courierust 1.0.0

//! Incremental SHA-256 / SHA-384 digests (FIPS 180-4) with a shared
//! [`Digest`] trait.
//!
//! TLS 1.3 needs a running transcript hash across the handshake, so a
//! one-shot function is not enough: the transcript is fed incrementally
//! as messages arrive. Both hashes share the same block logic with
//! different constants/output sizes; SHA-384 also differs in the 128-bit
//! length field and the initial chaining values.

use core::fmt;

/// Message-digest interface used by the TLS transcript and signatures.
pub trait Digest {
    /// Feed `data` into the running hash.
    fn update(&mut self, data: &[u8]);
    /// Finalize and return the digest (resets the state for reuse).
    fn finalize(&mut self) -> Vec<u8>;
    /// Length of the produced digest in bytes.
    fn output_len(&self) -> usize;
    /// The block size in bytes (used by HMAC).
    fn block_len(&self) -> usize;
    /// Return a copy of this hasher with the same running state. The
    /// TLS transcript hashes a growing message log without disturbing
    /// it, so we fork a snapshot and finalize that.
    fn fork(&self) -> BoxDigest;
}

/// A boxed digest for trait-object use (the TLS layer switches between
/// SHA-256 and SHA-384 depending on the negotiated suite).
pub type BoxDigest = Box<dyn Digest + Send>;

impl Digest for Box<dyn Digest + Send> {
    fn update(&mut self, data: &[u8]) {
        (**self).update(data)
    }
    fn finalize(&mut self) -> Vec<u8> {
        (**self).finalize()
    }
    fn output_len(&self) -> usize {
        (**self).output_len()
    }
    fn block_len(&self) -> usize {
        (**self).block_len()
    }
    fn fork(&self) -> BoxDigest {
        (**self).fork()
    }
}

/// One-shot convenience: hash `data` and return the digest.
pub fn hash(d: &mut dyn Digest, data: &[u8]) -> Vec<u8> {
    d.update(data);
    d.finalize()
}

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,
];

const K384: [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,
];

const H256: [u32; 8] = [
    0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
];

const H384: [u64; 8] = [
    0xcbbb9d5dc1059ed8,
    0x629a292a367cd507,
    0x9159015a3070dd17,
    0x152fecd8f70e5939,
    0x67332667ffc00b31,
    0x8eb44a8768581511,
    0xdb0c2e0d64f98fa7,
    0x47b5481dbefa4fa4,
];

fn rotr(x: u32, n: u32) -> u32 {
    x.rotate_right(n)
}

/// SHA-256.
#[derive(Clone)]
pub struct Sha256 {
    state: [u32; 8],
    buf: [u8; 64],
    buf_len: usize,
    total: u64,
}

impl Default for Sha256 {
    fn default() -> Self {
        Self::new()
    }
}

impl Sha256 {
    /// New incremental SHA-256 hasher.
    pub fn new() -> Self {
        Self {
            state: H256,
            buf: [0u8; 64],
            buf_len: 0,
            total: 0,
        }
    }

    /// One-shot digest.
    pub fn oneshot(data: &[u8]) -> [u8; 32] {
        let mut h = Self::new();
        h.update(data);
        let out = h.finalize();
        let mut d = [0u8; 32];
        d.copy_from_slice(&out);
        d
    }

    fn compress(&mut self, block: &[u8]) {
        let mut w = [0u32; 64];
        for (i, word) in w.iter_mut().enumerate().take(16) {
            *word = u32::from_be_bytes([
                block[i * 4],
                block[i * 4 + 1],
                block[i * 4 + 2],
                block[i * 4 + 3],
            ]);
        }
        for i in 16..64 {
            let s0 = rotr(w[i - 15], 7) ^ rotr(w[i - 15], 18) ^ (w[i - 15] >> 3);
            let s1 = rotr(w[i - 2], 17) ^ rotr(w[i - 2], 19) ^ (w[i - 2] >> 10);
            w[i] = w[i - 16]
                .wrapping_add(s0)
                .wrapping_add(w[i - 7])
                .wrapping_add(s1);
        }
        let (mut a, mut b, mut c, mut d, mut e, mut f, mut g, mut h) = (
            self.state[0],
            self.state[1],
            self.state[2],
            self.state[3],
            self.state[4],
            self.state[5],
            self.state[6],
            self.state[7],
        );
        for i in 0..64 {
            let s1 = rotr(e, 6) ^ rotr(e, 11) ^ rotr(e, 25);
            let ch = (e & f) ^ (!e & g);
            let t1 = h
                .wrapping_add(s1)
                .wrapping_add(ch)
                .wrapping_add(K256[i])
                .wrapping_add(w[i]);
            let s0 = rotr(a, 2) ^ rotr(a, 13) ^ rotr(a, 22);
            let maj = (a & b) ^ (a & c) ^ (b & c);
            let t2 = s0.wrapping_add(maj);
            h = g;
            g = f;
            f = e;
            e = d.wrapping_add(t1);
            d = c;
            c = b;
            b = a;
            a = t1.wrapping_add(t2);
        }
        self.state[0] = self.state[0].wrapping_add(a);
        self.state[1] = self.state[1].wrapping_add(b);
        self.state[2] = self.state[2].wrapping_add(c);
        self.state[3] = self.state[3].wrapping_add(d);
        self.state[4] = self.state[4].wrapping_add(e);
        self.state[5] = self.state[5].wrapping_add(f);
        self.state[6] = self.state[6].wrapping_add(g);
        self.state[7] = self.state[7].wrapping_add(h);
    }
}

