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// Copyright © 2022-2023 Mini Functions. All rights reserved.
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT
//!
//! # A Rust library that implements the MD5 cryptographic hash function
//!
//! [](https://minifunctions.com)
//!
//! <center>
//!
//! [](https://www.rust-lang.org)
//! [](https://crates.io/crates/mini-functions)
//! [](https://lib.rs/crates/mini-functions)
//! [](https://github.com/sebastienrousseau/mini-functions)
//! [](http://opensource.org/licenses/MIT)
//!
//! </center>
//!
//! ## Overview
//!
//! The Message Digest (MDG) is an easy way to produces a 128-bit
//! (16-byte) hash value using the MD5 cryptographic hash function. It
//! provides a struct, MD5, that can generate a message digest of data
//! in a secure, one-way hash. The message digest can verify the
//! integrity of the data without having to store the entire message.
//!
//! Several options are available to produce the hash value:
//!
//! - `MD5::default()` - Returns the hash value of an empty string.
//! - `MD5::digest()` - Returns the hash value of a string.
//! - `MD5::finalize()` - Finalize the MD5 object and return the result
//! as a 16-byte array.
//! - `MD5::hexdigest()` - Returns the hash value of a string as a
//! hexadecimal string.
//! - `MD5::new()` - Create a new instance of the MD5 struct.
//! - `MD5::reset()` - Reset the internal state of the MD5 object.
//! - `MD5::to_hex_string()` - Returns the hash value of a string as a
//! hexadecimal string.
//! - `MD5::to_string()` - Returns the hash value of a string as a
//! string.
//! - `MD5::update()` - Update the internal state of the MD5 object
//! with new data.
//! - `MD5::update_file()` - Update the internal state of the MD5
//! object with new data from a file.
//!
//! To use this crate, add `mdg` to your `Cargo.toml`:
//!
//! ```toml
//! [dependencies]
//! mdg = "0.0.1"
//! ```
//!
//! ## Usage
//!
//! - [`serde`][]: Enable serialization/deserialization via serde
//!
//! # Examples
//!
//! ```no_run
//! use mdg::MD5;
//!
//! let hash = MD5::default();
//! assert_eq!(hash.to_string(), "d41d8cd98f00b204e9800998ecf8427e");
//! ```
//! # Warning
//!
//! This crate is not intended for cryptographic use. MD5 is not a
//! cryptographically secure hashing algorithm and should not be used
//! for applications that require a collision-resistant hash function.
//!
//! MD5 is sensitive to length extension attacks, which alter the hash
//! value if additional data is appended to the input.
//!
//! [`serde`]: https://github.com/serde-rs/serde
//!
#![cfg_attr(feature = "bench", feature(test))]
#![deny(dead_code)]
#![deny(missing_debug_implementations)]
#![deny(missing_docs)]
#![forbid(unsafe_code)]
#![warn(unreachable_pub)]
#![doc(
html_favicon_url = "https://raw.githubusercontent.com/sebastienrousseau/vault/main/assets/mini-functions/icons/ico-mdg.svg",
html_logo_url = "https://raw.githubusercontent.com/sebastienrousseau/vault/main/assets/mini-functions/icons/ico-mdg.svg",
html_root_url = "https://docs.rs/mdg"
)]
#![crate_name = "mdg"]
#![crate_type = "lib"]
/// Import the `params` module.
mod params;
pub use params::*;
/// Import the `constants` module.
pub mod constants;
pub use constants::*;
/// Import the `digest` module.
pub mod digest;
pub use digest::*;
use std::convert::TryInto;
use std::fmt::Display;
/// The MD5 struct.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct MD5 {
/// The buffer.
pub buffer: [u8; BLOCK_LENGTH],
/// The count.
pub count: [u32; 2],
/// The digest.
pub digest: [u8; DIGEST_LENGTH],
/// The state.
pub state: [u32; 4],
}
impl MD5 {
/// Finalize the MD5 object and return the result as a 16-byte array.
pub fn finalize(&mut self) -> &Self {
// Save the length before padding.
