<var> ]
-        proof_data.append(&mut signal_len.to_le_bytes().to_vec());
+        proof_data.append(&mut normalize_usize(signal.len()));
         proof_data.append(&mut signal.to_vec());
 
         // We call verify_rln_proof
@@ -654,7 +673,7 @@ mod test {
         let rln_pointer = unsafe { &mut *rln_pointer.assume_init() };
 
         // We add leaves in a batch into the tree
-        let leaves_ser = vec_fr_to_bytes_le(&leaves);
+        let leaves_ser = vec_fr_to_bytes_le(&leaves).unwrap();
         let input_buffer = &Buffer::from(leaves_ser.as_ref());
         let success = init_tree_with_leaves(rln_pointer, input_buffer);
         assert!(success, "set leaves call failed");
@@ -674,12 +693,11 @@ mod test {
         let success = set_next_leaf(rln_pointer, input_buffer);
         assert!(success, "set next leaf call failed");
 
-        let identity_index: u64 = no_of_leaves;
+        let identity_index: usize = no_of_leaves;
 
         // We generate a random signal
         let mut rng = rand::thread_rng();
         let signal: [u8; 32] = rng.gen();
-        let signal_len = u64::try_from(signal.len()).unwrap();
 
         // We generate a random epoch
         let epoch = hash_to_field(b"test-epoch");
@@ -688,9 +706,9 @@ mod test {
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         let mut serialized: Vec<u8> = Vec::new();
         serialized.append(&mut fr_to_bytes_le(&identity_secret_hash));
-        serialized.append(&mut identity_index.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(identity_index));
         serialized.append(&mut fr_to_bytes_le(&epoch));
-        serialized.append(&mut signal_len.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(signal.len()));
         serialized.append(&mut signal.to_vec());
 
         // We call generate_rln_proof
@@ -705,7 +723,7 @@ mod test {
         // We prepare input for verify_rln_proof API
         // input_data is [ proof<128> | share_y<32> | nullifier<32> | root<32> | epoch<32> | share_x<32> | rln_identifier<32> | signal_len<8> | signal<var> ]
         // that is [ proof_data | signal_len<8> | signal<var> ]
-        proof_data.append(&mut signal_len.to_le_bytes().to_vec());
+        proof_data.append(&mut normalize_usize(signal.len()));
         proof_data.append(&mut signal.to_vec());
 
         // We test verify_with_roots
@@ -787,18 +805,16 @@ mod test {
         let success = set_next_leaf(rln_pointer, input_buffer);
         assert!(success, "set next leaf call failed");
 
-        let identity_index: u64 = 0;
+        let identity_index: usize = 0;
 
         // We generate two proofs using same epoch but different signals.
 
         // We generate two random signals
         let mut rng = rand::thread_rng();
         let signal1: [u8; 32] = rng.gen();
-        let signal1_len = u64::try_from(signal1.len()).unwrap();
 
         // We generate two random signals
         let signal2: [u8; 32] = rng.gen();
-        let signal2_len = u64::try_from(signal2.len()).unwrap();
 
         // We generate a random epoch
         let epoch = hash_to_field(b"test-epoch");
@@ -807,18 +823,18 @@ mod test {
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         let mut serialized1: Vec<u8> = Vec::new();
         serialized1.append(&mut fr_to_bytes_le(&identity_secret_hash));
-        serialized1.append(&mut identity_index.to_le_bytes().to_vec());
+        serialized1.append(&mut normalize_usize(identity_index));
         serialized1.append(&mut fr_to_bytes_le(&epoch));
 
         // The first part is the same for both proof input, so we clone
         let mut serialized2 = serialized1.clone();
 
         // We attach the first signal to the first proof input
-        serialized1.append(&mut signal1_len.to_le_bytes().to_vec());
+        serialized1.append(&mut normalize_usize(signal1.len()));
         serialized1.append(&mut signal1.to_vec());
 
         // We attach the second signal to the first proof input
-        serialized2.append(&mut signal2_len.to_le_bytes().to_vec());
+        serialized2.append(&mut normalize_usize(signal2.len()));
         serialized2.append(&mut signal2.to_vec());
 
         // We call generate_rln_proof for first proof values
@@ -877,20 +893,19 @@ mod test {
         let success = set_next_leaf(rln_pointer, input_buffer);
         assert!(success, "set next leaf call failed");
 
-        let identity_index_new: u64 = 1;
+        let identity_index_new: usize = 1;
 
         // We generate a random signals
         let signal3: [u8; 32] = rng.gen();
-        let signal3_len = u64::try_from(signal3.len()).unwrap();
 
         // We prepare input for generate_rln_proof API
         // input_data is [ identity_secret<32> | id_index<8> | epoch<32> | signal_len<8> | signal<var> ]
         // Note that epoch is the same as before
         let mut serialized: Vec<u8> = Vec::new();
         serialized.append(&mut fr_to_bytes_le(&identity_secret_hash_new));
-        serialized.append(&mut identity_index_new.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(identity_index_new));
         serialized.append(&mut fr_to_bytes_le(&epoch));
-        serialized.append(&mut signal3_len.to_le_bytes().to_vec());
+        serialized.append(&mut normalize_usize(signal3.len()));
         serialized.append(&mut signal3.to_vec());
 
         // We call generate_rln_proof
@@ -957,16 +972,15 @@ mod test {
 
         assert_eq!(
             identity_secret_hash,
-            expected_identity_secret_hash_seed_bytes
+            expected_identity_secret_hash_seed_bytes.unwrap()
         );
-        assert_eq!(id_commitment, expected_id_commitment_seed_bytes);
+        assert_eq!(id_commitment, expected_id_commitment_seed_bytes.unwrap());
     }
 
     #[test]
     // Tests hash to field using FFI APIs
     fn test_seeded_extended_keygen_ffi() {
         let tree_height = TEST_TREE_HEIGHT;
-
         // We create a RLN instance
         let mut rln_pointer = MaybeUninit::<*mut RLN>::uninit();
         let input_buffer = &Buffer::from(TEST_RESOURCES_FOLDER.as_bytes());
@@ -1004,34 +1018,31 @@ mod test {
             16,
         );
 
-        assert_eq!(identity_trapdoor, expected_identity_trapdoor_seed_bytes);
-        assert_eq!(identity_nullifier, expected_identity_nullifier_seed_bytes);
+        assert_eq!(
+            identity_trapdoor,
+            expected_identity_trapdoor_seed_bytes.unwrap()
+        );
+        assert_eq!(
+            identity_nullifier,
+            expected_identity_nullifier_seed_bytes.unwrap()
+        );
         assert_eq!(
             identity_secret_hash,
-            expected_identity_secret_hash_seed_bytes
+            expected_identity_secret_hash_seed_bytes.unwrap()
         );
-        assert_eq!(id_commitment, expected_id_commitment_seed_bytes);
+        assert_eq!(id_commitment, expected_id_commitment_seed_bytes.unwrap());
     }
 
     #[test]
     // Tests hash to field using FFI APIs
     fn test_hash_to_field_ffi() {
-        let tree_height = TEST_TREE_HEIGHT;
-
-        // We create a RLN instance
-        let mut rln_pointer = MaybeUninit::<*mut RLN>::uninit();
-        let input_buffer = &Buffer::from(TEST_RESOURCES_FOLDER.as_bytes());
-        let success = new(tree_height, input_buffer, rln_pointer.as_mut_ptr());
-        assert!(success, "RLN object creation failed");
-        let rln_pointer = unsafe { &mut *rln_pointer.assume_init() };
-
         let mut rng = rand::thread_rng();
         let signal: [u8; 32] = rng.gen();
 
         // We prepare id_commitment and we set the leaf at provided index
         let input_buffer = &Buffer::from(signal.as_ref());
         let mut output_buffer = MaybeUninit::<Buffer>::uninit();
-        let success = hash(rln_pointer, input_buffer, output_buffer.as_mut_ptr());
+        let success = ffi_hash(input_buffer, output_buffer.as_mut_ptr());
         assert!(success, "hash call failed");
         let output_buffer = unsafe { output_buffer.assume_init() };
 
@@ -1043,4 +1054,30 @@ mod test {
 
         assert_eq!(hash1, hash2);
     }
+
+    #[test]
+    // Test Poseidon hash FFI
+    fn test_poseidon_hash_ffi() {
+        // generate random number between 1..ROUND_PARAMS.len()
+        let mut rng = thread_rng();
+        let number_of_inputs = rng.gen_range(1..ROUND_PARAMS.len());
+        let mut inputs = Vec::with_capacity(number_of_inputs);
+        for _ in 0..number_of_inputs {
+            inputs.push(Fr::rand(&mut rng));
+        }
+        let inputs_ser = vec_fr_to_bytes_le(&inputs).unwrap();
+        let input_buffer = &Buffer::from(inputs_ser.as_ref());
+
+        let expected_hash = utils_poseidon_hash(inputs.as_ref());
+
+        let mut output_buffer = MaybeUninit::<Buffer>::uninit();
+        let success = ffi_poseidon_hash(input_buffer, output_buffer.as_mut_ptr());
+        assert!(success, "poseidon hash call failed");
+
+        let output_buffer = unsafe { output_buffer.assume_init() };
+        let result_data = <&[u8]>::from(&output_buffer).to_vec();
+        let (received_hash, _) = bytes_le_to_fr(&result_data);
+
+        assert_eq!(received_hash, expected_hash);
+    }
 }

rln/tests/poseidon_tree.rs

@@ -6,7 +6,7 @@
 mod test {
     use rln::circuit::*;
     use rln::poseidon_tree::*;
-    use utils::{FullMerkleTree, OptimalMerkleTree};
+    use utils::{FullMerkleTree, OptimalMerkleTree, ZerokitMerkleProof, ZerokitMerkleTree};
 
     #[test]
     /// A basic performance comparison between the two supported Merkle Tree implementations
@@ -82,56 +82,38 @@ mod test {
 // Test module for testing pmtree integration and features in zerokit
 // enabled only if the pmtree feature is enabled
 
-#[cfg(feature = "pmtree")]
+#[cfg(feature = "pmtree-ft")]
 #[cfg(test)]
 mod pmtree_test {
 
     use pmtree::*;
     use rln::circuit::Fr;
-    use rln::poseidon_hash::poseidon_hash;
+    use rln::hashers::{hash_to_field, poseidon_hash};
     use rln::poseidon_tree::PoseidonHash;
     use rln::protocol::hash_to_field;
-    use rln::utils::{bytes_le_to_fr, fr_to_bytes_le, str_to_fr};
+    use rln::utils::str_to_fr;
     use sled::Db as Sled;
-    use std::collections::HashMap;
     use std::fs;
-    use std::path::Path;
+    use std::{collections::HashMap, path::PathBuf};
     use utils::{FullMerkleTree, OptimalMerkleTree};
 