impl Digest for Sha256 {
    fn update(&mut self, data: &[u8]) {
        self.total = self.total.wrapping_add(data.len() as u64);
        let mut data = data;
        if self.buf_len > 0 {
            let take = core::cmp::min(64 - self.buf_len, data.len());
            self.buf[self.buf_len..self.buf_len + take].copy_from_slice(&data[..take]);
            self.buf_len += take;
            data = &data[take..];
            if self.buf_len == 64 {
                let block = self.buf;
                self.compress(&block);
                self.buf_len = 0;
            }
        }
        while data.len() >= 64 {
            let block: [u8; 64] = data[..64].try_into().unwrap();
            self.compress(&block);
            data = &data[64..];
        }
        if !data.is_empty() {
            self.buf[..data.len()].copy_from_slice(data);
            self.buf_len = data.len();
        }
    }

    fn finalize(&mut self) -> Vec<u8> {
        let bit_len = self.total.wrapping_mul(8);
        if self.buf_len < 56 {
            // Single final block.
            let mut b = [0u8; 64];
            b[..self.buf_len].copy_from_slice(&self.buf[..self.buf_len]);
            b[self.buf_len] = 0x80;
            b[56..64].copy_from_slice(&bit_len.to_be_bytes());
            self.compress(&b);
        } else {
            // Two blocks: padding block, then the length block.
            let mut b = [0u8; 64];
            b[..self.buf_len].copy_from_slice(&self.buf[..self.buf_len]);
            b[self.buf_len] = 0x80;
            self.compress(&b);
            let mut b = [0u8; 64];
            b[56..64].copy_from_slice(&bit_len.to_be_bytes());
            self.compress(&b);
        }
        let mut out = Vec::with_capacity(32);
        for v in self.state.iter() {
            out.extend_from_slice(&v.to_be_bytes());
        }
        self.state = H256;
        self.buf = [0u8; 64];
        self.buf_len = 0;
        self.total = 0;
        out
    }

    fn output_len(&self) -> usize {
        32
    }

    fn block_len(&self) -> usize {
        64
    }

    fn fork(&self) -> BoxDigest {
        Box::new(self.clone())
    }
}

/// SHA-384.
#[derive(Clone)]
pub struct Sha384 {
    state: [u64; 8],
    buf: [u8; 128],
    buf_len: usize,
    total: u64,
}

impl Default for Sha384 {
    fn default() -> Self {
        Self::new()
    }
}

impl Sha384 {
    /// New incremental SHA-384 hasher.
    pub fn new() -> Self {
        Self {
            state: H384,
            buf: [0u8; 128],
            buf_len: 0,
            total: 0,
        }
    }

    /// One-shot digest.
    pub fn oneshot(data: &[u8]) -> [u8; 48] {
        let mut h = Self::new();
        h.update(data);
        let out = h.finalize();
        let mut d = [0u8; 48];
        d.copy_from_slice(&out);
        d
    }

    fn compress(&mut self, block: &[u8]) {
        let mut w = [0u64; 80];
        for (i, word) in w.iter_mut().enumerate().take(16) {
            *word = u64::from_be_bytes([
                block[i * 8],
                block[i * 8 + 1],
                block[i * 8 + 2],
                block[i * 8 + 3],
                block[i * 8 + 4],
                block[i * 8 + 5],
                block[i * 8 + 6],
                block[i * 8 + 7],
            ]);
        }
        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, mut b, mut c, mut d, mut e, mut f, mut g, mut h) = (
            self.state[0],
            self.state[1],
            self.state[2],
            self.state[3],
            self.state[4],
            self.state[5],
            self.state[6],
            self.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 t1 = h
                .wrapping_add(s1)
                .wrapping_add(ch)
                .wrapping_add(K384[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 t2 = s0.wrapping_add(maj);
            h = g;
            g = f;
            f = e;
            e = d.wrapping_add(t1);
            d = c;
            c = b;
            b = a;
            a = t1.wrapping_add(t2);
        }
        self.state[0] = self.state[0].wrapping_add(a);
        self.state[1] = self.state[1].wrapping_add(b);
        self.state[2] = self.state[2].wrapping_add(c);
        self.state[3] = self.state[3].wrapping_add(d);
        self.state[4] = self.state[4].wrapping_add(e);
        self.state[5] = self.state[5].wrapping_add(f);
        self.state[6] = self.state[6].wrapping_add(g);
        self.state[7] = self.state[7].wrapping_add(h);
    }
}

