use crate::{buffer::BlockBuffer, digest::Digest, encoding::DigestBytes};
const INITIAL_STATE: [u32; 4] = [0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476];
const SHIFT_AMOUNTS: [u32; 64] = [
7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9,
14, 20, 5, 9, 14, 20, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 6, 10, 15,
21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21,
];
const TABLE: [u32; 64] = [
0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be, 0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c, 0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05, 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, 0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391,
];
#[derive(Clone, Debug)]
pub struct Md5 {
state: [u32; 4],
buffer: BlockBuffer<64, 8, false>,
}
#[allow(non_camel_case_types)]
pub type MD5 = Md5;
impl Default for Md5 {
fn default() -> Self {
Self::new()
}
}
impl Md5 {
pub fn new() -> Self {
Self {
state: INITIAL_STATE,
buffer: BlockBuffer::new(),
}
}
pub fn digest(data: &[u8]) -> DigestBytes {
<Self as Digest>::digest(data)
}
pub fn finalize_hex(self) -> String {
<Self as Digest>::finalize_hex(self)
}
}
impl Digest for Md5 {
const OUTPUT_SIZE: usize = 16;
fn update(&mut self, data: &[u8]) {
let state = &mut self.state;
self.buffer.update(data, |block| compress_md5(state, block));
}
fn input_size(&self) -> u128 {
self.buffer.message_len()
}
fn reset(&mut self) {
self.state = INITIAL_STATE;
self.buffer.reset();
}
fn finalize(mut self) -> DigestBytes {
let state = &mut self.state;
self.buffer.finalize(|block| compress_md5(state, block));
let mut bytes = Vec::with_capacity(Self::OUTPUT_SIZE);
for word in &self.state {
bytes.extend_from_slice(&word.to_le_bytes());
}
DigestBytes::new(bytes)
}
}
fn compress_md5(state: &mut [u32; 4], block: &[u8; 64]) {
let words = decode_le_u32_words(block);
let [mut a, mut b, mut c, mut d] = *state;
for round in 0..64 {
let (f, g) = match round {
0..=15 => ((b & c) | (!b & d), round),
16..=31 => ((d & b) | (!d & c), (5 * round + 1) % 16),
32..=47 => (b ^ c ^ d, (3 * round + 5) % 16),
_ => (c ^ (b | !d), (7 * round) % 16),
};
let next = a
.wrapping_add(f)
.wrapping_add(TABLE[round])
.wrapping_add(words[g]);
let rotated = next.rotate_left(SHIFT_AMOUNTS[round]);
a = d;
d = c;
c = b;
b = b.wrapping_add(rotated);
}
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);
}
fn decode_le_u32_words(block: &[u8; 64]) -> [u32; 16] {
#[cfg(feature = "simd")]
{
if let Some(words) = super::simd::decode_le_u32x16(block) {
return words;
}
}
let mut words = [0u32; 16];
for (word, chunk) in words.iter_mut().zip(block.chunks_exact(4)) {
*word = u32::from_le_bytes(chunk.try_into().expect("chunk has 4 bytes"));
}
words
}
#[cfg(all(test, feature = "simd"))]
pub(crate) fn decode_le_u32_words_scalar(block: &[u8; 64]) -> [u32; 16] {
let mut words = [0u32; 16];
for (word, chunk) in words.iter_mut().zip(block.chunks_exact(4)) {
*word = u32::from_le_bytes(chunk.try_into().expect("chunk has 4 bytes"));
}
words
}
#[cfg(all(test, feature = "simd"))]
mod tests {
use super::{decode_le_u32_words, decode_le_u32_words_scalar};
#[test]
fn md5_word_decode_matches_scalar() {
let mut block = [0u8; 64];
for (index, byte) in block.iter_mut().enumerate() {
*byte = 255 - index as u8;
}
assert_eq!(
decode_le_u32_words_scalar(&block),
decode_le_u32_words(&block)
);
}
}