-    // The pmtree Hasher trait used by pmtree Merkle tree
-    impl pmtree::Hasher for PoseidonHash {
-        type Fr = Fr;
-
-        fn default_leaf() -> Self::Fr {
-            Fr::from(0)
-        }
-
-        fn serialize(value: Self::Fr) -> Value {
-            fr_to_bytes_le(&value)
-        }
-
-        fn deserialize(value: Value) -> Self::Fr {
-            let (fr, _) = bytes_le_to_fr(&value);
-            fr
-        }
-
-        fn hash(inputs: &[Self::Fr]) -> Self::Fr {
-            poseidon_hash(inputs)
-        }
-    }
-
     // pmtree supports in-memory and on-disk databases (Database trait) for storing the Merkle tree state
 
     // We implement Database for hashmaps, an in-memory database
     struct MemoryDB(HashMap<DBKey, Value>);
 
+    #[derive(Default)]
+    struct MemoryDBConfig {}
+
     impl Database for MemoryDB {
-        fn new(_dbpath: &str) -> Result<Self> {
+        type Config = MemoryDBConfig;
+
+        fn new(_config: Self::Config) -> Result<Self> {
             Ok(MemoryDB(HashMap::new()))
         }
 
-        fn load(_dbpath: &str) -> Result<Self> {
-            Err(Error("Cannot load in-memory DB".to_string()))
+        fn load(_config: Self::Config) -> Result<Self> {
+            Err(Box::new(Error("Cannot load in-memory DB".to_string())))
         }
 
         fn get(&self, key: DBKey) -> Result<Option<Value>> {
@@ -143,36 +125,46 @@ mod pmtree_test {
 
             Ok(())
         }
+
+        fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> Result<()> {
+            self.0.extend(subtree);
+            Ok(())
+        }
     }
 
     // We implement Database for sled DB, an on-disk database
     struct SledDB(Sled);
 
     impl Database for SledDB {
-        fn new(dbpath: &str) -> Result<Self> {
-            if Path::new(dbpath).exists() {
-                match fs::remove_dir_all(dbpath) {
+        type Config = sled::Config;
+
+        fn new(config: Self::Config) -> Result<Self> {
+            let dbpath = config.path;
+            if config.dbpath.exists() {
+                match fs::remove_dir_all(&config.dbpath) {
                     Ok(x) => x,
-                    Err(e) => return Err(Error(e.to_string())),
+                    Err(e) => return Err(Box::new(Error(e.to_string()))),
                 }
             }
 
-            let db: Sled = match sled::open(dbpath) {
+            let db: Sled = match config.open() {
                 Ok(db) => db,
-                Err(e) => return Err(Error(e.to_string())),
+                Err(e) => return Err(Box::new(Error(e.to_string()))),
             };
 
             Ok(SledDB(db))
         }
 
-        fn load(dbpath: &str) -> Result<Self> {
-            let db: Sled = match sled::open(dbpath) {
+        fn load(config: Self::Config) -> Result<Self> {
+            let db: Sled = match sled::open(config.dbpath) {
                 Ok(db) => db,
-                Err(e) => return Err(Error(e.to_string())),
+                Err(e) => return Err(Box::new(Error(e.to_string()))),
             };
 
             if !db.was_recovered() {
-                return Err(Error("Trying to load non-existing database!".to_string()));
+                return Err(Box::new(Error(
+                    "Trying to load non-existing database!".to_string(),
+                )));
             }
 
             Ok(SledDB(db))
@@ -181,16 +173,27 @@ mod pmtree_test {
         fn get(&self, key: DBKey) -> Result<Option<Value>> {
             match self.0.get(key) {
                 Ok(value) => Ok(value.map(|val| val.to_vec())),
-                Err(e) => Err(Error(e.to_string())),
+                Err(e) => Err(Box::new(Error(e.to_string()))),
             }
         }
 
         fn put(&mut self, key: DBKey, value: Value) -> Result<()> {
             match self.0.insert(key, value) {
                 Ok(_) => Ok(()),
-                Err(e) => Err(Error(e.to_string())),
+                Err(e) => Err(Box::new(Error(e.to_string()))),
             }
         }
+
+        fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> Result<()> {
+            let mut batch = sled::Batch::default();
+
+            for (key, value) in subtree {
+                batch.insert(&key, value);
+            }
+
+            self.0.apply_batch(batch)?;
+            Ok(())
+        }
     }
 
     #[test]
@@ -341,6 +344,7 @@ mod pmtree_test {
                 "0x21947ffd0bce0c385f876e7c97d6a42eec5b1fe935aab2f01c1f8a8cbcc356d2",
                 16
             )
+            .unwrap()
         );
 
         let merkle_proof = tree.proof(leaf_index).expect("proof should exist");
@@ -353,83 +357,103 @@ mod pmtree_test {
             str_to_fr(
                 "0x0000000000000000000000000000000000000000000000000000000000000000",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2098f5fb9e239eab3ceac3f27b81e481dc3124d55ffed523a839ee8446b64864",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1069673dcdb12263df301a6ff584a7ec261a44cb9dc68df067a4774460b1f1e1",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x18f43331537ee2af2e3d758d50f72106467c6eea50371dd528d57eb2b856d238",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x07f9d837cb17b0d36320ffe93ba52345f1b728571a568265caac97559dbc952a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2b94cf5e8746b3f5c9631f4c5df32907a699c58c94b2ad4d7b5cec1639183f55",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2dee93c5a666459646ea7d22cca9e1bcfed71e6951b953611d11dda32ea09d78",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x078295e5a22b84e982cf601eb639597b8b0515a88cb5ac7fa8a4aabe3c87349d",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2fa5e5f18f6027a6501bec864564472a616b2e274a41211a444cbe3a99f3cc61",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x0e884376d0d8fd21ecb780389e941f66e45e7acce3e228ab3e2156a614fcd747",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1b7201da72494f1e28717ad1a52eb469f95892f957713533de6175e5da190af2",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1f8d8822725e36385200c0b201249819a6e6e1e4650808b5bebc6bface7d7636",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2c5d82f66c914bafb9701589ba8cfcfb6162b0a12acf88a8d0879a0471b5f85a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x14c54148a0940bb820957f5adf3fa1134ef5c4aaa113f4646458f270e0bfbfd0",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x190d33b12f986f961e10c0ee44d8b9af11be25588cad89d416118e4bf4ebe80c",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x22f98aa9ce704152ac17354914ad73ed1167ae6596af510aa5b3649325e06c92",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2a7c7c9b6ce5880b9f6f228d72bf6a575a526f29c66ecceef8b753d38bba7323",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2e8186e558698ec1c67af9c14d463ffc470043c9c2988b954d75dd643f36b992",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x0f57c5571e9a4eab49e2c8cf050dae948aef6ead647392273546249d1c1ff10f",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1830ee67b5fb554ad5f63d4388800e1cfe78e310697d46e43c9ce36134f72cca",
                 16,
-            ),
+            )
+            .unwrap(),
         ];
 
         let expected_identity_path_index: Vec<u8> =
@@ -467,6 +491,7 @@ mod pmtree_test {
                 "0x21947ffd0bce0c385f876e7c97d6a42eec5b1fe935aab2f01c1f8a8cbcc356d2",
                 16
             )
+            .unwrap()
         );
 
         let merkle_proof = tree.proof(leaf_index).expect("proof should exist");
@@ -479,83 +504,103 @@ mod pmtree_test {
             str_to_fr(
                 "0x0000000000000000000000000000000000000000000000000000000000000000",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2098f5fb9e239eab3ceac3f27b81e481dc3124d55ffed523a839ee8446b64864",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1069673dcdb12263df301a6ff584a7ec261a44cb9dc68df067a4774460b1f1e1",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x18f43331537ee2af2e3d758d50f72106467c6eea50371dd528d57eb2b856d238",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x07f9d837cb17b0d36320ffe93ba52345f1b728571a568265caac97559dbc952a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2b94cf5e8746b3f5c9631f4c5df32907a699c58c94b2ad4d7b5cec1639183f55",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2dee93c5a666459646ea7d22cca9e1bcfed71e6951b953611d11dda32ea09d78",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x078295e5a22b84e982cf601eb639597b8b0515a88cb5ac7fa8a4aabe3c87349d",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2fa5e5f18f6027a6501bec864564472a616b2e274a41211a444cbe3a99f3cc61",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x0e884376d0d8fd21ecb780389e941f66e45e7acce3e228ab3e2156a614fcd747",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1b7201da72494f1e28717ad1a52eb469f95892f957713533de6175e5da190af2",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1f8d8822725e36385200c0b201249819a6e6e1e4650808b5bebc6bface7d7636",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2c5d82f66c914bafb9701589ba8cfcfb6162b0a12acf88a8d0879a0471b5f85a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x14c54148a0940bb820957f5adf3fa1134ef5c4aaa113f4646458f270e0bfbfd0",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x190d33b12f986f961e10c0ee44d8b9af11be25588cad89d416118e4bf4ebe80c",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x22f98aa9ce704152ac17354914ad73ed1167ae6596af510aa5b3649325e06c92",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2a7c7c9b6ce5880b9f6f228d72bf6a575a526f29c66ecceef8b753d38bba7323",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2e8186e558698ec1c67af9c14d463ffc470043c9c2988b954d75dd643f36b992",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x0f57c5571e9a4eab49e2c8cf050dae948aef6ead647392273546249d1c1ff10f",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1830ee67b5fb554ad5f63d4388800e1cfe78e310697d46e43c9ce36134f72cca",
                 16,
-            ),
+            )
+            .unwrap(),
         ];
 
         let expected_identity_path_index: Vec<u8> =

rln/tests/protocol.rs

@@ -4,10 +4,11 @@ mod test {
         circom_from_folder, vk_from_folder, zkey_from_folder, Fr, TEST_RESOURCES_FOLDER,
         TEST_TREE_HEIGHT,
     };
-    use rln::poseidon_hash::poseidon_hash;
+    use rln::hashers::{hash_to_field, poseidon_hash};
     use rln::poseidon_tree::PoseidonTree;
     use rln::protocol::*;
     use rln::utils::str_to_fr;
+    use utils::{ZerokitMerkleProof, ZerokitMerkleTree};
 
     // Input generated with https://github.com/oskarth/zk-kit/commit/b6a872f7160c7c14e10a0ea40acab99cbb23c9a8
     const WITNESS_JSON_15: &str = r#"
@@ -184,6 +185,7 @@ mod test {
                     "0x1984f2e01184aef5cb974640898a5f5c25556554e2b06d99d4841badb8b198cd",
                     16
                 )
+                .unwrap()
             );
         } else if TEST_TREE_HEIGHT == 19 {
             assert_eq!(
@@ -192,6 +194,7 @@ mod test {
                     "0x219ceb53f2b1b7a6cf74e80d50d44d68ecb4a53c6cc65b25593c8d56343fb1fe",
                     16
                 )
+                .unwrap()
             );
         } else if TEST_TREE_HEIGHT == 20 {
             assert_eq!(
@@ -200,6 +203,7 @@ mod test {
                     "0x21947ffd0bce0c385f876e7c97d6a42eec5b1fe935aab2f01c1f8a8cbcc356d2",
                     16
                 )
+                .unwrap()
             );
         }
 