impl Digest for Sha384 {
    fn update(&mut self, data: &[u8]) {
        self.total = self.total.wrapping_add(data.len() as u64);
        let mut data = data;
        if self.buf_len > 0 {
            let take = core::cmp::min(128 - self.buf_len, data.len());
            self.buf[self.buf_len..self.buf_len + take].copy_from_slice(&data[..take]);
            self.buf_len += take;
            data = &data[take..];
            if self.buf_len == 128 {
                let block = self.buf;
                self.compress(&block);
                self.buf_len = 0;
            }
        }
        while data.len() >= 128 {
            let block: [u8; 128] = data[..128].try_into().unwrap();
            self.compress(&block);
            data = &data[128..];
        }
        if !data.is_empty() {
            self.buf[..data.len()].copy_from_slice(data);
            self.buf_len = data.len();
        }
    }

    fn finalize(&mut self) -> Vec<u8> {
        let bit_len = self.total.wrapping_mul(8);
        // SHA-384 uses a 128-bit length field: high 64 bits always 0 here.
        let bit_len_hi = 0u64;
        let block_count = if self.buf_len < 112 { 1 } else { 2 };
        for i in 0..block_count {
            let mut b = [0u8; 128];
            b[..self.buf_len].copy_from_slice(&self.buf[..self.buf_len]);
            if i == 0 {
                b[self.buf_len] = 0x80;
            }
            if i == block_count - 1 {
                b[112..120].copy_from_slice(&bit_len_hi.to_be_bytes());
                b[120..128].copy_from_slice(&bit_len.to_be_bytes());
            }
            self.compress(&b);
        }
        let mut out = Vec::with_capacity(48);
        for v in self.state.iter() {
            out.extend_from_slice(&v.to_be_bytes());
        }
        // SHA-384 truncates to 48 bytes.
        out.truncate(48);
        self.state = H384;
        self.buf = [0u8; 128];
        self.buf_len = 0;
        self.total = 0;
        out
    }

    fn output_len(&self) -> usize {
        48
    }

    fn block_len(&self) -> usize {
        128
    }

    fn fork(&self) -> BoxDigest {
        Box::new(self.clone())
    }
}

impl fmt::Debug for Sha256 {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str("Sha256")
    }
}

impl fmt::Debug for Sha384 {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str("Sha384")
    }
}

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

    fn hex(d: &[u8]) -> String {
        let mut s = String::new();
        for b in d {
            s.push_str(&format!("{:02x}", b));
        }
        s
    }

    #[test]
    fn sha256_rfc_vectors() {
        // RFC 6234 / NIST vectors.
        assert_eq!(
            hex(&Sha256::oneshot(b"abc")),
            "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
        );
        assert_eq!(
            hex(&Sha256::oneshot(b"")),
            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
        );
        assert_eq!(
            hex(&Sha256::oneshot(
                b"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
            )),
            "248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1"
        );
        // One million 'a' (streamed to exercise the incremental path).
        let mut h = Sha256::new();
        let chunk = [b'a'; 1000];
        for _ in 0..1000 {
            h.update(&chunk);
        }
        assert_eq!(
            hex(&h.finalize()),
            "cdc76e5c9914fb9281a1c7e284d73e67f1809a48a497200e046d39ccc7112cd0"
        );
    }

    #[test]
    fn sha384_vectors() {
        assert_eq!(
            hex(&Sha384::oneshot(b"abc")),
            "cb00753f45a35e8bb5a03d699ac65007272c32ab0eded1631a8b605a43ff5bed\
             8086072ba1e7cc2358baeca134c825a7"
        );
        assert_eq!(
            hex(&Sha384::oneshot(b"")),
            "38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da\
             274edebfe76f65fbd51ad2f14898b95b"
        );
        let mut h = Sha384::new();
        let chunk = [b'a'; 1000];
        for _ in 0..1000 {
            h.update(&chunk);
        }
        assert_eq!(
            hex(&h.finalize()),
            "9d0e1809716474cb086e834e310a4a1ced149e9c00f248527972cec5704c2a5b\
             07b8b3dc38ecc4ebae97ddd87f3d8985"
        );
    }
}