quantydb-sqlite 0.4.0

//! Shared test helpers: a SHA-256 and the canonical rendering of a row.
//!
//! The hash is written out here rather than pulled in, because a test only
//! dependency is still a dependency (ADR-008, ADR-013) and this one is
//! eighty lines. It is checked against the published test vectors in
//! `sha256_matches_the_published_vectors`, so the oracle it verifies rests
//! on something independently verifiable rather than on our own say so.

#![allow(dead_code)]

const K: [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,
];

/// A streaming SHA-256, so a table can be hashed row by row without ever
/// holding the whole rendering in memory.
pub struct Sha256 {
    state: [u32; 8],
    buffer: [u8; 64],
    buffered: usize,
    length: u64,
}

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

impl Sha256 {
    pub fn new() -> Sha256 {
        Sha256 {
            state: [
                0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab,
                0x5be0cd19,
            ],
            buffer: [0u8; 64],
            buffered: 0,
            length: 0,
        }
    }

    pub fn update(&mut self, mut data: &[u8]) {
        self.length = self.length.wrapping_add(data.len() as u64);
        if self.buffered > 0 {
            let take = (64 - self.buffered).min(data.len());
            self.buffer[self.buffered..self.buffered + take].copy_from_slice(&data[..take]);
            self.buffered += take;
            data = &data[take..];
            if self.buffered == 64 {
                let block = self.buffer;
                self.compress(&block);
                self.buffered = 0;
            }
        }
        while data.len() >= 64 {
            let (block, rest) = data.split_at(64);
            let mut fixed = [0u8; 64];
            fixed.copy_from_slice(block);
            self.compress(&fixed);
            data = rest;
        }
        if !data.is_empty() {
            self.buffer[..data.len()].copy_from_slice(data);
            self.buffered = data.len();
        }
    }

    pub fn finish(mut self) -> String {
        let bits = self.length.wrapping_mul(8);
        self.update(&[0x80]);
        while self.buffered != 56 {
            self.update(&[0x00]);
        }
        // update() counted the padding, so the length written here is the
        // one captured before it
        let mut block = self.buffer;
        block[56..].copy_from_slice(&bits.to_be_bytes());
        self.compress(&block);

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

    fn compress(&mut self, block: &[u8; 64]) {
        let mut w = [0u32; 64];
        for (i, chunk) in block.as_chunks::<4>().0.iter().enumerate() {
            w[i] = u32::from_be_bytes([chunk[0], chunk[1], chunk[2], chunk[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, mut b, mut c, mut d, mut e, mut f, mut g, mut h] = self.state;
        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(K[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);
        }
        for (slot, value) in self.state.iter_mut().zip([a, b, c, d, e, f, g, h]) {
            *slot = slot.wrapping_add(value);
        }
    }
}

pub fn sha256_hex(data: &[u8]) -> String {
    let mut hasher = Sha256::new();
    hasher.update(data);
    hasher.finish()
}

pub fn hex(bytes: &[u8]) -> String {
    let mut out = String::with_capacity(bytes.len() * 2);
    for b in bytes {
        out.push_str(&format!("{b:02x}"));
    }
    out
}