krypteia-tessera 0.2.0

// SPDX-License-Identifier: Apache-2.0
// Copyright 2026 Cédric Mesnil <cslashm@pm.me>

//! SHA-2 family (FIPS 180-4): SHA-224/256 (32-bit core) and
//! SHA-384/512/512-224/512-256 (64-bit core), behind the [`Digest`] trait.
//!
//! Ported from arcana's standalone SHA-2 modules into the shared crate.
//!
//! # Side-channel posture
//!
//! As unkeyed hashes these are not SCA-sensitive (no secret input). When
//! consumed by a keyed construction (HMAC, HMAC-DRBG, MGF1 over a secret),
//! the carry-based CDPA of `belenky2023_cdpa_hmac_sha2` applies — a masked
//! variant is roadmap item arcana T2-D, out of scope here.

use crate::Digest;

// ---- SHA-256 / SHA-224 (32-bit core) ---------------------------------------

const H256: [u32; 8] = [
    0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
];
const H224: [u32; 8] = [
    0xc1059ed8, 0x367cd507, 0x3070dd17, 0xf70e5939, 0xffc00b31, 0x68581511, 0x64f98fa7, 0xbefa4fa4,
];

const K256: [u32; 64] = [
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98,
    0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
    0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8,
    0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819,
    0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
    0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7,
    0xc67178f2,
];

fn compress256(state: &mut [u32; 8], block: &[u8]) {
    let mut w = [0u32; 64];
    for i in 0..16 {
        w[i] = u32::from_be_bytes([block[4 * i], block[4 * i + 1], block[4 * i + 2], block[4 * i + 3]]);
    }
    for i in 16..64 {
        let s0 = w[i - 15].rotate_right(7) ^ w[i - 15].rotate_right(18) ^ (w[i - 15] >> 3);
        let s1 = w[i - 2].rotate_right(17) ^ w[i - 2].rotate_right(19) ^ (w[i - 2] >> 10);
        w[i] = w[i - 16].wrapping_add(s0).wrapping_add(w[i - 7]).wrapping_add(s1);
    }
    let mut a = state[0];
    let mut b = state[1];
    let mut c = state[2];
    let mut d = state[3];
    let mut e = state[4];
    let mut f = state[5];
    let mut g = state[6];
    let mut h = state[7];
    for i in 0..64 {
        let s1 = e.rotate_right(6) ^ e.rotate_right(11) ^ e.rotate_right(25);
        let ch = (e & f) ^ ((!e) & g);
        let temp1 = h
            .wrapping_add(s1)
            .wrapping_add(ch)
            .wrapping_add(K256[i])
            .wrapping_add(w[i]);
        let s0 = a.rotate_right(2) ^ a.rotate_right(13) ^ a.rotate_right(22);
        let maj = (a & b) ^ (a & c) ^ (b & c);
        let temp2 = s0.wrapping_add(maj);
        h = g;
        g = f;
        f = e;
        e = d.wrapping_add(temp1);
        d = c;
        c = b;
        b = a;
        a = temp1.wrapping_add(temp2);
    }
    state[0] = state[0].wrapping_add(a);
    state[1] = state[1].wrapping_add(b);
    state[2] = state[2].wrapping_add(c);
    state[3] = state[3].wrapping_add(d);
    state[4] = state[4].wrapping_add(e);
    state[5] = state[5].wrapping_add(f);
    state[6] = state[6].wrapping_add(g);
    state[7] = state[7].wrapping_add(h);
}

macro_rules! sha256_family {
    ($name:ident, $iv:expr, $out:expr, $block:expr, $doc:literal) => {
        #[doc = $doc]
        #[derive(Clone)]
        pub struct $name {
            state: [u32; 8],
            buf: [u8; 64],
            buf_len: usize,
            total_len: u64,
        }

        impl Digest for $name {
            const OUTPUT_LEN: usize = $out;
            const BLOCK_LEN: usize = $block;

