rc-crypto 0.1.4

Crypto library for the RC X509 platform
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// Copyright 2026-Present Datadog, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::marker::PhantomData;

/// A hash algorithm with a fixed byte length.
#[allow(private_bounds)]
pub trait HashAlgo<const N: usize>: std::fmt::Debug + Send + Sync + Sized + Sealed {
    /// Hash `data`, returning the [`Digest`] computed using this hash
    /// algorithm.
    fn hash(data: &[u8]) -> Digest<N, Self>;
}

/// All impls of the [`HashAlgo`] trait come from `rc-crypto` to ensure the FIPS
/// crypto backend is used.
pub(super) trait Sealed {}

/// An `N`-byte hash digest produced using the `T` hash algorithm.
#[derive(Debug)]
pub struct Digest<const N: usize, T>
where
    T: HashAlgo<N>,
{
    digest: [u8; N],
    _algo: PhantomData<T>,
}

impl<const N: usize, T> Digest<N, T>
where
    T: HashAlgo<N>,
{
    /// Construct a [`Digest`] from a raw byte hash.
    pub(crate) fn from_raw(digest: [u8; N]) -> Self {
        Self {
            digest,
            _algo: PhantomData,
        }
    }

    /// Access the raw hash bytes.
    pub fn as_bytes(&self) -> &[u8] {
        &self.digest
    }

    /// Return a reference to the fixed size backing array.
    pub fn as_array(&self) -> &[u8; N] {
        &self.digest
    }
}

impl<const N: usize, T> Clone for Digest<N, T>
where
    T: HashAlgo<N>,
{
    fn clone(&self) -> Self {
        Self {
            digest: self.digest,
            _algo: self._algo,
        }
    }
}

impl<const N: usize, T> std::hash::Hash for Digest<N, T>
where
    T: HashAlgo<N>,
{
    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
        self.digest.hash(state);
    }
}

impl<const N: usize, T> Eq for Digest<N, T> where T: HashAlgo<N> {}

impl<const N: usize, T> PartialEq for Digest<N, T>
where
    T: HashAlgo<N>,
{
    fn eq(&self, other: &Self) -> bool {
        self.digest == other.digest
    }
}