@@ -213,63 +217,78 @@ mod test {
             str_to_fr(
                 "0x0000000000000000000000000000000000000000000000000000000000000000",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2098f5fb9e239eab3ceac3f27b81e481dc3124d55ffed523a839ee8446b64864",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1069673dcdb12263df301a6ff584a7ec261a44cb9dc68df067a4774460b1f1e1",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x18f43331537ee2af2e3d758d50f72106467c6eea50371dd528d57eb2b856d238",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x07f9d837cb17b0d36320ffe93ba52345f1b728571a568265caac97559dbc952a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2b94cf5e8746b3f5c9631f4c5df32907a699c58c94b2ad4d7b5cec1639183f55",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2dee93c5a666459646ea7d22cca9e1bcfed71e6951b953611d11dda32ea09d78",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x078295e5a22b84e982cf601eb639597b8b0515a88cb5ac7fa8a4aabe3c87349d",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2fa5e5f18f6027a6501bec864564472a616b2e274a41211a444cbe3a99f3cc61",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x0e884376d0d8fd21ecb780389e941f66e45e7acce3e228ab3e2156a614fcd747",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1b7201da72494f1e28717ad1a52eb469f95892f957713533de6175e5da190af2",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1f8d8822725e36385200c0b201249819a6e6e1e4650808b5bebc6bface7d7636",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2c5d82f66c914bafb9701589ba8cfcfb6162b0a12acf88a8d0879a0471b5f85a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x14c54148a0940bb820957f5adf3fa1134ef5c4aaa113f4646458f270e0bfbfd0",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x190d33b12f986f961e10c0ee44d8b9af11be25588cad89d416118e4bf4ebe80c",
                 16,
-            ),
+            )
+            .unwrap(),
         ];
 
         let mut expected_identity_path_index: Vec<u8> =
@@ -281,19 +300,23 @@ mod test {
                 str_to_fr(
                     "0x22f98aa9ce704152ac17354914ad73ed1167ae6596af510aa5b3649325e06c92",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x2a7c7c9b6ce5880b9f6f228d72bf6a575a526f29c66ecceef8b753d38bba7323",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x2e8186e558698ec1c67af9c14d463ffc470043c9c2988b954d75dd643f36b992",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x0f57c5571e9a4eab49e2c8cf050dae948aef6ead647392273546249d1c1ff10f",
                     16,
-                ),
+                )
+                .unwrap(),
             ]);
             expected_identity_path_index.append(&mut vec![0, 0, 0, 0]);
         }
@@ -302,7 +325,8 @@ mod test {
             expected_path_elements.append(&mut vec![str_to_fr(
                 "0x1830ee67b5fb554ad5f63d4388800e1cfe78e310697d46e43c9ce36134f72cca",
                 16,
-            )]);
+            )
+            .unwrap()]);
             expected_identity_path_index.append(&mut vec![0]);
         }
 
@@ -319,7 +343,7 @@ mod test {
         // We generate all relevant keys
         let proving_key = zkey_from_folder(TEST_RESOURCES_FOLDER).unwrap();
         let verification_key = vk_from_folder(TEST_RESOURCES_FOLDER).unwrap();
-        let builder = circom_from_folder(TEST_RESOURCES_FOLDER);
+        let builder = circom_from_folder(TEST_RESOURCES_FOLDER).unwrap();
 
         // We compute witness from the json input example
         let mut witness_json: &str = "";
@@ -334,10 +358,12 @@ mod test {
 
         let rln_witness = rln_witness_from_json(witness_json);
 
-        // Let's generate a zkSNARK proof
-        let proof = generate_proof(builder, &proving_key, &rln_witness).unwrap();
+        let rln_witness_unwrapped = rln_witness.unwrap();
 
-        let proof_values = proof_values_from_witness(&rln_witness);
+        // Let's generate a zkSNARK proof
+        let proof = generate_proof(builder, &proving_key, &rln_witness_unwrapped).unwrap();
+
+        let proof_values = proof_values_from_witness(&rln_witness_unwrapped);
 
         // Let's verify the proof
         let verified = verify_proof(&verification_key, &proof, &proof_values);
@@ -378,7 +404,7 @@ mod test {
         // We generate all relevant keys
         let proving_key = zkey_from_folder(TEST_RESOURCES_FOLDER).unwrap();
         let verification_key = vk_from_folder(TEST_RESOURCES_FOLDER).unwrap();
-        let builder = circom_from_folder(TEST_RESOURCES_FOLDER);
+        let builder = circom_from_folder(TEST_RESOURCES_FOLDER).unwrap();
 
         // Let's generate a zkSNARK proof
         let proof = generate_proof(builder, &proving_key, &rln_witness).unwrap();
@@ -404,10 +430,10 @@ mod test {
             witness_json = WITNESS_JSON_20;
         }
 
-        let rln_witness = rln_witness_from_json(witness_json);
+        let rln_witness = rln_witness_from_json(witness_json).unwrap();
 
-        let ser = serialize_witness(&rln_witness);
-        let (deser, _) = deserialize_witness(&ser);
+        let ser = serialize_witness(&rln_witness).unwrap();
+        let (deser, _) = deserialize_witness(&ser).unwrap();
         assert_eq!(rln_witness, deser);
 
         // We test Proof values serialization
@@ -429,11 +455,13 @@ mod test {
         let expected_identity_secret_hash_seed_phrase = str_to_fr(
             "0x20df38f3f00496f19fe7c6535492543b21798ed7cb91aebe4af8012db884eda3",
             16,
-        );
+        )
+        .unwrap();
         let expected_id_commitment_seed_phrase = str_to_fr(
             "0x1223a78a5d66043a7f9863e14507dc80720a5602b2a894923e5b5147d5a9c325",
             16,
-        );
+        )
+        .unwrap();
 
         assert_eq!(
             identity_secret_hash,
@@ -449,11 +477,13 @@ mod test {
         let expected_identity_secret_hash_seed_bytes = str_to_fr(
             "0x766ce6c7e7a01bdf5b3f257616f603918c30946fa23480f2859c597817e6716",
             16,
-        );
+        )
+        .unwrap();
         let expected_id_commitment_seed_bytes = str_to_fr(
             "0xbf16d2b5c0d6f9d9d561e05bfca16a81b4b873bb063508fae360d8c74cef51f",
             16,
-        );
+        )
+        .unwrap();
 
         assert_eq!(
             identity_secret_hash,

rln/tests/public.rs

@@ -1,10 +1,11 @@
 #[cfg(test)]
 mod test {
+    use ark_std::{rand::thread_rng, UniformRand};
     use rand::Rng;
-    use rln::circuit::{TEST_RESOURCES_FOLDER, TEST_TREE_HEIGHT};
-    use rln::poseidon_hash::poseidon_hash;
-    use rln::protocol::{compute_tree_root, deserialize_identity_tuple, hash_to_field};
-    use rln::public::RLN;
+    use rln::circuit::{Fr, TEST_RESOURCES_FOLDER, TEST_TREE_HEIGHT};
+    use rln::hashers::{hash_to_field, poseidon_hash as utils_poseidon_hash, ROUND_PARAMS};
+    use rln::protocol::{compute_tree_root, deserialize_identity_tuple};
+    use rln::public::{hash as public_hash, poseidon_hash as public_poseidon_hash, RLN};
     use rln::utils::*;
     use std::io::Cursor;
 
@@ -15,11 +16,11 @@ mod test {
         let leaf_index = 3;
 
         let input_buffer = Cursor::new(TEST_RESOURCES_FOLDER);
-        let mut rln = RLN::new(tree_height, input_buffer);
+        let mut rln = RLN::new(tree_height, input_buffer).unwrap();
 
         // generate identity
         let identity_secret_hash = hash_to_field(b"test-merkle-proof");
-        let id_commitment = poseidon_hash(&vec![identity_secret_hash]);
+        let id_commitment = utils_poseidon_hash(&vec![identity_secret_hash]);
 
         // We pass id_commitment as Read buffer to RLN's set_leaf
         let mut buffer = Cursor::new(fr_to_bytes_le(&id_commitment));
@@ -37,6 +38,7 @@ mod test {
                     "0x1984f2e01184aef5cb974640898a5f5c25556554e2b06d99d4841badb8b198cd",
                     16
                 )
+                .unwrap()
             );
         } else if TEST_TREE_HEIGHT == 19 {
             assert_eq!(
@@ -45,6 +47,7 @@ mod test {
                     "0x219ceb53f2b1b7a6cf74e80d50d44d68ecb4a53c6cc65b25593c8d56343fb1fe",
                     16
                 )
+                .unwrap()
             );
         } else if TEST_TREE_HEIGHT == 20 {
             assert_eq!(
@@ -53,6 +56,7 @@ mod test {
                     "0x21947ffd0bce0c385f876e7c97d6a42eec5b1fe935aab2f01c1f8a8cbcc356d2",
                     16
                 )
+                .unwrap()
             );
         }
 
@@ -61,71 +65,86 @@ mod test {
         rln.get_proof(leaf_index, &mut buffer).unwrap();
 
         let buffer_inner = buffer.into_inner();
-        let (path_elements, read) = bytes_le_to_vec_fr(&buffer_inner);
-        let (identity_path_index, _) = bytes_le_to_vec_u8(&buffer_inner[read..].to_vec());
+        let (path_elements, read) = bytes_le_to_vec_fr(&buffer_inner).unwrap();
+        let (identity_path_index, _) = bytes_le_to_vec_u8(&buffer_inner[read..].to_vec()).unwrap();
 
         // We check correct computation of the path and indexes
         let mut expected_path_elements = vec![
             str_to_fr(
                 "0x0000000000000000000000000000000000000000000000000000000000000000",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2098f5fb9e239eab3ceac3f27b81e481dc3124d55ffed523a839ee8446b64864",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1069673dcdb12263df301a6ff584a7ec261a44cb9dc68df067a4774460b1f1e1",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x18f43331537ee2af2e3d758d50f72106467c6eea50371dd528d57eb2b856d238",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x07f9d837cb17b0d36320ffe93ba52345f1b728571a568265caac97559dbc952a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2b94cf5e8746b3f5c9631f4c5df32907a699c58c94b2ad4d7b5cec1639183f55",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2dee93c5a666459646ea7d22cca9e1bcfed71e6951b953611d11dda32ea09d78",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x078295e5a22b84e982cf601eb639597b8b0515a88cb5ac7fa8a4aabe3c87349d",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2fa5e5f18f6027a6501bec864564472a616b2e274a41211a444cbe3a99f3cc61",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x0e884376d0d8fd21ecb780389e941f66e45e7acce3e228ab3e2156a614fcd747",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1b7201da72494f1e28717ad1a52eb469f95892f957713533de6175e5da190af2",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x1f8d8822725e36385200c0b201249819a6e6e1e4650808b5bebc6bface7d7636",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x2c5d82f66c914bafb9701589ba8cfcfb6162b0a12acf88a8d0879a0471b5f85a",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x14c54148a0940bb820957f5adf3fa1134ef5c4aaa113f4646458f270e0bfbfd0",
                 16,
-            ),
+            )
+            .unwrap(),
             str_to_fr(
                 "0x190d33b12f986f961e10c0ee44d8b9af11be25588cad89d416118e4bf4ebe80c",
                 16,
-            ),
+            )
+            .unwrap(),
         ];
 
         let mut expected_identity_path_index: Vec<u8> =
@@ -137,19 +156,23 @@ mod test {
                 str_to_fr(
                     "0x22f98aa9ce704152ac17354914ad73ed1167ae6596af510aa5b3649325e06c92",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x2a7c7c9b6ce5880b9f6f228d72bf6a575a526f29c66ecceef8b753d38bba7323",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x2e8186e558698ec1c67af9c14d463ffc470043c9c2988b954d75dd643f36b992",
                     16,
-                ),
+                )
+                .unwrap(),
                 str_to_fr(
                     "0x0f57c5571e9a4eab49e2c8cf050dae948aef6ead647392273546249d1c1ff10f",
                     16,
-                ),
+                )
+                .unwrap(),
             ]);
             expected_identity_path_index.append(&mut vec![0, 0, 0, 0]);
         }
@@ -158,7 +181,8 @@ mod test {
             expected_path_elements.append(&mut vec![str_to_fr(
                 "0x1830ee67b5fb554ad5f63d4388800e1cfe78e310697d46e43c9ce36134f72cca",
                 16,
-            )]);
+            )
+            .unwrap()]);
             expected_identity_path_index.append(&mut vec![0]);
         }
 