            fn new() -> Self {
                Self {
                    state: $iv,
                    buf: [0u8; 64],
                    buf_len: 0,
                    total_len: 0,
                }
            }

            fn update(&mut self, data: &[u8]) {
                let mut pos = 0;
                self.total_len += data.len() as u64;
                if self.buf_len > 0 {
                    let take = (64 - self.buf_len).min(data.len());
                    self.buf[self.buf_len..self.buf_len + take].copy_from_slice(&data[..take]);
                    self.buf_len += take;
                    pos = take;
                    if self.buf_len == 64 {
                        let block = self.buf;
                        compress256(&mut self.state, &block);
                        self.buf_len = 0;
                    }
                }
                while pos + 64 <= data.len() {
                    compress256(&mut self.state, &data[pos..pos + 64]);
                    pos += 64;
                }
                if pos < data.len() {
                    let rem = data.len() - pos;
                    self.buf[..rem].copy_from_slice(&data[pos..]);
                    self.buf_len = rem;
                }
            }

            fn finalize(mut self, out: &mut [u8]) {
                let bit_len = self.total_len * 8;
                let mut pad = [0u8; 72];
                pad[0] = 0x80;
                let pad_len = if self.buf_len < 56 {
                    56 - self.buf_len
                } else {
                    120 - self.buf_len
                };
                self.update(&pad[..pad_len]);
                self.update(&bit_len.to_be_bytes());
                let mut digest = [0u8; 32];
                for (i, word) in self.state.iter().enumerate() {
                    digest[i * 4..i * 4 + 4].copy_from_slice(&word.to_be_bytes());
                }
                out[..$out].copy_from_slice(&digest[..$out]);
            }
        }
    };
}

sha256_family!(Sha256, H256, 32, 64, "SHA-256 (FIPS 180-4).");
sha256_family!(Sha224, H224, 28, 64, "SHA-224 (FIPS 180-4).");

// ---- SHA-512 / SHA-384 / SHA-512-224 / SHA-512-256 (64-bit core) -----------

const H512: [u64; 8] = [
    0x6a09e667f3bcc908,
    0xbb67ae8584caa73b,
    0x3c6ef372fe94f82b,
    0xa54ff53a5f1d36f1,
    0x510e527fade682d1,
    0x9b05688c2b3e6c1f,
    0x1f83d9abfb41bd6b,
    0x5be0cd19137e2179,
];
const H384: [u64; 8] = [
    0xcbbb9d5dc1059ed8,
    0x629a292a367cd507,
    0x9159015a3070dd17,
    0x152fecd8f70e5939,
    0x67332667ffc00b31,
    0x8eb44a8768581511,
    0xdb0c2e0d64f98fa7,
    0x47b5481dbefa4fa4,
];
const H512_224: [u64; 8] = [
    0x8c3d37c819544da2,
    0x73e1996689dcd4d6,
    0x1dfab7ae32ff9c82,
    0x679dd514582f9fcf,
    0x0f6d2b697bd44da8,
    0x77e36f7304c48942,
    0x3f9d85a86a1d36c8,
    0x1112e6ad91d692a1,
];
const H512_256: [u64; 8] = [
    0x22312194fc2bf72c,
    0x9f555fa3c84c64c2,
    0x2393b86b6f53b151,
    0x963877195940eabd,
    0x96283ee2a88effe3,
    0xbe5e1e2553863992,
    0x2b0199fc2c85b8aa,
    0x0eb72ddc81c52ca2,
];