let bits: [u8; 8] = (0..8)
.into_iter()
.map(|i| (self.count[i >> 2] >> ((i & 3) << 3)) as u8)
.collect::<Vec<_>>()
.try_into()
.expect("Couldn't transform vec into array");
// Pad out to 56 mod 64
let index = (self.count[0] >> 3) & 63;
let pad_len = if index < 56 { 56 - index } else { 120 - index };
self.update_with_len(&PADDING, pad_len as usize);
// Append the length
self.update(&bits);
self.digest = (0..DIGEST_LENGTH)
.into_iter()
.map(|i| (self.state[i >> 2] >> ((i & 3) << 3)) as u8)
.collect::<Vec<_>>()
.try_into()
.expect("Couldn't transform vec into array");
self
}
/// Create a new instance of the MD5 struct.
pub fn new() -> Self {
Self {
state: INITIAL_STATE,
count: [0, 0],
buffer: [0; BLOCK_LENGTH],
digest: [0; DIGEST_LENGTH],
}
}
/// Update the internal state of the MD5 object with new data.
pub fn transform(&mut self, data: &[u8]) -> &mut Self {
const fn f(x: u32, y: u32, z: u32) -> u32 {
(x & y) | (!x & z)
}
const fn g(x: u32, y: u32, z: u32) -> u32 {
(x & z) | (y & !z)
}
const fn h(x: u32, y: u32, z: u32) -> u32 {
x ^ y ^ z
}
const fn i(x: u32, y: u32, z: u32) -> u32 {
y ^ (x | !z)
}
let (mut a, mut b, mut c, mut d): (u32, u32, u32, u32) =
(self.state[0], self.state[1], self.state[2], self.state[3]);
for (idx, t_value) in T_VALUES.iter().enumerate() {
let (value, g): (u32, usize) = match idx {
0..=15 => (f(b, c, d), idx),
16..=31 => (g(b, c, d), (5 * idx + 1) % DIGEST_LENGTH),
32..=47 => (h(b, c, d), (3 * idx + 5) % DIGEST_LENGTH),
48..=63 => (i(b, c, d), (7 * idx) % DIGEST_LENGTH),
_ => unreachable!(),
};
let part_value = u32::from_ne_bytes(
data[4 * g..4 * g + 4]
.try_into()
.expect("Couldn't transform slice into array"),
);
let f = value
.wrapping_add(a)
.wrapping_add(*t_value)
.wrapping_add(part_value);
a = d;
d = c;
c = b;
b = b.wrapping_add(f.rotate_left(SHIFTS[idx].into()));
}
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
}
/// Update the internal state of the MD5 object with new data.
pub fn update_with_len(&mut self, value: &[u8], nbytes: usize) -> &mut Self {
// Compute number of bytes mod 64
let mut offset = ((self.count[0] >> 3) & 63) as usize;
let nbits = (nbytes << 3) as u32;
let p = value;
if nbytes == 0 {
return self;
}
// Update the number of bits
self.count[0] = self.count[0].wrapping_add(nbits);
if self.count[0] < nbits {
self.count[1] += 1;
}
self.count[1] += (nbytes >> 29) as u32;
let part_len = BLOCK_LENGTH - offset;
let mut i = part_len;
// Transform as many times as possible
if nbytes >= part_len {
self.buffer[offset..(offset + part_len)].clone_from_slice(&p[..part_len]);
let buf = self.buffer;
self.transform(&buf);
while i < nbytes - part_len {
if nbytes - i >= 64 {
let buf = self.buffer[i..i + part_len].to_vec();
self.transform(&buf);
i += 64;
} else {
break;
}
}
offset = 0;
} else {
i = 0;
}
// Add remaining input in buffer
self.buffer[offset..(offset + nbytes - i)].clone_from_slice(&p[i..nbytes]);
self
}
}
impl Default for MD5 {
/// Create a new instance of the MD5 struct.
fn default() -> Self {
Self::new()
}
}
impl Display for MD5 {
/// Display the current MD5 value.
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
for di in self.digest {
write!(f, "{di:02x}")?;
}
Ok(())
}
}