@@ -192,11 +216,13 @@ mod test {
         let expected_identity_secret_hash_seed_bytes = str_to_fr(
             "0x766ce6c7e7a01bdf5b3f257616f603918c30946fa23480f2859c597817e6716",
             16,
-        );
+        )
+        .unwrap();
         let expected_id_commitment_seed_bytes = str_to_fr(
             "0xbf16d2b5c0d6f9d9d561e05bfca16a81b4b873bb063508fae360d8c74cef51f",
             16,
-        );
+        )
+        .unwrap();
 
         assert_eq!(
             identity_secret_hash,
@@ -225,19 +251,23 @@ mod test {
         let expected_identity_trapdoor_seed_bytes = str_to_fr(
             "0x766ce6c7e7a01bdf5b3f257616f603918c30946fa23480f2859c597817e6716",
             16,
-        );
+        )
+        .unwrap();
         let expected_identity_nullifier_seed_bytes = str_to_fr(
             "0x1f18714c7bc83b5bca9e89d404cf6f2f585bc4c0f7ed8b53742b7e2b298f50b4",
             16,
-        );
+        )
+        .unwrap();
         let expected_identity_secret_hash_seed_bytes = str_to_fr(
             "0x2aca62aaa7abaf3686fff2caf00f55ab9462dc12db5b5d4bcf3994e671f8e521",
             16,
-        );
+        )
+        .unwrap();
         let expected_id_commitment_seed_bytes = str_to_fr(
             "0x68b66aa0a8320d2e56842581553285393188714c48f9b17acd198b4f1734c5c",
             16,
-        );
+        )
+        .unwrap();
 
         assert_eq!(identity_trapdoor, expected_identity_trapdoor_seed_bytes);
         assert_eq!(identity_nullifier, expected_identity_nullifier_seed_bytes);
@@ -250,15 +280,13 @@ mod test {
 
     #[test]
     fn test_hash_to_field() {
-        let rln = RLN::default();
-
-        let mut rng = rand::thread_rng();
+        let mut rng = thread_rng();
         let signal: [u8; 32] = rng.gen();
 
         let mut input_buffer = Cursor::new(&signal);
         let mut output_buffer = Cursor::new(Vec::<u8>::new());
 
-        rln.hash(&mut input_buffer, &mut output_buffer).unwrap();
+        public_hash(&mut input_buffer, &mut output_buffer).unwrap();
         let serialized_hash = output_buffer.into_inner();
         let (hash1, _) = bytes_le_to_fr(&serialized_hash);
 
@@ -266,4 +294,24 @@ mod test {
 
         assert_eq!(hash1, hash2);
     }
+
+    #[test]
+    fn test_poseidon_hash() {
+        let mut rng = thread_rng();
+        let number_of_inputs = rng.gen_range(1..ROUND_PARAMS.len());
+        let mut inputs = Vec::with_capacity(number_of_inputs);
+        for _ in 0..number_of_inputs {
+            inputs.push(Fr::rand(&mut rng));
+        }
+        let expected_hash = utils_poseidon_hash(&inputs);
+
+        let mut input_buffer = Cursor::new(vec_fr_to_bytes_le(&inputs).unwrap());
+        let mut output_buffer = Cursor::new(Vec::<u8>::new());
+
+        public_poseidon_hash(&mut input_buffer, &mut output_buffer).unwrap();
+        let serialized_hash = output_buffer.into_inner();
+        let (hash, _) = bytes_le_to_fr(&serialized_hash);
+
+        assert_eq!(hash, expected_hash);
+    }
 }

semaphore/Cargo.toml

@@ -2,6 +2,7 @@
 name = "semaphore-wrapper"
 version = "0.1.0"
 edition = "2021"
+license = "MIT OR Apache-2.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -11,13 +12,12 @@ dylib = [ "wasmer/dylib", "wasmer-engine-dylib", "wasmer-compiler-cranelift" ]
 
 [dependencies]
 ark-bn254 = { version = "0.3.0" }
-ark-circom = { git = "https://github.com/gakonst/ark-circom", features=["circom-2"] }
+ark-circom = { git = "https://github.com/gakonst/ark-circom", features=["circom-2"], rev = "35ce5a9" }
 ark-ec = { version = "0.3.0", default-features = false, features = ["parallel"] }
 ark-groth16 = { git = "https://github.com/arkworks-rs/groth16", rev = "765817f", features = ["parallel"] }
 ark-relations = { version = "0.3.0", default-features = false }
 ark-std = { version = "0.3.0", default-features = false, features = ["parallel"] }
-color-eyre = "0.5"
-num-bigint = { version = "0.4", default-features = false, features = ["rand"] }
+color-eyre = "0.6.1"
 once_cell = "1.8"
 rand = "0.8.4"
 semaphore = { git = "https://github.com/worldcoin/semaphore-rs", rev = "ee658c2"}
@@ -32,10 +32,10 @@ rand_chacha = "0.3.1"
 serde_json = "1.0.79"
 
 [build-dependencies]
-color-eyre = "0.5"
+color-eyre = "0.6.1"
 wasmer = { version = "2.0" }
 wasmer-engine-dylib = { version = "2.2.1", optional = true }
-wasmer-compiler-cranelift = { version = "2.2.1", optional = true }
+wasmer-compiler-cranelift = { version = "3.1.1", optional = true }
 
 [profile.release]
 codegen-units = 1
@@ -47,4 +47,4 @@ opt-level = 3
 # Dependencies are optimized, even in a dev build. This improves dev performance
 # while having neglible impact on incremental build times.
 [profile.dev.package."*"]
-opt-level = 3
+opt-level = 3

semaphore/README.md

@@ -8,3 +8,11 @@ Goal is also to provide a basic FFI around protocol.rs, which is currently not
 in scope for that project.
 
 See that project for more information.
+
+## Build and Test
+
+To build and test, run the following commands within the module folder
+```bash
+cargo make build
+cargo make test
+```

semaphore/build.rs

@@ -37,7 +37,7 @@ fn build_circuit() -> Result<()> {
             .current_dir("./vendor/semaphore")
             .status()?
             .success()
-            .then(|| ())
+            .then_some(())
             .ok_or(eyre!("procees returned failure"))?;
         Ok(())
     };

semaphore/src/circuit.rs

@@ -50,7 +50,7 @@ fn from_dylib(path: &Path) -> Mutex<WitnessCalculator> {
 
 #[must_use]
 pub fn zkey() -> &'static (ProvingKey<Bn254>, ConstraintMatrices<Fr>) {
-    &*ZKEY
+    &ZKEY
 }
 
 #[cfg(feature = "dylib")]

semaphore/src/protocol.rs

@@ -12,7 +12,7 @@ use ark_groth16::{
 };
 use ark_relations::r1cs::SynthesisError;
 use ark_std::UniformRand;
-use color_eyre::Result;
+use color_eyre::{Report, Result};
 use ethers_core::types::U256;
 use rand::{thread_rng, Rng};
 use semaphore::{
@@ -89,7 +89,7 @@ pub enum ProofError {
     #[error("Error reading circuit key: {0}")]
     CircuitKeyError(#[from] std::io::Error),
     #[error("Error producing witness: {0}")]
-    WitnessError(color_eyre::Report),
+    WitnessError(Report),
     #[error("Error producing proof: {0}")]
     SynthesisError(#[from] SynthesisError),
     #[error("Error converting public input: {0}")]

utils/Cargo.toml

@@ -2,13 +2,15 @@
 name = "utils"
 version = "0.1.0"
 edition = "2021"
+license = "MIT OR Apache-2.0"
 
 [dependencies]
-ark-ff = { version = "0.3.0", default-features = false, features = ["asm"] }
-num-bigint = { version = "0.4.3", default-features = false, features = ["rand"] }
+ark-ff = { version = "=0.4.1", default-features = false, features = ["asm"] }
+num-bigint = { version = "=0.4.3", default-features = false, features = ["rand"] }
+color-eyre = "=0.6.2"
 
 [dev-dependencies]
-ark-bn254 = { version = "0.3.0" }
+ark-bn254 = "=0.4.0"
 num-traits = "0.2.11"
 hex-literal = "0.3.4"
 tiny-keccak = { version = "2.0.2", features = ["keccak"] }