const K512: [u64; 80] = [
    0x428a2f98d728ae22,
    0x7137449123ef65cd,
    0xb5c0fbcfec4d3b2f,
    0xe9b5dba58189dbbc,
    0x3956c25bf348b538,
    0x59f111f1b605d019,
    0x923f82a4af194f9b,
    0xab1c5ed5da6d8118,
    0xd807aa98a3030242,
    0x12835b0145706fbe,
    0x243185be4ee4b28c,
    0x550c7dc3d5ffb4e2,
    0x72be5d74f27b896f,
    0x80deb1fe3b1696b1,
    0x9bdc06a725c71235,
    0xc19bf174cf692694,
    0xe49b69c19ef14ad2,
    0xefbe4786384f25e3,
    0x0fc19dc68b8cd5b5,
    0x240ca1cc77ac9c65,
    0x2de92c6f592b0275,
    0x4a7484aa6ea6e483,
    0x5cb0a9dcbd41fbd4,
    0x76f988da831153b5,
    0x983e5152ee66dfab,
    0xa831c66d2db43210,
    0xb00327c898fb213f,
    0xbf597fc7beef0ee4,
    0xc6e00bf33da88fc2,
    0xd5a79147930aa725,
    0x06ca6351e003826f,
    0x142929670a0e6e70,
    0x27b70a8546d22ffc,
    0x2e1b21385c26c926,
    0x4d2c6dfc5ac42aed,
    0x53380d139d95b3df,
    0x650a73548baf63de,
    0x766a0abb3c77b2a8,
    0x81c2c92e47edaee6,
    0x92722c851482353b,
    0xa2bfe8a14cf10364,
    0xa81a664bbc423001,
    0xc24b8b70d0f89791,
    0xc76c51a30654be30,
    0xd192e819d6ef5218,
    0xd69906245565a910,
    0xf40e35855771202a,
    0x106aa07032bbd1b8,
    0x19a4c116b8d2d0c8,
    0x1e376c085141ab53,
    0x2748774cdf8eeb99,
    0x34b0bcb5e19b48a8,
    0x391c0cb3c5c95a63,
    0x4ed8aa4ae3418acb,
    0x5b9cca4f7763e373,
    0x682e6ff3d6b2b8a3,
    0x748f82ee5defb2fc,
    0x78a5636f43172f60,
    0x84c87814a1f0ab72,
    0x8cc702081a6439ec,
    0x90befffa23631e28,
    0xa4506cebde82bde9,
    0xbef9a3f7b2c67915,
    0xc67178f2e372532b,
    0xca273eceea26619c,
    0xd186b8c721c0c207,
    0xeada7dd6cde0eb1e,
    0xf57d4f7fee6ed178,
    0x06f067aa72176fba,
    0x0a637dc5a2c898a6,
    0x113f9804bef90dae,
    0x1b710b35131c471b,
    0x28db77f523047d84,
    0x32caab7b40c72493,
    0x3c9ebe0a15c9bebc,
    0x431d67c49c100d4c,
    0x4cc5d4becb3e42b6,
    0x597f299cfc657e2a,
    0x5fcb6fab3ad6faec,
    0x6c44198c4a475817,
];

fn compress512(state: &mut [u64; 8], block: &[u8]) {
    let mut w = [0u64; 80];
    for i in 0..16 {
        let mut b = [0u8; 8];
        b.copy_from_slice(&block[8 * i..8 * i + 8]);
        w[i] = u64::from_be_bytes(b);
    }
    for i in 16..80 {
        let s0 = w[i - 15].rotate_right(1) ^ w[i - 15].rotate_right(8) ^ (w[i - 15] >> 7);
        let s1 = w[i - 2].rotate_right(19) ^ w[i - 2].rotate_right(61) ^ (w[i - 2] >> 6);
        w[i] = w[i - 16].wrapping_add(s0).wrapping_add(w[i - 7]).wrapping_add(s1);
    }
    let mut a = state[0];
    let mut b = state[1];
    let mut c = state[2];
    let mut d = state[3];
    let mut e = state[4];
    let mut f = state[5];
    let mut g = state[6];
    let mut h = state[7];
    for i in 0..80 {
        let s1 = e.rotate_right(14) ^ e.rotate_right(18) ^ e.rotate_right(41);
        let ch = (e & f) ^ ((!e) & g);
        let temp1 = h
            .wrapping_add(s1)
            .wrapping_add(ch)
            .wrapping_add(K512[i])
            .wrapping_add(w[i]);
        let s0 = a.rotate_right(28) ^ a.rotate_right(34) ^ a.rotate_right(39);
        let maj = (a & b) ^ (a & c) ^ (b & c);
        let temp2 = s0.wrapping_add(maj);
        h = g;
        g = f;
        f = e;
        e = d.wrapping_add(temp1);
        d = c;
        c = b;
        b = a;
        a = temp1.wrapping_add(temp2);
    }
    state[0] = state[0].wrapping_add(a);
    state[1] = state[1].wrapping_add(b);
    state[2] = state[2].wrapping_add(c);
    state[3] = state[3].wrapping_add(d);
    state[4] = state[4].wrapping_add(e);
    state[5] = state[5].wrapping_add(f);
    state[6] = state[6].wrapping_add(g);
    state[7] = state[7].wrapping_add(h);
}

