starkom-plonk 2.0.0

The PLONK arithmetization scheme used in Starkom.
Documentation 
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use primitive_types::H512;
use sha3::Digest;
use starkom_bluesky::Scalar;
use starkom_ff::Field256;

/// Hashes an arbitrary text string into a uniformly distributed BlueSky scalar.
///
/// Under the hood this function works by hashing the string with SHA3-512 and converting the
/// resulting 64 bytes to a BlueSky scalar via modular reduction.
pub(crate) fn hash_to_scalar(message: &[u8]) -> Scalar {
    let mut hasher = sha3::Sha3_512::new();
    hasher.update(message);
    Scalar::from_h512(H512::from_slice(hasher.finalize().as_slice()))
}

#[cfg(test)]
mod tests {
    use super::*;

    fn parse_scalar(s: &'static str) -> Scalar {
        s.parse().unwrap()
    }

    #[test]
    fn test_hash_to_scalar() {
        assert_eq!(
            hash_to_scalar(b"lorem ipsum dolor sit amet"),
            parse_scalar("0x69c562c4b39c86fc322322c86cfe5be83fbd472c6a38862bdd2f362bfa442ad6")
        );
        assert_eq!(
            hash_to_scalar(b"sator arepo tenet opera rotas"),
            parse_scalar("0x027880d47636bf77d55804a6cf2d5ec8f09427cdf678e2ed3d74c432cc2efa7a")
        );
    }
}