utils/src/merkle_tree/full_merkle_tree.rs

@@ -0,0 +1,289 @@
+use crate::merkle_tree::{Hasher, ZerokitMerkleProof, ZerokitMerkleTree};
+use color_eyre::{Report, Result};
+use std::{
+    cmp::max,
+    fmt::Debug,
+    iter::{once, repeat, successors},
+};
+
+////////////////////////////////////////////////////////////
+/// Full Merkle Tree Implementation
+////////////////////////////////////////////////////////////
+
+/// Merkle tree with all leaf and intermediate hashes stored
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct FullMerkleTree<H: Hasher> {
+    /// The depth of the tree, i.e. the number of levels from leaf to root
+    depth: usize,
+
+    /// The nodes cached from the empty part of the tree (where leaves are set to default).
+    /// Since the rightmost part of the tree is usually changed much later than its creation,
+    /// we can prove accumulation of elements in the leftmost part, with no need to initialize the full tree
+    /// and by caching few intermediate nodes to the root computed from default leaves
+    cached_nodes: Vec<H::Fr>,
+
+    /// The tree nodes
+    nodes: Vec<H::Fr>,
+
+    // The next available (i.e., never used) tree index. Equivalently, the number of leaves added to the tree
+    // (deletions leave next_index unchanged)
+    next_index: usize,
+}
+
+/// Element of a Merkle proof
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub enum FullMerkleBranch<H: Hasher> {
+    /// Left branch taken, value is the right sibling hash.
+    Left(H::Fr),
+
+    /// Right branch taken, value is the left sibling hash.
+    Right(H::Fr),
+}
+
+/// Merkle proof path, bottom to top.
+#[derive(Clone, PartialEq, Eq)]
+pub struct FullMerkleProof<H: Hasher>(pub Vec<FullMerkleBranch<H>>);
+
+/// Implementations
+
+impl<H: Hasher> ZerokitMerkleTree<H> for FullMerkleTree<H> {
+    type Proof = FullMerkleProof<H>;
+    fn default(depth: usize) -> Self {
+        FullMerkleTree::<H>::new(depth, H::default_leaf())
+    }
+
+    /// Creates a new `MerkleTree`
+    /// depth - the height of the tree made only of hash nodes. 2^depth is the maximum number of leaves hash nodes
+    fn new(depth: usize, initial_leaf: H::Fr) -> Self {
+        // Compute cache node values, leaf to root
+        let cached_nodes = successors(Some(initial_leaf), |prev| Some(H::hash(&[*prev, *prev])))
+            .take(depth + 1)
+            .collect::<Vec<_>>();
+
+        // Compute node values
+        let nodes = cached_nodes
+            .iter()
+            .rev()
+            .enumerate()
+            .flat_map(|(levels, hash)| repeat(hash).take(1 << levels))
+            .cloned()
+            .collect::<Vec<_>>();
+        debug_assert!(nodes.len() == (1 << (depth + 1)) - 1);
+
+        let next_index = 0;
+
+        Self {
+            depth,
+            cached_nodes,
+            nodes,
+            next_index,
+        }
+    }
+
+    // Returns the depth of the tree
+    fn depth(&self) -> usize {
+        self.depth
+    }
+
+    // Returns the capacity of the tree, i.e. the maximum number of accumulatable leaves
+    fn capacity(&self) -> usize {
+        1 << self.depth
+    }
+
+    // Returns the total number of leaves set
+    fn leaves_set(&mut self) -> usize {
+        self.next_index
+    }
+
+    #[must_use]
+    // Returns the root of the tree
+    fn root(&self) -> H::Fr {
+        self.nodes[0]
+    }
+
+    // Sets a leaf at the specified tree index
+    fn set(&mut self, leaf: usize, hash: H::Fr) -> Result<()> {
+        self.set_range(leaf, once(hash))?;
+        self.next_index = max(self.next_index, leaf + 1);
+        Ok(())
+    }
+
+    // Sets tree nodes, starting from start index
+    // Function proper of FullMerkleTree implementation
+    fn set_range<I: IntoIterator<Item = H::Fr>>(&mut self, start: usize, hashes: I) -> Result<()> {
+        let index = self.capacity() + start - 1;
+        let mut count = 0;
+        // first count number of hashes, and check that they fit in the tree
+        // then insert into the tree
+        let hashes = hashes.into_iter().collect::<Vec<_>>();
+        if hashes.len() + start > self.capacity() {
+            return Err(Report::msg("provided hashes do not fit in the tree"));
+        }
+        hashes.into_iter().for_each(|hash| {
+            self.nodes[index + count] = hash;
+            count += 1;
+        });
+        if count != 0 {
+            self.update_nodes(index, index + (count - 1))?;
+            self.next_index = max(self.next_index, start + count);
+        }
+        Ok(())
+    }
+
+    // Sets a leaf at the next available index
+    fn update_next(&mut self, leaf: H::Fr) -> Result<()> {
+        self.set(self.next_index, leaf)?;
+        Ok(())
+    }
+
+    // Deletes a leaf at a certain index by setting it to its default value (next_index is not updated)
+    fn delete(&mut self, index: usize) -> Result<()> {
+        // We reset the leaf only if we previously set a leaf at that index
+        if index < self.next_index {
+            self.set(index, H::default_leaf())?;
+        }
+        Ok(())
+    }
+
+    // Computes a merkle proof the the leaf at the specified index
+    fn proof(&self, leaf: usize) -> Result<FullMerkleProof<H>> {
+        if leaf >= self.capacity() {
+            return Err(Report::msg("index exceeds set size"));
+        }
+        let mut index = self.capacity() + leaf - 1;
+        let mut path = Vec::with_capacity(self.depth + 1);
+        while let Some(parent) = self.parent(index) {
+            // Add proof for node at index to parent
+            path.push(match index & 1 {
+                1 => FullMerkleBranch::Left(self.nodes[index + 1]),
+                0 => FullMerkleBranch::Right(self.nodes[index - 1]),
+                _ => unreachable!(),
+            });
+            index = parent;
+        }
+        Ok(FullMerkleProof(path))
+    }
+
+    // Verifies a Merkle proof with respect to the input leaf and the tree root
+    fn verify(&self, hash: &H::Fr, proof: &FullMerkleProof<H>) -> Result<bool> {
+        Ok(proof.compute_root_from(hash) == self.root())
+    }
+}
+
+impl<H: Hasher> FullMerkleTree<H>
+where
+    H: Hasher,
+{
+    // Utilities for updating the tree nodes
+
+    /// For a given node index, return the parent node index
+    /// Returns None if there is no parent (root node)
+    fn parent(&self, index: usize) -> Option<usize> {
+        if index == 0 {
+            None
+        } else {
+            Some(((index + 1) >> 1) - 1)
+        }
+    }
+
+    /// For a given node index, return index of the first (left) child.
+    fn first_child(&self, index: usize) -> usize {
+        (index << 1) + 1
+    }
+
+    fn levels(&self, index: usize) -> usize {
+        // `n.next_power_of_two()` will return `n` iff `n` is a power of two.
+        // The extra offset corrects this.
+        (index + 2).next_power_of_two().trailing_zeros() as usize - 1
+    }
+
+    fn update_nodes(&mut self, start: usize, end: usize) -> Result<()> {
+        if self.levels(start) != self.levels(end) {
+            return Err(Report::msg("self.levels(start) != self.levels(end)"));
+        }
+        if let (Some(start), Some(end)) = (self.parent(start), self.parent(end)) {
+            for parent in start..=end {
+                let child = self.first_child(parent);
+                self.nodes[parent] = H::hash(&[self.nodes[child], self.nodes[child + 1]]);
+            }
+            self.update_nodes(start, end)?;
+        }
+        Ok(())
+    }
+}
+
+impl<H: Hasher> ZerokitMerkleProof<H> for FullMerkleProof<H> {
+    type Index = u8;
+
+    #[must_use]
+    // Returns the length of a Merkle proof
+    fn length(&self) -> usize {
+        self.0.len()
+    }
+
+    /// Computes the leaf index corresponding to a Merkle proof
+    #[must_use]
+    fn leaf_index(&self) -> usize {
+        self.0.iter().rev().fold(0, |index, branch| match branch {
+            FullMerkleBranch::Left(_) => index << 1,
+            FullMerkleBranch::Right(_) => (index << 1) + 1,
+        })
+    }
+
+    #[must_use]
+    /// Returns the path elements forming a Merkle proof
+    fn get_path_elements(&self) -> Vec<H::Fr> {
+        self.0
+            .iter()
+            .map(|x| match x {
+                FullMerkleBranch::Left(value) | FullMerkleBranch::Right(value) => *value,
+            })
+            .collect()
+    }
+
+    /// Returns the path indexes forming a Merkle proof
+    #[must_use]
+    fn get_path_index(&self) -> Vec<Self::Index> {
+        self.0
+            .iter()
+            .map(|branch| match branch {
+                FullMerkleBranch::Left(_) => 0,
+                FullMerkleBranch::Right(_) => 1,
+            })
+            .collect()
+    }
+
+    /// Computes the Merkle root corresponding by iteratively hashing a Merkle proof with a given input leaf
+    #[must_use]
+    fn compute_root_from(&self, hash: &H::Fr) -> H::Fr {
+        self.0.iter().fold(*hash, |hash, branch| match branch {
+            FullMerkleBranch::Left(sibling) => H::hash(&[hash, *sibling]),
+            FullMerkleBranch::Right(sibling) => H::hash(&[*sibling, hash]),
+        })
+    }
+}
+
+// Debug formatting for printing a (Full) Merkle Proof Branch
+impl<H> Debug for FullMerkleBranch<H>
+where
+    H: Hasher,
+    H::Fr: Debug,
+{
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Left(arg0) => f.debug_tuple("Left").field(arg0).finish(),
+            Self::Right(arg0) => f.debug_tuple("Right").field(arg0).finish(),
+        }
+    }
+}
+
+// Debug formatting for printing a (Full) Merkle Proof
+impl<H> Debug for FullMerkleProof<H>
+where
+    H: Hasher,
+    H::Fr: Debug,
+{
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_tuple("Proof").field(&self.0).finish()
+    }
+}

utils/src/merkle_tree/merkle_tree.rs

@@ -13,21 +13,13 @@
 //! * Disk based storage backend (using mmaped files should be easy)
 //! * Implement serialization for tree and Merkle proof
 
-#![allow(dead_code)]
-
-use std::collections::HashMap;
-use std::io;
-use std::{
-    cmp::max,
-    fmt::Debug,
-    iter::{once, repeat, successors},
-};
+use color_eyre::Result;
 
 /// In the Hasher trait we define the node type, the default leaf
 /// and the hash function used to initialize a Merkle Tree implementation
 pub trait Hasher {
     /// Type of the leaf and tree node
-    type Fr: Copy + Clone + Eq;
+    type Fr: Clone + Copy + Eq;
 
     /// Returns the default tree leaf
     fn default_leaf() -> Self::Fr;
@@ -36,539 +28,39 @@ pub trait Hasher {
     fn hash(input: &[Self::Fr]) -> Self::Fr;
 }
 
-////////////////////////////////////////////////////////////
-/// Optimal Merkle Tree Implementation
-////////////////////////////////////////////////////////////
-
-/// The Merkle tree structure
-#[derive(Clone, PartialEq, Eq, Debug)]
-pub struct OptimalMerkleTree<H>
+/// In the ZerokitMerkleTree trait we define the methods that are required to be implemented by a Merkle tree
+/// Including, OptimalMerkleTree, FullMerkleTree, Pmtree
+pub trait ZerokitMerkleTree<H: Hasher>
 where
     H: Hasher,
 {
-    /// The depth of the tree, i.e. the number of levels from leaf to root
-    depth: usize,
+    type Proof;
 
-    /// The nodes cached from the empty part of the tree (where leaves are set to default).
-    /// Since the rightmost part of the tree is usually changed much later than its creation,
-    /// we can prove accumulation of elements in the leftmost part, with no need to initialize the full tree
-    /// and by caching few intermediate nodes to the root computed from default leaves
-    cached_nodes: Vec<H::Fr>,
-
-    /// The tree nodes
-    nodes: HashMap<(usize, usize), H::Fr>,
-
-    // The next available (i.e., never used) tree index. Equivalently, the number of leaves added to the tree
-    // (deletions leave next_index unchanged)
-    next_index: usize,
+    fn default(depth: usize) -> Self;
+    fn new(depth: usize, default_leaf: H::Fr) -> Self;
+    fn depth(&self) -> usize;
+    fn capacity(&self) -> usize;
+    fn leaves_set(&mut self) -> usize;
+    fn root(&self) -> H::Fr;
+    fn set(&mut self, index: usize, leaf: H::Fr) -> Result<()>;
+    fn set_range<I>(&mut self, start: usize, leaves: I) -> Result<()>
+    where
+        I: IntoIterator<Item = H::Fr>;
+    fn update_next(&mut self, leaf: H::Fr) -> Result<()>;
+    fn delete(&mut self, index: usize) -> Result<()>;
+    fn proof(&self, index: usize) -> Result<Self::Proof>;
+    fn verify(&self, leaf: &H::Fr, witness: &Self::Proof) -> Result<bool>;
 }
 
