agglayer-primitives 0.6.0

use serde::{Deserialize, Serialize};
use tiny_keccak::{Hasher as _, Keccak};

use crate::Digest;

/// Hashes the input data using a Keccak hasher with a 256-bit security level.
#[inline]
pub fn keccak256(data: &[u8]) -> Digest {
    let mut hasher = Keccak::v256();
    hasher.update(data);

    let mut output = [0u8; 32];
    hasher.finalize(&mut output);
    Digest(output)
}

/// Hashes the input items using a Keccak hasher with a 256-bit security level.
/// Safety: This function should only be called with fixed-size items to avoid
/// collisions.
#[inline]
pub fn keccak256_combine<I, T>(items: I) -> Digest
where
    I: IntoIterator<Item = T>,
    T: AsRef<[u8]>,
{
    let mut hasher = Keccak::v256();
    for data in items {
        hasher.update(data.as_ref());
    }

    let mut output = [0u8; 32];
    hasher.finalize(&mut output);
    Digest(output)
}

/// A hasher used in constructing a [`super::LocalExitTree`].
pub trait Hasher {
    type Digest;

    /// Hashes two digests into one.
    fn merge(left: &Self::Digest, right: &Self::Digest) -> Self::Digest;
}

/// A Keccak hasher with a 256-bit security level.
#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq)]
pub struct Keccak256Hasher;

impl Hasher for Keccak256Hasher {
    type Digest = Digest;

    #[inline]
    fn merge(left: &Self::Digest, right: &Self::Digest) -> Self::Digest {
        keccak256_combine([left.as_ref(), right.as_ref()])
    }
}