feat: continue_recursive_circuit api (#34)

* feat: `add_step` api

* fix:  error

* fix: `continue_recursive_circuit` API

* fix: typo

examples/toy_bn254.rs

@@ -1,14 +1,10 @@
 use std::{collections::HashMap, env::current_dir, time::Instant};
 
 use nova_scotia::{
-    circom::reader::load_r1cs, create_public_params, create_recursive_circuit, FileLocation, F, S,
+    circom::reader::load_r1cs, continue_recursive_circuit, create_public_params,
+    create_recursive_circuit, FileLocation, F, S,
 };
-use nova_snark::{
-    provider,
-    traits::{circuit::StepCircuit, Group},
-    CompressedSNARK, PublicParams,
-};
-use pasta_curves::group::ff::Field;
+use nova_snark::{provider, CompressedSNARK, PublicParams};
 use serde_json::json;
 
 fn run_test(circuit_filepath: String, witness_gen_filepath: String) {
@@ -58,9 +54,9 @@ fn run_test(circuit_filepath: String, witness_gen_filepath: String) {
 
     println!("Creating a RecursiveSNARK...");
     let start = Instant::now();
-    let recursive_snark = create_recursive_circuit(
-        FileLocation::PathBuf(witness_generator_file),
-        r1cs,
+    let mut recursive_snark = create_recursive_circuit(
+        FileLocation::PathBuf(witness_generator_file.clone()),
+        r1cs.clone(),
         private_inputs,
         start_public_input.to_vec(),
         &pp,
@@ -82,6 +78,11 @@ fn run_test(circuit_filepath: String, witness_gen_filepath: String) {
     );
     assert!(res.is_ok());
 
+    let z_last = res.unwrap().0;
+
+    assert_eq!(z_last[0], F::<G1>::from(20));
+    assert_eq!(z_last[1], F::<G1>::from(70));
+
     // produce a compressed SNARK
     println!("Generating a CompressedSNARK using Spartan with IPA-PC...");
     let start = Instant::now();
@@ -110,6 +111,48 @@ fn run_test(circuit_filepath: String, witness_gen_filepath: String) {
         start.elapsed()
     );
     assert!(res.is_ok());
+
+    // continue recursive circuit by adding 2 further steps
+    println!("Adding steps to our RecursiveSNARK...");
+    let start = Instant::now();
+
+    let iteration_count_continue = 2;
+
+    let mut private_inputs_continue = Vec::new();
+    for i in 0..iteration_count_continue {
+        let mut private_input = HashMap::new();
+        private_input.insert("adder".to_string(), json!(5 + i));
+        private_inputs_continue.push(private_input);
+    }
+
+    let res = continue_recursive_circuit(
+        &mut recursive_snark,
+        z_last,
+        FileLocation::PathBuf(witness_generator_file),
+        r1cs,
+        private_inputs_continue,
+        start_public_input.to_vec(),
+        &pp,
+    );
+    assert!(res.is_ok());
+    println!(
+        "Adding 2 steps to our RecursiveSNARK took {:?}",
+        start.elapsed()
+    );
+
+    // verify the recursive SNARK with the added steps
+    println!("Verifying a RecursiveSNARK...");
+    let start = Instant::now();
+    let res = recursive_snark.verify(&pp, iteration_count + iteration_count_continue, &start_public_input, &z0_secondary);
+    println!(
+        "RecursiveSNARK::verify: {:?}, took {:?}",
+        res,
+        start.elapsed()
+    );
+    assert!(res.is_ok());
+
+    assert_eq!(res.clone().unwrap().0[0], F::<G1>::from(31));
+    assert_eq!(res.unwrap().0[1], F::<G1>::from(115));
 }
 