-/// The Merkle proof
-/// Contains a vector of (node, branch_index) that defines the proof path elements and branch direction (1 or 0)
-#[derive(Clone, PartialEq, Eq)]
-pub struct OptimalMerkleProof<H: Hasher>(pub Vec<(H::Fr, u8)>);
-
-/// Implementations
-
-impl<H: Hasher> OptimalMerkleTree<H> {
-    pub fn default(depth: usize) -> Self {
-        OptimalMerkleTree::<H>::new(depth, H::default_leaf())
-    }
-
-    /// Creates a new `MerkleTree`
-    /// depth - the height of the tree made only of hash nodes. 2^depth is the maximum number of leaves hash nodes
-    pub fn new(depth: usize, default_leaf: H::Fr) -> Self {
-        let mut cached_nodes: Vec<H::Fr> = Vec::with_capacity(depth + 1);
-        cached_nodes.push(default_leaf);
-        for i in 0..depth {
-            cached_nodes.push(H::hash(&[cached_nodes[i]; 2]));
-        }
-        cached_nodes.reverse();
-        OptimalMerkleTree {
-            cached_nodes: cached_nodes.clone(),
-            depth: depth,
-            nodes: HashMap::new(),
-            next_index: 0,
-        }
-    }
-
-    // Returns the depth of the tree
-    pub fn depth(&self) -> usize {
-        self.depth
-    }
-
-    // Returns the capacity of the tree, i.e. the maximum number of accumulatable leaves
-    pub fn capacity(&self) -> usize {
-        1 << self.depth
-    }
-
-    // Returns the total number of leaves set
-    pub fn leaves_set(&mut self) -> usize {
-        self.next_index
-    }
-
-    #[must_use]
-    // Returns the root of the tree
-    pub fn root(&self) -> H::Fr {
-        self.get_node(0, 0)
-    }
-
-    // Sets a leaf at the specified tree index
-    pub fn set(&mut self, index: usize, leaf: H::Fr) -> io::Result<()> {
-        if index >= self.capacity() {
-            return Err(io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "index exceeds set size",
-            ));
-        }
-        self.nodes.insert((self.depth, index), leaf);
-        self.recalculate_from(index);
-        self.next_index = max(self.next_index, index + 1);
-        Ok(())
-    }
-
-    // Sets multiple leaves from the specified tree index
-    pub fn set_range<I: IntoIterator<Item = H::Fr>>(
-        &mut self,
-        start: usize,
-        leaves: I,
-    ) -> io::Result<()> {
-        let leaves = leaves.into_iter().collect::<Vec<_>>();
-        // check if the range is valid
-        if start + leaves.len() > self.capacity() {
-            return Err(io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "provided range exceeds set size",
-            ));
-        }
-        for (i, leaf) in leaves.iter().enumerate() {
-            self.nodes.insert((self.depth, start + i), *leaf);
-            self.recalculate_from(start + i);
-        }
-        self.next_index = max(self.next_index, start + leaves.len());
-        Ok(())
-    }
-
-    // Sets a leaf at the next available index
-    pub fn update_next(&mut self, leaf: H::Fr) -> io::Result<()> {
-        self.set(self.next_index, leaf)?;
-        Ok(())
-    }
-
-    // Deletes a leaf at a certain index by setting it to its default value (next_index is not updated)
-    pub fn delete(&mut self, index: usize) -> io::Result<()> {
-        // We reset the leaf only if we previously set a leaf at that index
-        if index < self.next_index {
-            self.set(index, H::default_leaf())?;
-        }
-        Ok(())
-    }
-
-    // Computes a merkle proof the the leaf at the specified index
-    pub fn proof(&self, index: usize) -> io::Result<OptimalMerkleProof<H>> {
-        if index >= self.capacity() {
-            return Err(io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "index exceeds set size",
-            ));
-        }
-        let mut witness = Vec::<(H::Fr, u8)>::with_capacity(self.depth);
-        let mut i = index;
-        let mut depth = self.depth;
-        loop {
-            i ^= 1;
-            witness.push((self.get_node(depth, i), (1 - (i & 1)).try_into().unwrap()));
-            i >>= 1;
-            depth -= 1;
-            if depth == 0 {
-                break;
-            }
-        }
-        assert_eq!(i, 0);
-        Ok(OptimalMerkleProof(witness))
-    }
-
-    // Verifies a Merkle proof with respect to the input leaf and the tree root
-    pub fn verify(&self, leaf: &H::Fr, witness: &OptimalMerkleProof<H>) -> io::Result<bool> {
-        if witness.length() != self.depth {
-            return Err(io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "witness length doesn't match tree depth",
-            ));
-        }
-        let expected_root = witness.compute_root_from(leaf);
-        Ok(expected_root.eq(&self.root()))
-    }
-
-    // Utilities for updating the tree nodes
-
-    fn get_node(&self, depth: usize, index: usize) -> H::Fr {
-        let node = *self
-            .nodes
-            .get(&(depth, index))
-            .unwrap_or_else(|| &self.cached_nodes[depth]);
-        node
-    }
-
-    fn get_leaf(&self, index: usize) -> H::Fr {
-        self.get_node(self.depth, index)
-    }
-
-    fn hash_couple(&mut self, depth: usize, index: usize) -> H::Fr {
-        let b = index & !1;
-        H::hash(&[self.get_node(depth, b), self.get_node(depth, b + 1)])
-    }
-
-    fn recalculate_from(&mut self, index: usize) {
-        let mut i = index;
-        let mut depth = self.depth;
-        loop {
-            let h = self.hash_couple(depth, i);
-            i >>= 1;
-            depth -= 1;
-            self.nodes.insert((depth, i), h);
-            if depth == 0 {
-                break;
-            }
-        }
-        assert_eq!(depth, 0);
-        assert_eq!(i, 0);
-    }
-}
-
-impl<H: Hasher> OptimalMerkleProof<H> {
-    #[must_use]
-    // Returns the length of a Merkle proof
-    pub fn length(&self) -> usize {
-        self.0.len()
-    }
-
-    /// Computes the leaf index corresponding to a Merkle proof
-    #[must_use]
-    pub fn leaf_index(&self) -> usize {
-        // In current implementation the path indexes in a proof correspond to the binary representation of the leaf index
-        let mut binary_repr = self.get_path_index();
-        binary_repr.reverse();
-        binary_repr
-            .into_iter()
-            .fold(0, |acc, digit| (acc << 1) + usize::from(digit))
-    }
-
-    #[must_use]
-    /// Returns the path elements forming a Merkle proof
-    pub fn get_path_elements(&self) -> Vec<H::Fr> {
-        self.0.iter().map(|x| x.0).collect()
-    }
-
-    /// Returns the path indexes forming a Merkle proof
-    #[must_use]
-    pub fn get_path_index(&self) -> Vec<u8> {
-        self.0.iter().map(|x| x.1).collect()
-    }
-
-    #[must_use]
-    /// Computes the Merkle root corresponding by iteratively hashing a Merkle proof with a given input leaf
-    pub fn compute_root_from(&self, leaf: &H::Fr) -> H::Fr {
-        let mut acc: H::Fr = *leaf;
-        for w in self.0.iter() {
-            if w.1 == 0 {
-                acc = H::hash(&[acc, w.0]);
-            } else {
-                acc = H::hash(&[w.0, acc]);
-            }
-        }
-        acc
-    }
-}
-
-// Debug formatting for printing a (Optimal) Merkle Proof
-impl<H> Debug for OptimalMerkleProof<H>
+pub trait ZerokitMerkleProof<H: Hasher>
 where
     H: Hasher,
-    H::Fr: Debug,
 {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_tuple("Proof").field(&self.0).finish()
-    }
-}
-
-////////////////////////////////////////////////////////////
-/// Full Merkle Tree Implementation
-////////////////////////////////////////////////////////////
-
-/// Merkle tree with all leaf and intermediate hashes stored
-#[derive(Clone, PartialEq, Eq, Debug)]
-pub struct FullMerkleTree<H: Hasher> {
-    /// The depth of the tree, i.e. the number of levels from leaf to root
-    depth: usize,
-
-    /// The nodes cached from the empty part of the tree (where leaves are set to default).
-    /// Since the rightmost part of the tree is usually changed much later than its creation,
-    /// we can prove accumulation of elements in the leftmost part, with no need to initialize the full tree
-    /// and by caching few intermediate nodes to the root computed from default leaves
-    cached_nodes: Vec<H::Fr>,
-
-    /// The tree nodes
-    nodes: Vec<H::Fr>,
-
-    // The next available (i.e., never used) tree index. Equivalently, the number of leaves added to the tree
-    // (deletions leave next_index unchanged)
-    next_index: usize,
-}
-
-/// Element of a Merkle proof
-#[derive(Clone, Copy, PartialEq, Eq)]
-pub enum FullMerkleBranch<H: Hasher> {
