sigma-protocols 0.5.1

SIGMA zero-knowledge proof protocols
Documentation 
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use curve25519_dalek::constants::RISTRETTO_BASEPOINT_POINT;
use curve25519_dalek::scalar::Scalar;
use rand::rngs::OsRng;
use rand::TryRngCore;
use sigma_protocols::fiat_shamir::FiatShamirTransform;
use sigma_protocols::protocols::schnorr::{SchnorrProof, SchnorrStatement, SchnorrWitness};
use sigma_protocols::sigma::{Challenge, Commitment, Response, ScalarChallenge, SigmaProtocol};

#[test]
fn test_schnorr_interactive() {
    let mut sk_bytes = [0u8; 32];
    OsRng
        .try_fill_bytes(&mut sk_bytes)
        .expect("Failed to generate random bytes");
    let secret_key = Scalar::from_bytes_mod_order(sk_bytes);
    let public_key = secret_key * RISTRETTO_BASEPOINT_POINT;

    let statement = SchnorrStatement { public_key };
    let witness = SchnorrWitness { secret_key };

    let (commitment, state) = SchnorrProof::prover_commit(&statement, &witness);

    let mut challenge_bytes = [0u8; 32];
    OsRng
        .try_fill_bytes(&mut challenge_bytes)
        .expect("Failed to generate random bytes");
    let challenge_scalar = Scalar::from_bytes_mod_order(challenge_bytes);
    let challenge = ScalarChallenge(challenge_scalar);

    let response = SchnorrProof::prover_response(&statement, &witness, &state, &challenge)
        .expect("Failed to generate response");

    let result = SchnorrProof::verifier(&statement, &commitment, &challenge, &response);
    assert!(result.is_ok(), "Proof verification failed");
}

#[test]
fn test_schnorr_non_interactive() {
    let mut sk_bytes = [0u8; 32];
    OsRng
        .try_fill_bytes(&mut sk_bytes)
        .expect("Failed to generate random bytes");
    let secret_key = Scalar::from_bytes_mod_order(sk_bytes);
    let public_key = secret_key * RISTRETTO_BASEPOINT_POINT;

    let statement = SchnorrStatement { public_key };
    let witness = SchnorrWitness { secret_key };

    let (commitment, state) = SchnorrProof::prover_commit(&statement, &witness);

    let mut fs = FiatShamirTransform::new(b"schnorr-proof", b"test-protocol", b"test-session");

    fs.absorb_commitment(&commitment.to_bytes());

    let challenge_bytes = fs.generate_challenge(32);
    let challenge =
        ScalarChallenge::from_bytes(&challenge_bytes).expect("Failed to create challenge");

    let response = SchnorrProof::prover_response(&statement, &witness, &state, &challenge)
        .expect("Failed to generate response");

    let result = SchnorrProof::verifier(&statement, &commitment, &challenge, &response);
    assert!(result.is_ok(), "Non-interactive proof verification failed");

    let mut verifier_fs =
        FiatShamirTransform::new(b"schnorr-proof", b"test-protocol", b"test-session");

    let verify_result = verifier_fs.verify_transcript(
        &commitment.to_bytes(),
        &challenge_bytes,
        &response.to_bytes(),
    );
    assert!(verify_result.is_ok(), "Transcript verification failed");
}

#[test]
fn test_schnorr_invalid_proof() {
    let mut sk_bytes = [0u8; 32];
    OsRng
        .try_fill_bytes(&mut sk_bytes)
        .expect("Failed to generate random bytes");
    let secret_key = Scalar::from_bytes_mod_order(sk_bytes);
    let public_key = secret_key * RISTRETTO_BASEPOINT_POINT;

    let mut ws_bytes = [0u8; 32];
    OsRng
        .try_fill_bytes(&mut ws_bytes)
        .expect("Failed to generate random bytes");
    let wrong_secret = Scalar::from_bytes_mod_order(ws_bytes);

    let statement = SchnorrStatement { public_key };
    let wrong_witness = SchnorrWitness {
        secret_key: wrong_secret,
    };

    let (commitment, state) = SchnorrProof::prover_commit(&statement, &wrong_witness);

    let mut ch_bytes = [0u8; 32];
    OsRng
        .try_fill_bytes(&mut ch_bytes)
        .expect("Failed to generate random bytes");
    let challenge = ScalarChallenge(Scalar::from_bytes_mod_order(ch_bytes));

    let response = SchnorrProof::prover_response(&statement, &wrong_witness, &state, &challenge)
        .expect("Failed to generate response");

    let result = SchnorrProof::verifier(&statement, &commitment, &challenge, &response);
    assert!(result.is_err(), "Invalid proof should not verify");
}