 fn main() {

src/lib.rs

@@ -309,3 +309,128 @@ where
 
     Ok(recursive_snark)
 }
+
+#[cfg(not(target_family = "wasm"))]
+pub fn continue_recursive_circuit<G1, G2>(
+    recursive_snark: &mut RecursiveSNARK<G1, G2, C1<G1>, C2<G2>>,
+    last_zi: Vec<F<G1>>,
+    witness_generator_file: FileLocation,
+    r1cs: R1CS<F<G1>>,
+    private_inputs: Vec<HashMap<String, Value>>,
+    start_public_input: Vec<F<G1>>,
+    pp: &PublicParams<G1, G2, C1<G1>, C2<G2>>,
+) -> Result<(), std::io::Error>
+where
+    G1: Group<Base = <G2 as Group>::Scalar>,
+    G2: Group<Base = <G1 as Group>::Scalar>,
+{
+    let root = current_dir().unwrap();
+    let witness_generator_output = root.join("circom_witness.wtns");
+
+    let iteration_count = private_inputs.len();
+
+    let mut current_public_input = last_zi
+        .iter()
+        .map(|&x| format!("{:?}", x).strip_prefix("0x").unwrap().to_string())
+        .collect::<Vec<String>>();
+
+    let circuit_secondary = TrivialTestCircuit::default();
+    let z0_secondary = vec![G2::Scalar::ZERO];
+
+    for i in 0..iteration_count {
+        let witness = compute_witness::<G1, G2>(
+            current_public_input.clone(),
+            private_inputs[i].clone(),
+            witness_generator_file.clone(),
+            &witness_generator_output,
+        );
+
+        let circuit = CircomCircuit {
+            r1cs: r1cs.clone(),
+            witness: Some(witness),
+        };
+
+        let current_public_output = circuit.get_public_outputs();
+        current_public_input = current_public_output
+            .iter()
+            .map(|&x| format!("{:?}", x).strip_prefix("0x").unwrap().to_string())
+            .collect();
+
+        let res = recursive_snark.prove_step(
+            pp,
+            &circuit,
+            &circuit_secondary,
+            start_public_input.clone(),
+            z0_secondary.clone(),
+        );
+
+        assert!(res.is_ok());
+    }
+
+    fs::remove_file(witness_generator_output)?;
+
+    Ok(())
+}
+
+#[cfg(target_family = "wasm")]
+pub async fn continue_recursive_circuit<G1, G2>(
+    recursive_snark: &mut RecursiveSNARK<G1, G2, C1<G1>, C2<G2>>,
+    last_zi: Vec<F<G1>>,
+    witness_generator_file: FileLocation,
+    r1cs: R1CS<F<G1>>,
+    private_inputs: Vec<HashMap<String, Value>>,
+    start_public_input: Vec<F<G1>>,
+    pp: &PublicParams<G1, G2, C1<G1>, C2<G2>>,
+) -> Result<(), std::io::Error>
+where
+    G1: Group<Base = <G2 as Group>::Scalar>,
+    G2: Group<Base = <G1 as Group>::Scalar>,
+{
+    let root = current_dir().unwrap();
+    let witness_generator_output = root.join("circom_witness.wtns");
+
+    let iteration_count = private_inputs.len();
+
+    let mut current_public_input = last_zi
+        .iter()
+        .map(|&x| format!("{:?}", x).strip_prefix("0x").unwrap().to_string())
+        .collect::<Vec<String>>();
+
+    let circuit_secondary = TrivialTestCircuit::default();
+    let z0_secondary = vec![G2::Scalar::ZERO];
+
+    for i in 0..iteration_count {
+        let witness = compute_witness::<G1, G2>(
+            current_public_input.clone(),
+            private_inputs[i].clone(),
+            witness_generator_file.clone(),
+            &witness_generator_output,
+        )
+        .await;
+
+        let circuit = CircomCircuit {
+            r1cs: r1cs.clone(),
+            witness: Some(witness),
+        };
+
+        let current_public_output = circuit.get_public_outputs();
+        current_public_input = current_public_output
+            .iter()
+            .map(|&x| format!("{:?}", x).strip_prefix("0x").unwrap().to_string())
+            .collect();
+
+        let res = recursive_snark.prove_step(
+            pp,
+            &circuit,
+            &circuit_secondary,
+            start_public_input.clone(),
+            z0_secondary.clone(),
+        );
+
+        assert!(res.is_ok());
+    }
+
+    fs::remove_file(witness_generator_output)?;
+
+    Ok(())
+}