noxid-cli 0.2.0

The Noxid compiler command line: check, build, test, adapt, and the agent surface
//! SHA-256, hand-rolled to keep the CLI free of external Rust dependencies.
//!
//! The vendored-plugin ledger (`.noxid-plugins.json`) records one content hash
//! per file so a scaffolded project can prove its copy of a vetted plugin is
//! the copy the compiler shipped. Nothing here is a security boundary on its
//! own: the ledger and the files it names live side by side, so the hash
//! detects drift and accident, not a determined rewriter.

const ROUND_CONSTANTS: [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,
];

/// Lowercase hexadecimal SHA-256 digest of `bytes`.
pub fn hex_digest(bytes: &[u8]) -> String {
    let mut state: [u32; 8] = [
        0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab,
        0x5be0cd19,
    ];
    let mut message = bytes.to_vec();
    let bit_length = (bytes.len() as u64).wrapping_mul(8);
    message.push(0x80);
    while message.len() % 64 != 56 {
        message.push(0);
    }
    message.extend_from_slice(&bit_length.to_be_bytes());

    for chunk in message.chunks_exact(64) {
        let mut schedule = [0u32; 64];
        for (index, word) in chunk.chunks_exact(4).enumerate() {
            schedule[index] = u32::from_be_bytes([word[0], word[1], word[2], word[3]]);
        }
        for index in 16..64 {
            let previous = schedule[index - 15];
            let ahead = schedule[index - 2];
            let s0 = previous.rotate_right(7) ^ previous.rotate_right(18) ^ (previous >> 3);
            let s1 = ahead.rotate_right(17) ^ ahead.rotate_right(19) ^ (ahead >> 10);
            schedule[index] = schedule[index - 16]
                .wrapping_add(s0)
                .wrapping_add(schedule[index - 7])
                .wrapping_add(s1);
        }
        let [mut a, mut b, mut c, mut d, mut e, mut f, mut g, mut h] = state;
        for index in 0..64 {
            let s1 = e.rotate_right(6) ^ e.rotate_right(11) ^ e.rotate_right(25);
            let choose = (e & f) ^ ((!e) & g);
            let temp1 = h
                .wrapping_add(s1)
                .wrapping_add(choose)
                .wrapping_add(ROUND_CONSTANTS[index])
                .wrapping_add(schedule[index]);
            let s0 = a.rotate_right(2) ^ a.rotate_right(13) ^ a.rotate_right(22);
            let majority = (a & b) ^ (a & c) ^ (b & c);
            let temp2 = s0.wrapping_add(majority);
            h = g;
            g = f;
            f = e;
            e = d.wrapping_add(temp1);
            d = c;
            c = b;
            b = a;
            a = temp1.wrapping_add(temp2);
        }
        for (slot, value) in state.iter_mut().zip([a, b, c, d, e, f, g, h]) {
            *slot = slot.wrapping_add(value);
        }
    }

    let mut hex = String::with_capacity(64);
    for word in state {
        hex.push_str(&format!("{word:08x}"));
    }
    hex
}

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

    #[test]
    fn known_vectors_match_the_published_digests() {
        assert_eq!(
            hex_digest(b""),
            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
        );
        assert_eq!(
            hex_digest(b"abc"),
            "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
        );
        assert_eq!(
            hex_digest(b"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"),
            "248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1"
        );
        // Longer than one padded block, so the message schedule carries state.
        assert_eq!(
            hex_digest(&b"a".repeat(1000)),
            "41edece42d63e8d9bf515a9ba6932e1c20cbc9f5a5d134645adb5db1b9737ea3"
        );
    }
}