macro_rules! sha512_family {
    ($name:ident, $iv:expr, $out:expr, $doc:literal) => {
        #[doc = $doc]
        #[derive(Clone)]
        pub struct $name {
            state: [u64; 8],
            buf: [u8; 128],
            buf_len: usize,
            total_len: u128,
        }

        impl Digest for $name {
            const OUTPUT_LEN: usize = $out;
            const BLOCK_LEN: usize = 128;

            fn new() -> Self {
                Self {
                    state: $iv,
                    buf: [0u8; 128],
                    buf_len: 0,
                    total_len: 0,
                }
            }

            fn update(&mut self, data: &[u8]) {
                let mut pos = 0;
                self.total_len += data.len() as u128;
                if self.buf_len > 0 {
                    let take = (128 - self.buf_len).min(data.len());
                    self.buf[self.buf_len..self.buf_len + take].copy_from_slice(&data[..take]);
                    self.buf_len += take;
                    pos = take;
                    if self.buf_len == 128 {
                        let block = self.buf;
                        compress512(&mut self.state, &block);
                        self.buf_len = 0;
                    }
                }
                while pos + 128 <= data.len() {
                    compress512(&mut self.state, &data[pos..pos + 128]);
                    pos += 128;
                }
                if pos < data.len() {
                    let rem = data.len() - pos;
                    self.buf[..rem].copy_from_slice(&data[pos..]);
                    self.buf_len = rem;
                }
            }

            fn finalize(mut self, out: &mut [u8]) {
                let bit_len = self.total_len * 8;
                let mut pad = [0u8; 136];
                pad[0] = 0x80;
                let pad_len = if self.buf_len < 112 {
                    112 - self.buf_len
                } else {
                    240 - self.buf_len
                };
                self.update(&pad[..pad_len]);
                self.update(&bit_len.to_be_bytes());
                let mut digest = [0u8; 64];
                for (i, word) in self.state.iter().enumerate() {
                    digest[i * 8..i * 8 + 8].copy_from_slice(&word.to_be_bytes());
                }
                out[..$out].copy_from_slice(&digest[..$out]);
            }
        }
    };
}

sha512_family!(Sha512, H512, 64, "SHA-512 (FIPS 180-4).");
sha512_family!(Sha384, H384, 48, "SHA-384 (FIPS 180-4).");
sha512_family!(Sha512_224, H512_224, 28, "SHA-512/224 (FIPS 180-4).");
sha512_family!(Sha512_256, H512_256, 32, "SHA-512/256 (FIPS 180-4).");

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

    fn hx(h: &str) -> alloc::vec::Vec<u8> {
        (0..h.len())
            .step_by(2)
            .map(|i| u8::from_str_radix(&h[i..i + 2], 16).unwrap())
            .collect()
    }

    // Smoke KAT: FIPS 180-4 SHA-256("abc"). The full CAVP/ACVP corpora
    // for SHA-1/224/256/384/512 and SHA-512/224/256 live in the
    // integration suites `tests/cavp_shs.rs` and `tests/acvp_hashes.rs`.
    #[test]
    fn sha256_smoke() {
        let mut out = [0u8; 32];
        Sha256::digest(b"abc", &mut out);
        assert_eq!(
            &out[..],
            &hx("ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad")[..]
        );
    }
}