BN254 Pairing

use risc0_zkvm::guest::env;
use substrate_bn::{Fr, G1, G2, Gt, pairing_batch};

fn main() {
    let inp: bn254_core::Inputs = env::read();

    // Decompress points
    let g1 = G1::from_compressed(&inp.g1_compressed)
        .expect("Point on G1 expected");
    let g2 = G2::from_compressed(&inp.g2_compressed)
        .expect("Point on G2 expected");
    
    // Parse scalar factors
    let a_factor = Fr::from_slice(&inp.a)
        .expect("Scalar factor expected");
    let b_factor = Fr::from_slice(&inp.b)
        .expect("Scalar factor expected");

    // Compute batch pairing:
    // e(a·g1, b·g2) · e(g1, -ab·g2)
    let mut pairs = Vec::new();
    pairs.push((g1 * a_factor, g2 * b_factor));
    pairs.push((g1, g2 * (-a_factor * b_factor)));
    let result = pairing_batch(&pairs);

    // Check if result is identity
    env::commit(&(result == Gt::one()));
}

use bn254_methods::{BN254_VERIFY_ELF, BN254_VERIFY_ID};
use risc0_zkvm::{ExecutorEnv, default_prover};

fn main() {
    // g1 and g2 are generators from EIP-197
    let g1_compressed = hex::decode(
        "020000000000000000000000000000000000000000000000000000000000000001"
    ).expect("valid hex");
    
    let g2_compressed = hex::decode(
        "0A04D4BF3239F77CEE7B47C7245E9281B3E9C1182D6381A87BBF81F9F2A6254B\
         731DF569CDA95E060BEE91BA69B3F2D103658A7AEA6B10E5BDC761E5715E7EE4BB"
    ).expect("valid hex");
    
    // Random scalars chosen for demonstration
    let a = hex::decode(
        "9c0d02eaaf8e7e7ad09595ef6e3b896f8915124ba5bef9287f0997557580caeb"
    ).expect("valid hex");
    let b = hex::decode(
        "db6764642f7bb1f415d93fcd5aace586161ec2e4305f0d6fb57dbabf1d141a5b"
    ).expect("valid hex");

    let input = bn254_core::Inputs {
        g1_compressed,
        g2_compressed,
        a,
        b,
    };

    let env = ExecutorEnv::builder()
        .write(&input)
        .unwrap()
        .build()
        .unwrap();

    let receipt = default_prover()
        .prove(env, BN254_VERIFY_ELF)
        .unwrap()
        .receipt;

    receipt.verify(BN254_VERIFY_ID).unwrap();

    let is_one: bool = receipt.journal.decode()
        .expect("Journal should contain a single bool");
    
    println!("Pairing batch should give one; did it? {}", is_one);
}