zerokit/rln-wasm-utils/README.md

RLN WASM Utils

The Zerokit RLN WASM Utils Module provides WebAssembly bindings for Rate-Limiting Nullifier RLN cryptographic primitives. This module offers comprehensive functionality for identity generation and hashing needed for RLN applications.

Features

Identity Generation

• Random Identity Generation: Generate cryptographically secure random identities
• Seeded Identity Generation: Generate deterministic identities from seeds
• Extended Identity Generation: Generate extended identities with additional parameters
• Seeded Extended Identity Generation: Generate deterministic extended identities from seeds
• Endianness Support: Both little-endian and big-endian serialization support

Hashing

• Standard Hashing: Hash arbitrary data to field elements
• Poseidon Hashing: Advanced cryptographic hashing using Poseidon hash function
• Endianness Support: Both little-endian and big-endian serialization support

API Reference

Identity Generation Functions

generateMembershipKey(isLittleEndian: boolean): Uint8Array

Generates a random membership key pair (identity secret and commitment).

Inputs:

• isLittleEndian: Boolean indicating endianness for serialization

Outputs: Serialized identity pair as Uint8Array in corresponding endianness

generateExtendedMembershipKey(isLittleEndian: boolean): Uint8Array

Generates an extended membership key with additional parameters.

Inputs:

• isLittleEndian: Boolean indicating endianness for serialization

Outputs: Serialized extended identity tuple as Uint8Array in corresponding endianness

generateSeededMembershipKey(seed: Uint8Array, isLittleEndian: boolean): Uint8Array

Generates a deterministic membership key from a seed.

Inputs:

• seed: Seed data as Uint8Array
• isLittleEndian: Boolean indicating endianness for serialization

Outputs: Serialized identity pair as Uint8Array in corresponding endianness

generateSeededExtendedMembershipKey(seed: Uint8Array, isLittleEndian: boolean): Uint8Array

Generates a deterministic extended membership key from a seed.

Inputs:

• seed: Seed data as Uint8Array
• isLittleEndian: Boolean indicating endianness for serialization

Outputs: Serialized extended identity tuple as Uint8Array in corresponding endianness

Hashing Functions

hash(input: Uint8Array, isLittleEndian: boolean): Uint8Array

Hashes input data to a field element.

Inputs:

• input: Input data as Uint8Array
• isLittleEndian: Boolean indicating endianness for serialization

Outputs: Serialized hash result as Uint8Array in corresponding endianness

poseidonHash(input: Uint8Array, isLittleEndian: boolean): Uint8Array

Computes Poseidon hash of input field elements.

Inputs:

• input: Serialized field elements as Uint8Array (format: length + field elements)
• isLittleEndian: Boolean indicating endianness for serialization

Outputs: Serialized hash result as Uint8Array in corresponding endianness

Usage Examples

JavaScript/TypeScript

import init, { 
  generateMembershipKey, 
  generateSeededMembershipKey,
  hash,
  poseidonHash 
} from '@waku/zerokit-rln-wasm-utils';

// Initialize the WASM module
await init();

// Generate a random membership key
const membershipKey = generateMembershipKey(true); // little-endian
console.log('Membership key:', membershipKey);

// Generate a deterministic membership key from seed
const seed = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
const seededKey = generateSeededMembershipKey(seed, true);
console.log('Seeded key:', seededKey);

// Hash some data
const input = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
const hashResult = hash(input, true);
console.log('Hash result:', hashResult);

// Poseidon hash with field elements
const fieldElements = new Uint8Array([
  // Length (8 bytes) + field elements (32 bytes each)
  1, 0, 0, 0, 0, 0, 0, 0, // length = 1
  // field element data...
]);
const poseidonResult = poseidonHash(fieldElements, true);
console.log('Poseidon hash:', poseidonResult);

Install Dependencies

Note

This project requires the following tools:

• wasm-pack - for compiling Rust to WebAssembly
• cargo-make - for running build commands
• nvm - to install and manage Node.js

Ensure all dependencies are installed before proceeding.

Manually

Install wasm-pack

cargo install wasm-pack --version=0.13.1

Install cargo-make

cargo install cargo-make

Install Node.js

If you don't have nvm (Node Version Manager), install it by following the installation instructions.

After installing nvm, install and use Node.js v22.14.0:

nvm install 22.14.0
nvm use 22.14.0
nvm alias default 22.14.0

If you already have Node.js installed, check your version with node -v command — the version must be strictly greater than 22.

Or install everything

You can run the following command from the root of the repository to install all required dependencies for zerokit

make installdeps

Building the library

First, navigate to the rln-wasm-utils directory:

cd rln-wasm-utils

Compile rln-wasm-utils for wasm32-unknown-unknown:

cargo make build

Running tests

cargo make test

License

This project is licensed under both MIT and Apache 2.0 licenses. See the LICENSE files for details.