-    /// Left branch taken, value is the right sibling hash.
-    Left(H::Fr),
-
-    /// Right branch taken, value is the left sibling hash.
-    Right(H::Fr),
-}
-
-/// Merkle proof path, bottom to top.
-#[derive(Clone, PartialEq, Eq)]
-pub struct FullMerkleProof<H: Hasher>(pub Vec<FullMerkleBranch<H>>);
-
-/// Implementations
-
-impl<H: Hasher> FullMerkleTree<H> {
-    pub fn default(depth: usize) -> Self {
-        FullMerkleTree::<H>::new(depth, H::default_leaf())
-    }
-
-    /// Creates a new `MerkleTree`
-    /// depth - the height of the tree made only of hash nodes. 2^depth is the maximum number of leaves hash nodes
-    pub fn new(depth: usize, initial_leaf: H::Fr) -> Self {
-        // Compute cache node values, leaf to root
-        let cached_nodes = successors(Some(initial_leaf), |prev| Some(H::hash(&[*prev, *prev])))
-            .take(depth + 1)
-            .collect::<Vec<_>>();
-
-        // Compute node values
-        let nodes = cached_nodes
-            .iter()
-            .rev()
-            .enumerate()
-            .flat_map(|(levels, hash)| repeat(hash).take(1 << levels))
-            .cloned()
-            .collect::<Vec<_>>();
-        debug_assert!(nodes.len() == (1 << (depth + 1)) - 1);
-
-        let next_index = 0;
-
-        Self {
-            depth,
-            cached_nodes,
-            nodes,
-            next_index,
-        }
-    }
-
-    // Returns the depth of the tree
-    pub fn depth(&self) -> usize {
-        self.depth
-    }
-
-    // Returns the capacity of the tree, i.e. the maximum number of accumulatable leaves
-    pub fn capacity(&self) -> usize {
-        1 << self.depth
-    }
-
-    // Returns the total number of leaves set
-    pub fn leaves_set(&mut self) -> usize {
-        self.next_index
-    }
-
-    #[must_use]
-    // Returns the root of the tree
-    pub fn root(&self) -> H::Fr {
-        self.nodes[0]
-    }
-
-    // Sets a leaf at the specified tree index
-    pub fn set(&mut self, leaf: usize, hash: H::Fr) -> io::Result<()> {
-        self.set_range(leaf, once(hash))?;
-        self.next_index = max(self.next_index, leaf + 1);
-        Ok(())
-    }
-
-    // Sets tree nodes, starting from start index
-    // Function proper of FullMerkleTree implementation
-    fn set_range<I: IntoIterator<Item = H::Fr>>(
-        &mut self,
-        start: usize,
-        hashes: I,
-    ) -> io::Result<()> {
-        let index = self.capacity() + start - 1;
-        let mut count = 0;
-        // first count number of hashes, and check that they fit in the tree
-        // then insert into the tree
-        let hashes = hashes.into_iter().collect::<Vec<_>>();
-        if hashes.len() + start > self.capacity() {
-            return Err(io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "provided hashes do not fit in the tree",
-            ));
-        }
-        hashes.into_iter().for_each(|hash| {
-            self.nodes[index + count] = hash;
-            count += 1;
-        });
-        if count != 0 {
-            self.update_nodes(index, index + (count - 1));
-            self.next_index = max(self.next_index, start + count);
-        }
-        Ok(())
-    }
-
-    // Sets a leaf at the next available index
-    pub fn update_next(&mut self, leaf: H::Fr) -> io::Result<()> {
-        self.set(self.next_index, leaf)?;
-        Ok(())
-    }
-
-    // Deletes a leaf at a certain index by setting it to its default value (next_index is not updated)
-    pub fn delete(&mut self, index: usize) -> io::Result<()> {
-        // We reset the leaf only if we previously set a leaf at that index
-        if index < self.next_index {
-            self.set(index, H::default_leaf())?;
-        }
-        Ok(())
-    }
-
-    // Computes a merkle proof the the leaf at the specified index
-    pub fn proof(&self, leaf: usize) -> io::Result<FullMerkleProof<H>> {
-        if leaf >= self.capacity() {
-            return Err(io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "index exceeds set size",
-            ));
-        }
-        let mut index = self.capacity() + leaf - 1;
-        let mut path = Vec::with_capacity(self.depth + 1);
-        while let Some(parent) = self.parent(index) {
-            // Add proof for node at index to parent
-            path.push(match index & 1 {
-                1 => FullMerkleBranch::Left(self.nodes[index + 1]),
-                0 => FullMerkleBranch::Right(self.nodes[index - 1]),
-                _ => unreachable!(),
-            });
-            index = parent;
-        }
-        Ok(FullMerkleProof(path))
-    }
-
-    // Verifies a Merkle proof with respect to the input leaf and the tree root
-    pub fn verify(&self, hash: &H::Fr, proof: &FullMerkleProof<H>) -> io::Result<bool> {
-        Ok(proof.compute_root_from(hash) == self.root())
-    }
-
-    // Utilities for updating the tree nodes
-
-    /// For a given node index, return the parent node index
-    /// Returns None if there is no parent (root node)
-    fn parent(&self, index: usize) -> Option<usize> {
-        if index == 0 {
-            None
-        } else {
-            Some(((index + 1) >> 1) - 1)
-        }
-    }
-
-    /// For a given node index, return index of the first (left) child.
-    fn first_child(&self, index: usize) -> usize {
-        (index << 1) + 1
-    }
-
-    fn levels(&self, index: usize) -> usize {
-        // `n.next_power_of_two()` will return `n` iff `n` is a power of two.
-        // The extra offset corrects this.
-        (index + 2).next_power_of_two().trailing_zeros() as usize - 1
-    }
-
-    fn update_nodes(&mut self, start: usize, end: usize) {
-        debug_assert_eq!(self.levels(start), self.levels(end));
-        if let (Some(start), Some(end)) = (self.parent(start), self.parent(end)) {
-            for parent in start..=end {
-                let child = self.first_child(parent);
-                self.nodes[parent] = H::hash(&[self.nodes[child], self.nodes[child + 1]]);
-            }
-            self.update_nodes(start, end);
-        }
-    }
-}
-
-impl<H: Hasher> FullMerkleProof<H> {
-    #[must_use]
-    // Returns the length of a Merkle proof
-    pub fn length(&self) -> usize {
-        self.0.len()
-    }
-
-    /// Computes the leaf index corresponding to a Merkle proof
-    #[must_use]
-    pub fn leaf_index(&self) -> usize {
-        self.0.iter().rev().fold(0, |index, branch| match branch {
-            FullMerkleBranch::Left(_) => index << 1,
-            FullMerkleBranch::Right(_) => (index << 1) + 1,
-        })
-    }
-
-    #[must_use]
-    /// Returns the path elements forming a Merkle proof
-    pub fn get_path_elements(&self) -> Vec<H::Fr> {
-        self.0
-            .iter()
-            .map(|x| match x {
-                FullMerkleBranch::Left(value) | FullMerkleBranch::Right(value) => *value,
-            })
-            .collect()
-    }
-
-    /// Returns the path indexes forming a Merkle proof
-    #[must_use]
-    pub fn get_path_index(&self) -> Vec<u8> {
-        self.0
-            .iter()
-            .map(|branch| match branch {
-                FullMerkleBranch::Left(_) => 0,
-                FullMerkleBranch::Right(_) => 1,
-            })
-            .collect()
-    }
-
-    /// Computes the Merkle root corresponding by iteratively hashing a Merkle proof with a given input leaf
-    #[must_use]
-    pub fn compute_root_from(&self, hash: &H::Fr) -> H::Fr {
-        self.0.iter().fold(*hash, |hash, branch| match branch {
-            FullMerkleBranch::Left(sibling) => H::hash(&[hash, *sibling]),
-            FullMerkleBranch::Right(sibling) => H::hash(&[*sibling, hash]),
-        })
-    }
-}
-
-// Debug formatting for printing a (Full) Merkle Proof Branch
-impl<H> Debug for FullMerkleBranch<H>
-where
-    H: Hasher,
-    H::Fr: Debug,
-{
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Self::Left(arg0) => f.debug_tuple("Left").field(arg0).finish(),
-            Self::Right(arg0) => f.debug_tuple("Right").field(arg0).finish(),
-        }
-    }
-}
-
-// Debug formatting for printing a (Full) Merkle Proof
-impl<H> Debug for FullMerkleProof<H>
-where
-    H: Hasher,
-    H::Fr: Debug,
-{
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_tuple("Proof").field(&self.0).finish()
-    }
+    type Index;
+
+    fn length(&self) -> usize;
+    fn leaf_index(&self) -> usize;
+    fn get_path_elements(&self) -> Vec<H::Fr>;
+    fn get_path_index(&self) -> Vec<Self::Index>;
+    fn compute_root_from(&self, leaf: &H::Fr) -> H::Fr;
 }

