plonky2/src/hash/gmimc.rs

use unroll::unroll_for_loops;

use crate::field::field_types::Field;
use crate::field::goldilocks_field::GoldilocksField;

pub(crate) const NUM_ROUNDS: usize = 101;

pub trait GMiMC<const WIDTH: usize>: Field
where
    [u64; NUM_ROUNDS]: Sized,
{
    const ROUND_CONSTANTS: [u64; NUM_ROUNDS];

    #[unroll_for_loops]
    fn gmimc_permute(mut xs: [Self; WIDTH]) -> [Self; WIDTH] {
        // Value that is implicitly added to each element.
        // See https://affine.group/2020/02/starkware-challenge
        let mut addition_buffer = Self::ZERO;

        for (r, &constant) in Self::ROUND_CONSTANTS.iter().enumerate() {
            let active = r % WIDTH;
            let f = (xs[active] + addition_buffer + Self::from_canonical_u64(constant)).cube();
            addition_buffer += f;
            xs[active] -= f;
        }

        for i in 0..WIDTH {
            xs[i] += addition_buffer;
        }

        xs
    }

    #[unroll_for_loops]
    fn gmimc_permute_naive(mut xs: [Self; WIDTH]) -> [Self; WIDTH] {
        for (r, &constant) in Self::ROUND_CONSTANTS.iter().enumerate() {
            let active = r % WIDTH;
            let f = (xs[active] + Self::from_canonical_u64(constant)).cube();
            for i in 0..WIDTH {
                if i != active {
                    xs[i] += f;
                }
            }
        }

        xs
    }
}

/// See `generate_constants` about how these were generated.
#[rustfmt::skip]
const GOLDILOCKS_ROUND_CONSTANTS: [u64; NUM_ROUNDS] = [
    0xb585f767417ee042, 0x7746a55f77c10331, 0xb2fb0d321d356f7a, 0x0f6760a486f1621f,
    0xe10d6666b36abcdf, 0x8cae14cb455cc50b, 0xd438539cf2cee334, 0xef781c7d4c1fd8b4,
    0xcdc4a23a0aca4b1f, 0x277fa208d07b52e3, 0xe17653a300493d38, 0xc54302f27c287dc1,
    0x8628782231d47d10, 0x59cd1a8a690b49f2, 0xc3b919ad9efec0b0, 0xa484c4c637641d97,
    0x308bbd23f191398b, 0x6e4a40c1bf713cf1, 0x9a2eedb7510414fb, 0xe360c6e111c2c63b,
    0xd5c771901d4d89aa, 0xc35eae076e7d6b2f, 0x849c2656d0a09cad, 0xc0572c8c5cf1df2b,
    0xe9fa634a883b8bf3, 0xf56f6d4900fb1fdd, 0xf7d713e872a72a1b, 0x8297132b6ba47612,
    0xad6805e12ee8af1c, 0xac51d9f6485c22b9, 0x502ad7dc3bd56bf8, 0x57a1550c3761c577,
    0x66bbd30e99d311da, 0x0da2abef5e948f87, 0xf0612750443f8e94, 0x28b8ec3afb937d8c,
    0x92a756e6be54ca18, 0x70e741ec304e925d, 0x019d5ee2b037c59f, 0x6f6f2ed7a30707d1,
    0x7cf416d01e8c169c, 0x61df517bb17617df, 0x85dc499b4c67dbaa, 0x4b959b48dad27b23,
    0xe8be3e5e0dd779a0, 0xf5c0bc1e525ed8e6, 0x40b12cbf263cf853, 0xa637093f13e2ea3c,
    0x3cc3f89232e3b0c8, 0x2e479dc16bfe86c0, 0x6f49de07d6d39469, 0x213ce7beecc232de,
    0x5b043134851fc00a, 0xa2de45784a861506, 0x7103aaf97bed8dd5, 0x5326fc0dbb88a147,
    0xa9ceb750364cb77a, 0x27f8ec88cc9e991f, 0xfceb4fda8c93fb83, 0xfac6ff13b45b260e,
    0x7131aa455813380b, 0x93510360d5d68119, 0xad535b24fb96e3db, 0x4627f5c6b7efc045,
    0x645cf794e4da78a9, 0x241c70ed1ac2877f, 0xacb8e076b009e825, 0x3737e9db6477bd9d,
    0xe7ea5e344cd688ed, 0x90dee4a009214640, 0xd1b1edf7c77e74af, 0x0b65481bab42158e,
    0x99ad1aab4b4fe3e7, 0x438a7c91f1a360cd, 0xb60de3bd159088bf, 0xc99cab6b47a3e3bb,
    0x69a5ed92d5677cef, 0x5e7b329c482a9396, 0x5fc0ac0829f893c9, 0x32db82924fb757ea,
    0x0ade699c5cf24145, 0x7cc5583b46d7b5bb, 0x85df9ed31bf8abcb, 0x6604df501ad4de64,
    0xeb84f60941611aec, 0xda60883523989bd4, 0x8f97fe40bf3470bf, 0xa93f485ce0ff2b32,
    0x6704e8eebc2afb4b, 0xcee3e9ac788ad755, 0x510d0e66062a270d, 0xf6323f48d74634a0,
    0x0b508cdf04990c90, 0xf241708a4ef7ddf9, 0x60e75c28bb368f82, 0xa6217d8c3f0f9989,
    0x7159cd30f5435b53, 0x839b4e8fe97ec79f, 0x0d3f3e5e885db625, 0x8f7d83be1daea54b,
    0x780f22441e8dbc04,
];

impl GMiMC<8> for GoldilocksField {
    const ROUND_CONSTANTS: [u64; NUM_ROUNDS] = GOLDILOCKS_ROUND_CONSTANTS;
}

impl GMiMC<12> for GoldilocksField {
    const ROUND_CONSTANTS: [u64; NUM_ROUNDS] = GOLDILOCKS_ROUND_CONSTANTS;
}

#[cfg(test)]
mod tests {
    use crate::field::goldilocks_field::GoldilocksField;
    use crate::hash::gmimc::GMiMC;

    fn check_consistency<F: GMiMC<WIDTH>, const WIDTH: usize>() {
        let xs = F::rand_arr::<WIDTH>();
        let out = F::gmimc_permute(xs);
        let out_naive = F::gmimc_permute_naive(xs);
        assert_eq!(out, out_naive);
    }

    #[test]
    fn consistency() {
        check_consistency::<GoldilocksField, 12>();
    }
}