Function randomize_proof

saver/src/saver_groth16.rs:109–136

Randomize the Groth16 proof as per algorithm 2 of the paper. Can alternatively use `rerandomize_proof` from `ark_groth16`

(
    mut proof: Proof<E>,
    r_prime: &E::ScalarField,
    vk: &VerifyingKey<E>,
    encryption_key: &EncryptionKey<E>,
    rng: &mut R,
)

/// Randomize the Groth16 proof as per algorithm 2 of the paper. Can alternatively use
/// `rerandomize_proof` from `ark_groth16`
pub fn randomize_proof<E: Pairing, R: Rng>(
    mut proof: Proof<E>,
    r_prime: &E::ScalarField,
    vk: &VerifyingKey<E>,
    encryption_key: &EncryptionKey<E>,
    rng: &mut R,
) -> Result<Proof<E>, SaverError> {
    let (z1, z2) = (
        non_zero_random::<E::ScalarField, R>(rng),
        non_zero_random::<E::ScalarField, R>(rng),
    );
    let z1_inv = z1.inverse().unwrap();
    let z1z2 = z1 * z2;

    // proof.c = proof.c + proof.A * z1z2 + r' * P_2
    let mut c = proof.c.into_group();
    c.add_assign(proof.a.mul_bigint(z1z2.into_bigint()));
    c.add_assign(encryption_key.P_2.mul_bigint(r_prime.into_bigint()));
    proof.c = c.into_affine();

    let mut b = proof.b.mul_bigint(z1_inv.into_bigint());
    b.add_assign(vk.delta_g2.mul(z2));
    proof.b = b.into_affine();

    proof.a = proof.a.mul_bigint(z1.into_bigint()).into_affine();

    Ok(proof)
}

pub fn verify_proof<E: Pairing>(
    pvk: &PreparedVerifyingKey<E>,