utils/src/merkle_tree/mod.rs

@@ -1,2 +1,7 @@
+pub mod full_merkle_tree;
+#[allow(clippy::module_inception)]
 pub mod merkle_tree;
+pub mod optimal_merkle_tree;
+pub use self::full_merkle_tree::*;
 pub use self::merkle_tree::*;
+pub use self::optimal_merkle_tree::*;

utils/src/merkle_tree/optimal_merkle_tree.rs

@@ -0,0 +1,266 @@
+use crate::merkle_tree::{Hasher, ZerokitMerkleProof, ZerokitMerkleTree};
+use color_eyre::{Report, Result};
+use std::collections::HashMap;
+use std::{cmp::max, fmt::Debug};
+
+////////////////////////////////////////////////////////////
+/// Optimal Merkle Tree Implementation
+////////////////////////////////////////////////////////////
+
+/// The Merkle tree structure
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct OptimalMerkleTree<H>
+where
+    H: Hasher,
+{
+    /// The depth of the tree, i.e. the number of levels from leaf to root
+    depth: usize,
+
+    /// The nodes cached from the empty part of the tree (where leaves are set to default).
+    /// Since the rightmost part of the tree is usually changed much later than its creation,
+    /// we can prove accumulation of elements in the leftmost part, with no need to initialize the full tree
+    /// and by caching few intermediate nodes to the root computed from default leaves
+    cached_nodes: Vec<H::Fr>,
+
+    /// The tree nodes
+    nodes: HashMap<(usize, usize), H::Fr>,
+
+    // The next available (i.e., never used) tree index. Equivalently, the number of leaves added to the tree
+    // (deletions leave next_index unchanged)
+    next_index: usize,
+}
+
+/// The Merkle proof
+/// Contains a vector of (node, branch_index) that defines the proof path elements and branch direction (1 or 0)
+#[derive(Clone, PartialEq, Eq)]
+pub struct OptimalMerkleProof<H: Hasher>(pub Vec<(H::Fr, u8)>);
+
+/// Implementations
+
+impl<H: Hasher> ZerokitMerkleTree<H> for OptimalMerkleTree<H>
+where
+    H: Hasher,
+{
+    type Proof = OptimalMerkleProof<H>;
+
+    fn default(depth: usize) -> Self {
+        OptimalMerkleTree::<H>::new(depth, H::default_leaf())
+    }
+
+    /// Creates a new `MerkleTree`
+    /// depth - the height of the tree made only of hash nodes. 2^depth is the maximum number of leaves hash nodes
+    fn new(depth: usize, default_leaf: H::Fr) -> Self {
+        let mut cached_nodes: Vec<H::Fr> = Vec::with_capacity(depth + 1);
+        cached_nodes.push(default_leaf);
+        for i in 0..depth {
+            cached_nodes.push(H::hash(&[cached_nodes[i]; 2]));
+        }
+        cached_nodes.reverse();
+        OptimalMerkleTree {
+            cached_nodes: cached_nodes.clone(),
+            depth,
+            nodes: HashMap::new(),
+            next_index: 0,
+        }
+    }
+
+    // Returns the depth of the tree
+    fn depth(&self) -> usize {
+        self.depth
+    }
+
+    // Returns the capacity of the tree, i.e. the maximum number of accumulatable leaves
+    fn capacity(&self) -> usize {
+        1 << self.depth
+    }
+
+    // Returns the total number of leaves set
+    fn leaves_set(&mut self) -> usize {
+        self.next_index
+    }
+
+    #[must_use]
+    // Returns the root of the tree
+    fn root(&self) -> H::Fr {
+        self.get_node(0, 0)
+    }
+
+    // Sets a leaf at the specified tree index
+    fn set(&mut self, index: usize, leaf: H::Fr) -> Result<()> {
+        if index >= self.capacity() {
+            return Err(Report::msg("index exceeds set size"));
+        }
+        self.nodes.insert((self.depth, index), leaf);
+        self.recalculate_from(index)?;
+        self.next_index = max(self.next_index, index + 1);
+        Ok(())
+    }
+
+    // Sets multiple leaves from the specified tree index
+    fn set_range<I: IntoIterator<Item = H::Fr>>(&mut self, start: usize, leaves: I) -> Result<()> {
+        let leaves = leaves.into_iter().collect::<Vec<_>>();
+        // check if the range is valid
+        if start + leaves.len() > self.capacity() {
+            return Err(Report::msg("provided range exceeds set size"));
+        }
+        for (i, leaf) in leaves.iter().enumerate() {
+            self.nodes.insert((self.depth, start + i), *leaf);
+            self.recalculate_from(start + i)?;
+        }
+        self.next_index = max(self.next_index, start + leaves.len());
+        Ok(())
+    }
+
+    // Sets a leaf at the next available index
+    fn update_next(&mut self, leaf: H::Fr) -> Result<()> {
+        self.set(self.next_index, leaf)?;
+        Ok(())
+    }
+
+    // Deletes a leaf at a certain index by setting it to its default value (next_index is not updated)
+    fn delete(&mut self, index: usize) -> Result<()> {
+        // We reset the leaf only if we previously set a leaf at that index
+        if index < self.next_index {
+            self.set(index, H::default_leaf())?;
+        }
+        Ok(())
+    }
+
+    // Computes a merkle proof the the leaf at the specified index
+    fn proof(&self, index: usize) -> Result<Self::Proof> {
+        if index >= self.capacity() {
+            return Err(Report::msg("index exceeds set size"));
+        }
+        let mut witness = Vec::<(H::Fr, u8)>::with_capacity(self.depth);
+        let mut i = index;
+        let mut depth = self.depth;
+        loop {
+            i ^= 1;
+            witness.push((self.get_node(depth, i), (1 - (i & 1)).try_into().unwrap()));
+            i >>= 1;
+            depth -= 1;
+            if depth == 0 {
+                break;
+            }
+        }
+        if i != 0 {
+            Err(Report::msg("i != 0"))
+        } else {
+            Ok(OptimalMerkleProof(witness))
+        }
+    }
+
+    // Verifies a Merkle proof with respect to the input leaf and the tree root
+    fn verify(&self, leaf: &H::Fr, witness: &Self::Proof) -> Result<bool> {
+        if witness.length() != self.depth {
+            return Err(Report::msg("witness length doesn't match tree depth"));
+        }
+        let expected_root = witness.compute_root_from(leaf);
+        Ok(expected_root.eq(&self.root()))
+    }
+}
+
+impl<H: Hasher> OptimalMerkleTree<H>
+where
+    H: Hasher,
+{
+    // Utilities for updating the tree nodes
+
+    fn get_node(&self, depth: usize, index: usize) -> H::Fr {
+        let node = *self
+            .nodes
+            .get(&(depth, index))
+            .unwrap_or_else(|| &self.cached_nodes[depth]);
+        node
+    }
+
+    pub fn get_leaf(&self, index: usize) -> H::Fr {
+        self.get_node(self.depth, index)
+    }
+
+    fn hash_couple(&mut self, depth: usize, index: usize) -> H::Fr {
+        let b = index & !1;
+        H::hash(&[self.get_node(depth, b), self.get_node(depth, b + 1)])
+    }
+
+    fn recalculate_from(&mut self, index: usize) -> Result<()> {
+        let mut i = index;
+        let mut depth = self.depth;
+        loop {
+            let h = self.hash_couple(depth, i);
+            i >>= 1;
+            depth -= 1;
+            self.nodes.insert((depth, i), h);
+            if depth == 0 {
+                break;
+            }
+        }
+        if depth != 0 {
+            return Err(Report::msg("did not reach the depth"));
+        }
+        if i != 0 {
+            return Err(Report::msg("did not go through all indexes"));
+        }
+        Ok(())
+    }
+}
+
+impl<H: Hasher> ZerokitMerkleProof<H> for OptimalMerkleProof<H>
+where
+    H: Hasher,
+{
+    type Index = u8;
+    #[must_use]
+    // Returns the length of a Merkle proof
+    fn length(&self) -> usize {
+        self.0.len()
+    }
+
+    /// Computes the leaf index corresponding to a Merkle proof
+    #[must_use]
+    fn leaf_index(&self) -> usize {
+        // In current implementation the path indexes in a proof correspond to the binary representation of the leaf index
+        let mut binary_repr = self.get_path_index();
+        binary_repr.reverse();
+        binary_repr
+            .into_iter()
+            .fold(0, |acc, digit| (acc << 1) + usize::from(digit))
+    }
+
+    #[must_use]
+    /// Returns the path elements forming a Merkle proof
+    fn get_path_elements(&self) -> Vec<H::Fr> {
+        self.0.iter().map(|x| x.0).collect()
+    }
+
+    /// Returns the path indexes forming a Merkle proof
+    #[must_use]
+    fn get_path_index(&self) -> Vec<u8> {
+        self.0.iter().map(|x| x.1).collect()
+    }
+
+    #[must_use]
+    /// Computes the Merkle root corresponding by iteratively hashing a Merkle proof with a given input leaf
+    fn compute_root_from(&self, leaf: &H::Fr) -> H::Fr {
+        let mut acc: H::Fr = *leaf;
+        for w in self.0.iter() {
+            if w.1 == 0 {
+                acc = H::hash(&[acc, w.0]);
+            } else {
+                acc = H::hash(&[w.0, acc]);
+            }
+        }
+        acc
+    }
+}
+
+// Debug formatting for printing a (Optimal) Merkle Proof
+impl<H> Debug for OptimalMerkleProof<H>
+where
+    H: Hasher,
+    H::Fr: Debug,
+{
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_tuple("Proof").field(&self.0).finish()
+    }
+}

utils/src/poseidon/poseidon_constants.rs

@@ -11,7 +11,7 @@
 
 #![allow(dead_code)]
 
-use ark_ff::{FpParameters, PrimeField};
+use ark_ff::PrimeField;
 use num_bigint::BigUint;
 
 pub struct PoseidonGrainLFSR {
@@ -88,8 +88,8 @@ impl PoseidonGrainLFSR {
         }
 
         // b50, ..., b79 are set to 1
-        for i in 50..=79 {
-            state[i] = true;
+        for item in state.iter_mut().skip(50) {
+            *item = true;
         }
 
         let head = 0;
@@ -111,7 +111,7 @@ impl PoseidonGrainLFSR {
             let mut new_bit = self.update();
 
             // Loop until the first bit is true
-            while new_bit == false {
+            while !new_bit {
                 // Discard the second bit
                 let _ = self.update();
                 // Obtain another first bit
@@ -129,8 +129,8 @@ impl PoseidonGrainLFSR {
         &mut self,
         num_elems: usize,
     ) -> Vec<F> {
-        assert_eq!(F::Params::MODULUS_BITS as u64, self.prime_num_bits);
-        let modulus: BigUint = F::Params::MODULUS.into();
+        assert_eq!(F::MODULUS_BIT_SIZE as u64, self.prime_num_bits);
+        let modulus: BigUint = F::MODULUS.into();
 
         let mut res = Vec::new();
         for _ in 0..num_elems {
@@ -163,7 +163,7 @@ impl PoseidonGrainLFSR {
     }
 
     pub fn get_field_elements_mod_p<F: PrimeField>(&mut self, num_elems: usize) -> Vec<F> {
-        assert_eq!(F::Params::MODULUS_BITS as u64, self.prime_num_bits);
+        assert_eq!(F::MODULUS_BIT_SIZE as u64, self.prime_num_bits);
 
         let mut res = Vec::new();
         for _ in 0..num_elems {
@@ -263,8 +263,8 @@ pub fn find_poseidon_ark_and_mds<F: PrimeField>(
     let ys = lfsr.get_field_elements_mod_p::<F>(rate);
 
     for i in 0..(rate) {
-        for j in 0..(rate) {
-            mds[i][j] = (xs[i] + &ys[j]).inverse().unwrap();
+        for (j, ys_item) in ys.iter().enumerate().take(rate) {
+            mds[i][j] = (xs[i] + ys_item).inverse().unwrap();
         }
     }
 

utils/src/poseidon/poseidon_hash.rs

@@ -4,7 +4,7 @@
 // and adapted to work over arkworks field traits and custom data structures
 
 use crate::poseidon_constants::find_poseidon_ark_and_mds;
-use ark_ff::{FpParameters, PrimeField};
+use ark_ff::PrimeField;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct RoundParamenters<F: PrimeField> {
@@ -28,22 +28,21 @@ impl<F: PrimeField> Poseidon<F> {
     pub fn from(poseidon_params: &[(usize, usize, usize, usize)]) -> Self {
         let mut read_params = Vec::<RoundParamenters<F>>::new();
 
-        for i in 0..poseidon_params.len() {
-            let (t, n_rounds_f, n_rounds_p, skip_matrices) = poseidon_params[i];
+        for &(t, n_rounds_f, n_rounds_p, skip_matrices) in poseidon_params {
             let (ark, mds) = find_poseidon_ark_and_mds::<F>(
                 1, // is_field = 1
                 0, // is_sbox_inverse = 0
-                F::Params::MODULUS_BITS as u64,
+                F::MODULUS_BIT_SIZE as u64,
                 t,
                 n_rounds_f as u64,
                 n_rounds_p as u64,
                 skip_matrices,
             );
             let rp = RoundParamenters {
-                t: t,
-                n_rounds_p: n_rounds_p,
-                n_rounds_f: n_rounds_f,
-                skip_matrices: skip_matrices,
+                t,
+                n_rounds_p,
+                n_rounds_f,
+                skip_matrices,
                 c: ark,
                 m: mds,
             };
@@ -67,11 +66,11 @@ impl<F: PrimeField> Poseidon<F> {
 
     pub fn sbox(&self, n_rounds_f: usize, n_rounds_p: usize, state: &mut [F], i: usize) {
         if (i < n_rounds_f / 2) || (i >= n_rounds_f / 2 + n_rounds_p) {
-            for j in 0..state.len() {
-                let aux = state[j];
-                state[j] *= state[j];
-                state[j] *= state[j];
-                state[j] *= aux;
+            for current_state in &mut state.iter_mut() {
+                let aux = *current_state;
+                *current_state *= *current_state;
+                *current_state *= *current_state;
+                *current_state *= aux;
             }
         } else {
             let aux = state[0];
@@ -85,9 +84,9 @@ impl<F: PrimeField> Poseidon<F> {
         let mut new_state: Vec<F> = Vec::new();
         for i in 0..state.len() {
             new_state.push(F::zero());
-            for j in 0..state.len() {
+            for (j, state_item) in state.iter().enumerate() {
                 let mut mij = m[i][j];
-                mij *= state[j];
+                mij *= state_item;
                 new_state[i] += mij;
             }
         }
@@ -116,7 +115,7 @@ impl<F: PrimeField> Poseidon<F> {
             self.ark(
                 &mut state,
                 &self.round_params[param_index].c,
-                (i as usize) * self.round_params[param_index].t,
+                i * self.round_params[param_index].t,
             );
             self.sbox(
                 self.round_params[param_index].n_rounds_f,

utils/tests/merkle_tree.rs

@@ -3,7 +3,7 @@
 mod test {
     use hex_literal::hex;
     use tiny_keccak::{Hasher as _, Keccak};
-    use utils::{FullMerkleTree, Hasher, OptimalMerkleTree};
+    use utils::{FullMerkleTree, Hasher, OptimalMerkleTree, ZerokitMerkleProof, ZerokitMerkleTree};
 
     struct Keccak256;