Circom external inputs (#91)

* circom: add external_inputs

* adapt new external_inputs interface to the FoldingScheme trait and Nova impl

* adapt examples to new FCircuit external_inputs interface

* add state_len & external_inputs_len params to CircomFCircuit

* add examples/circom_full_flow.rs

* merge the params initializer functions, clippy

* circom: move r1cs reading to FCircuit::new instead of each step

* CI/examples: add circom so it can run the circom_full_flow example

examples/circom_full_flow.rs

@@ -0,0 +1,156 @@
+#![allow(non_snake_case)]
+#![allow(non_camel_case_types)]
+#![allow(clippy::upper_case_acronyms)]
+///
+/// This example performs the full flow:
+/// - define the circuit to be folded
+/// - fold the circuit with Nova+CycleFold's IVC
+/// - generate a DeciderEthCircuit final proof
+/// - generate the Solidity contract that verifies the proof
+/// - verify the proof in the EVM
+///
+use ark_bn254::{constraints::GVar, Bn254, Fr, G1Projective as G1};
+
+use ark_groth16::Groth16;
+use ark_grumpkin::{constraints::GVar as GVar2, Projective as G2};
+
+use std::path::PathBuf;
+use std::time::Instant;
+
+use folding_schemes::{
+    commitment::{kzg::KZG, pedersen::Pedersen},
+    folding::nova::{
+        decider_eth::{prepare_calldata, Decider as DeciderEth},
+        Nova,
+    },
+    frontend::{circom::CircomFCircuit, FCircuit},
+    Decider, FoldingScheme,
+};
+use solidity_verifiers::{
+    evm::{compile_solidity, Evm},
+    utils::get_function_selector_for_nova_cyclefold_verifier,
+    verifiers::nova_cyclefold::get_decider_template_for_cyclefold_decider,
+    NovaCycleFoldVerifierKey,
+};
+
+mod utils;
+use utils::init_ivc_and_decider_params;
+
+fn main() {
+    // set the initial state
+    let z_0 = vec![Fr::from(3_u32)];
+
+    // set the external inputs to be used at each step of the IVC, it has length of 10 since this
+    // is the number of steps that we will do
+    let external_inputs = vec![
+        vec![Fr::from(6u32), Fr::from(7u32)],
+        vec![Fr::from(8u32), Fr::from(9u32)],
+        vec![Fr::from(10u32), Fr::from(11u32)],
+        vec![Fr::from(12u32), Fr::from(13u32)],
+        vec![Fr::from(14u32), Fr::from(15u32)],
+        vec![Fr::from(6u32), Fr::from(7u32)],
+        vec![Fr::from(8u32), Fr::from(9u32)],
+        vec![Fr::from(10u32), Fr::from(11u32)],
+        vec![Fr::from(12u32), Fr::from(13u32)],
+        vec![Fr::from(14u32), Fr::from(15u32)],
+    ];
+
+    // initialize the Circom circuit
+    let r1cs_path =
+        PathBuf::from("./folding-schemes/src/frontend/circom/test_folder/external_inputs.r1cs");
+    let wasm_path = PathBuf::from(
+        "./folding-schemes/src/frontend/circom/test_folder/external_inputs_js/external_inputs.wasm",
+    );
+
+    let f_circuit_params = (r1cs_path, wasm_path, 1, 2);
+    let f_circuit = CircomFCircuit::<Fr>::new(f_circuit_params).unwrap();
+
+    let (fs_prover_params, kzg_vk, g16_pk, g16_vk) =
+        init_ivc_and_decider_params::<CircomFCircuit<Fr>>(f_circuit.clone());
+
+    pub type NOVA =
+        Nova<G1, GVar, G2, GVar2, CircomFCircuit<Fr>, KZG<'static, Bn254>, Pedersen<G2>>;
+    pub type DECIDERETH_FCircuit = DeciderEth<
+        G1,
+        GVar,
+        G2,
+        GVar2,
+        CircomFCircuit<Fr>,
+        KZG<'static, Bn254>,
+        Pedersen<G2>,
+        Groth16<Bn254>,
+        NOVA,
+    >;
+
+    // initialize the folding scheme engine, in our case we use Nova
+    let mut nova = NOVA::init(&fs_prover_params, f_circuit.clone(), z_0).unwrap();
+    // run n steps of the folding iteration
+    for (i, external_inputs_at_step) in external_inputs.iter().enumerate() {
+        let start = Instant::now();
+        nova.prove_step(external_inputs_at_step.clone()).unwrap();
+        println!("Nova::prove_step {}: {:?}", i, start.elapsed());
+    }
+
+    let rng = rand::rngs::OsRng;
+    let start = Instant::now();
+    let proof = DECIDERETH_FCircuit::prove(
+        (g16_pk, fs_prover_params.cs_params.clone()),
+        rng,
+        nova.clone(),
+    )
+    .unwrap();
+    println!("generated Decider proof: {:?}", start.elapsed());
+
+    let verified = DECIDERETH_FCircuit::verify(
+        (g16_vk.clone(), kzg_vk.clone()),
+        nova.i,
+        nova.z_0.clone(),
+        nova.z_i.clone(),
+        &nova.U_i,
+        &nova.u_i,
+        &proof,
+    )
+    .unwrap();
+    assert!(verified);
+    println!("Decider proof verification: {}", verified);
+
+    // Now, let's generate the Solidity code that verifies this Decider final proof
+    let function_selector =
+        get_function_selector_for_nova_cyclefold_verifier(nova.z_0.len() * 2 + 1);
+
+    let calldata: Vec<u8> = prepare_calldata(
+        function_selector,
+        nova.i,
+        nova.z_0,
+        nova.z_i,
+        &nova.U_i,
+        &nova.u_i,
+        proof,
+    )
+    .unwrap();
+
+    // prepare the setup params for the solidity verifier
+    let nova_cyclefold_vk = NovaCycleFoldVerifierKey::from((g16_vk, kzg_vk, f_circuit.state_len()));
+
+    // generate the solidity code
+    let decider_solidity_code = get_decider_template_for_cyclefold_decider(nova_cyclefold_vk);
+
+    // verify the proof against the solidity code in the EVM
+    let nova_cyclefold_verifier_bytecode = compile_solidity(&decider_solidity_code, "NovaDecider");
+    let mut evm = Evm::default();
+    let verifier_address = evm.create(nova_cyclefold_verifier_bytecode);
+    let (_, output) = evm.call(verifier_address, calldata.clone());
+    assert_eq!(*output.last().unwrap(), 1);
+
+    // save smart contract and the calldata
+    println!("storing nova-verifier.sol and the calldata into files");
+    use std::fs;
+    fs::write(
+        "./examples/nova-verifier.sol",
+        decider_solidity_code.clone(),
+    )
+    .unwrap();
+    fs::write("./examples/solidity-calldata.calldata", calldata.clone()).unwrap();
+    let s = solidity_verifiers::utils::get_formatted_calldata(calldata.clone());
+    fs::write("./examples/solidity-calldata.inputs", s.join(",\n")).expect("");
+}