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use crate::Digest;
pub(super) const MD5_BLOCK_SIZE: usize = 64;
pub(super) const MD5_DIGEST_BITS_LEN: usize = 16 << 3;
pub(super) const MD5_INIT: [u32; 4] = [0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476];
#[derive(Clone)]
pub struct MD5 {
pub(super) digest: [u32; 4],
pub(super) buf: [u8; MD5_BLOCK_SIZE],
pub(super) idx: usize,
pub(super) len: usize,
is_checked: bool,
}
impl MD5 {
pub fn new() -> Self {
MD5 {
digest: MD5_INIT,
buf: [0; MD5_BLOCK_SIZE],
idx: 0,
len: 0,
is_checked: false,
}
}
}
impl Digest for MD5 {
fn block_size(&self) -> Option<usize> {
Some(64)
}
fn bits_len(&self) -> usize {
MD5_DIGEST_BITS_LEN
}
fn write(&mut self, data: &[u8]) {
let mut data = data;
self.len += data.len();
if self.idx > 0 {
let min = std::cmp::min(MD5_BLOCK_SIZE - self.idx, data.len());
let dst = &mut self.buf[self.idx..(self.idx+min)];
let src = &data[0..min];
dst.copy_from_slice(src);
self.idx += min;
if self.idx == MD5_BLOCK_SIZE {
self.update(None);
self.idx = 0;
}
data = &data[min..];
}
if data.len() >= MD5_BLOCK_SIZE {
let n = data.len() & (!(MD5_BLOCK_SIZE - 1));
let data_block = &data[0..n];
self.update(Some(data_block));
data = &data[n..];
}
if data.len() > 0 {
let dst = &mut self.buf[..data.len()];
dst.copy_from_slice(data);
self.idx += data.len();
}
self.is_checked = false;
}
fn checksum(&mut self, digest: &mut Vec<u8>) {
if !self.is_checked {
let mut tmp = [0u8; 1+63+8];
tmp[0] = 0x80;
let pad_len = 55usize.wrapping_sub(self.len) % 64;
let len = (self.len << 3) as u64;
let src = len.to_le_bytes();
let dst = &mut tmp[(1+pad_len)..(1+pad_len+8)];
dst.copy_from_slice(&src[..]);
self.write(&tmp[0..(1+pad_len+8)]);
self.len = 0;
self.is_checked = true;
}
digest.clear();
self.digest.iter().for_each(|&e| {
digest.extend(e.to_le_bytes().iter());
});
}
fn reset(&mut self) {
*self = MD5::new();
}
}
#[cfg(test)]
mod tests {
use crate::{Digest, MD5};
fn cvt_bytes_to_str(b: &[u8]) -> String {
let mut s= String::new();
for &ele in b.iter() {
let e = format!("{:02x}", ele);
s.push_str(e.as_str());
}
s
}
#[test]
fn md5() {
let cases = [
("d41d8cd98f00b204e9800998ecf8427e", ""),
("0cc175b9c0f1b6a831c399e269772661", "a"),
("187ef4436122d1cc2f40dc2b92f0eba0", "ab"),
("900150983cd24fb0d6963f7d28e17f72", "abc"),
("e2fc714c4727ee9395f324cd2e7f331f", "abcd"),
("ab56b4d92b40713acc5af89985d4b786", "abcde"),
("e80b5017098950fc58aad83c8c14978e", "abcdef"),
("7ac66c0f148de9519b8bd264312c4d64", "abcdefg"),
("e8dc4081b13434b45189a720b77b6818", "abcdefgh"),
("8aa99b1f439ff71293e95357bac6fd94", "abcdefghi"),
("a925576942e94b2ef57a066101b48876", "abcdefghij"),
("d747fc1719c7eacb84058196cfe56d57", "Discard medicine more than two years old."),
("bff2dcb37ef3a44ba43ab144768ca837", "He who has a shady past knows that nice guys finish last."),
("0441015ecb54a7342d017ed1bcfdbea5", "I wouldn't marry him with a ten foot pole."),
("9e3cac8e9e9757a60c3ea391130d3689", "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"),
("a0f04459b031f916a59a35cc482dc039", "The days of the digital watch are numbered. -Tom Stoppard"),
("e7a48e0fe884faf31475d2a04b1362cc", "Nepal premier won't resign."),
("637d2fe925c07c113800509964fb0e06", "For every action there is an equal and opposite government program."),
("834a8d18d5c6562119cf4c7f5086cb71", "His money is twice tainted: 'taint yours and 'taint mine."),
("de3a4d2fd6c73ec2db2abad23b444281", "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"),
("acf203f997e2cf74ea3aff86985aefaf", "It's a tiny change to the code and not completely disgusting. - Bob Manchek"),
("e1c1384cb4d2221dfdd7c795a4222c9a", "size: a.out: bad magic"),
("c90f3ddecc54f34228c063d7525bf644", "The major problem is with sendmail. -Mark Horton"),
("cdf7ab6c1fd49bd9933c43f3ea5af185", "Give me a rock, paper and scissors and I will move the world. CCFestoon"),
("83bc85234942fc883c063cbd7f0ad5d0", "If the enemy is within range, then so are you."),
("277cbe255686b48dd7e8f389394d9299", "It's well we cannot hear the screams/That we create in others' dreams."),
("fd3fb0a7ffb8af16603f3d3af98f8e1f", "You remind me of a TV show, but that's all right: I watch it anyway."),
("469b13a78ebf297ecda64d4723655154", "C is as portable as Stonehedge!!"),
("63eb3a2f466410104731c4b037600110", "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"),
("72c2ed7592debca1c90fc0100f931a2f", "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction. Lewis-Randall Rule"),
("132f7619d33b523b1d9e5bd8e0928355", "How can you write a big system without C++? -Paul Glick"),
];
let mut md5 = MD5::new();
let mut digest = Vec::with_capacity(md5.bits_len() >> 3);
cases.iter().for_each(|e| {
md5.write((e.1).as_bytes());
md5.checksum(&mut digest);
println!("{},{:#x}", e.0, digest.iter().fold(0, |sum, &d| { (d as u128) | (sum << 8)}));
assert_eq!(e.0, cvt_bytes_to_str(digest.as_slice()), "cases: {}", e.1);
md5.reset();
})
}
}