sp1-recursion-gnark-ffi 6.0.2

FFI bindings to Gnark for SP1
Documentation 
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use std::{io::Write, path::Path};

use crate::{
    ffi::{prove_groth16_bn254, test_groth16_bn254, verify_groth16_bn254},
    witness::GnarkWitness,
    Groth16Bn254Proof,
};

use anyhow::Result;
use num_bigint::BigUint;
use sha2::{Digest, Sha256};
use sp1_recursion_compiler::{
    constraints::Constraint,
    ir::{Config, Witness},
};

/// A prover that can generate proofs with the Groth16 protocol using bindings to Gnark.
#[derive(Debug, Clone)]
pub struct Groth16Bn254Prover;

impl Groth16Bn254Prover {
    /// Creates a new [Groth16Bn254Prover].
    pub fn new() -> Self {
        Self
    }

    pub fn get_vkey_hash(build_dir: &Path) -> [u8; 32] {
        let vkey_path = build_dir.join("groth16_vk.bin");
        let vk_bin_bytes = std::fs::read(vkey_path).unwrap();
        Sha256::digest(vk_bin_bytes).into()
    }

    /// Executes the prover in testing mode with a circuit definition and witness.
    pub fn test<C: Config>(constraints: Vec<Constraint>, witness: Witness<C>) {
        let serialized = serde_json::to_string(&constraints).unwrap();

        // Write constraints.
        let mut constraints_file = tempfile::NamedTempFile::new().unwrap();
        constraints_file.write_all(serialized.as_bytes()).unwrap();

        // Write witness.
        let mut witness_file = tempfile::NamedTempFile::new().unwrap();
        let gnark_witness = GnarkWitness::new(witness);
        let serialized = serde_json::to_string(&gnark_witness).unwrap();
        witness_file.write_all(serialized.as_bytes()).unwrap();

        test_groth16_bn254(
            witness_file.path().to_str().unwrap(),
            constraints_file.path().to_str().unwrap(),
        )
    }

    /// Generates a Groth16 proof given a witness.
    pub fn prove<C: Config>(&self, witness: Witness<C>, build_dir: &Path) -> Groth16Bn254Proof {
        // Write witness.
        let mut witness_file = tempfile::NamedTempFile::new().unwrap();
        let gnark_witness = GnarkWitness::new(witness);
        let serialized = serde_json::to_string(&gnark_witness).unwrap();
        witness_file.write_all(serialized.as_bytes()).unwrap();

        let mut proof =
            prove_groth16_bn254(build_dir.to_str().unwrap(), witness_file.path().to_str().unwrap());
        proof.groth16_vkey_hash = Self::get_vkey_hash(build_dir);
        proof
    }

    /// Verify a Groth16 proof and verify that the supplied vkey_hash and committed_values_digest
    /// match.
    #[allow(clippy::too_many_arguments)]
    pub fn verify(
        &self,
        proof: &Groth16Bn254Proof,
        vkey_hash: &BigUint,
        committed_values_digest: &BigUint,
        exit_code: &BigUint,
        vk_root: &BigUint,
        proof_nonce: &BigUint,
        build_dir: &Path,
    ) -> Result<()> {
        if proof.groth16_vkey_hash != Self::get_vkey_hash(build_dir) {
            return Err(anyhow::anyhow!(
                "Proof vkey hash does not match circuit vkey hash, it was generated with a different circuit."
            ));
        }
        verify_groth16_bn254(
            build_dir
                .to_str()
                .ok_or_else(|| anyhow::anyhow!("Failed to convert build dir to string"))?,
            &proof.raw_proof,
            &vkey_hash.to_string(),
            &committed_values_digest.to_string(),
            &exit_code.to_string(),
            &vk_root.to_string(),
            &proof_nonce.to_string(),
        )
        .map_err(|e| anyhow::anyhow!("failed to verify proof: {e}"))
    }
}

impl Default for Groth16Bn254Prover {
    fn default() -> Self {
        Self::new()
    }
}