/
cryptoutil.rs
271 lines (221 loc) · 8.84 KB
/
cryptoutil.rs
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// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::num::{Zero, CheckedAdd};
use std::vec::bytes::{MutableByteVector, copy_memory};
/// Write a u32 into a vector, which must be 4 bytes long. The value is written in big-endian
/// format.
pub fn write_u32_be(dst: &mut[u8], input: u32) {
use std::cast::transmute;
use std::unstable::intrinsics::to_be32;
assert!(dst.len() == 4);
unsafe {
let x: *mut i32 = transmute(dst.unsafe_mut_ref(0));
*x = to_be32(input as i32);
}
}
/// Read a vector of bytes into a vector of u32s. The values are read in big-endian format.
pub fn read_u32v_be(dst: &mut[u32], input: &[u8]) {
use std::cast::transmute;
use std::unstable::intrinsics::to_be32;
assert!(dst.len() * 4 == input.len());
unsafe {
let mut x: *mut i32 = transmute(dst.unsafe_mut_ref(0));
let mut y: *i32 = transmute(input.unsafe_ref(0));
do dst.len().times() {
*x = to_be32(*y);
x = x.offset(1);
y = y.offset(1);
}
}
}
trait ToBits {
/// Convert the value in bytes to the number of bits, a tuple where the 1st item is the
/// high-order value and the 2nd item is the low order value.
fn to_bits(self) -> (Self, Self);
}
impl ToBits for u64 {
fn to_bits(self) -> (u64, u64) {
return (self >> 61, self << 3);
}
}
/// Adds the specified number of bytes to the bit count. fail!() if this would cause numeric
/// overflow.
pub fn add_bytes_to_bits<T: Int + CheckedAdd + ToBits>(bits: T, bytes: T) -> T {
let (new_high_bits, new_low_bits) = bytes.to_bits();
if new_high_bits > Zero::zero() {
fail!("Numeric overflow occured.")
}
match bits.checked_add(&new_low_bits) {
Some(x) => return x,
None => fail!("Numeric overflow occured.")
}
}
/// A FixedBuffer, likes its name implies, is a fixed size buffer. When the buffer becomes full, it
/// must be processed. The input() method takes care of processing and then clearing the buffer
/// automatically. However, other methods do not and require the caller to process the buffer. Any
/// method that modifies the buffer directory or provides the caller with bytes that can be modifies
/// results in those bytes being marked as used by the buffer.
pub trait FixedBuffer {
/// Input a vector of bytes. If the buffer becomes full, process it with the provided
/// function and then clear the buffer.
fn input(&mut self, input: &[u8], func: &fn(&[u8]));
/// Reset the buffer.
fn reset(&mut self);
/// Zero the buffer up until the specified index. The buffer position currently must not be
/// greater than that index.
fn zero_until(&mut self, idx: uint);
/// Get a slice of the buffer of the specified size. There must be at least that many bytes
/// remaining in the buffer.
fn next<'s>(&'s mut self, len: uint) -> &'s mut [u8];
/// Get the current buffer. The buffer must already be full. This clears the buffer as well.
fn full_buffer<'s>(&'s mut self) -> &'s [u8];
/// Get the current position of the buffer.
fn position(&self) -> uint;
/// Get the number of bytes remaining in the buffer until it is full.
fn remaining(&self) -> uint;
/// Get the size of the buffer
fn size(&self) -> uint;
}
/// A fixed size buffer of 64 bytes useful for cryptographic operations.
pub struct FixedBuffer64 {
priv buffer: [u8, ..64],
priv buffer_idx: uint,
}
impl FixedBuffer64 {
/// Create a new buffer
pub fn new() -> FixedBuffer64 {
return FixedBuffer64 {
buffer: [0u8, ..64],
buffer_idx: 0
};
}
}
impl FixedBuffer for FixedBuffer64 {
fn input(&mut self, input: &[u8], func: &fn(&[u8])) {
let mut i = 0;
// FIXME: #6304 - This local variable shouldn't be necessary.
let size = 64;
// If there is already data in the buffer, copy as much as we can into it and process
// the data if the buffer becomes full.
if self.buffer_idx != 0 {
let buffer_remaining = size - self.buffer_idx;
if input.len() >= buffer_remaining {
copy_memory(
self.buffer.mut_slice(self.buffer_idx, size),
input.slice_to(buffer_remaining),
buffer_remaining);
self.buffer_idx = 0;
func(self.buffer);
i += buffer_remaining;
} else {
copy_memory(
self.buffer.mut_slice(self.buffer_idx, self.buffer_idx + input.len()),
input,
input.len());
self.buffer_idx += input.len();
return;
}
}
// While we have at least a full buffer size chunks's worth of data, process that data
// without copying it into the buffer
while input.len() - i >= size {
func(input.slice(i, i + size));
i += size;
}
// Copy any input data into the buffer. At this point in the method, the ammount of
// data left in the input vector will be less than the buffer size and the buffer will
// be empty.
let input_remaining = input.len() - i;
copy_memory(
self.buffer.mut_slice(0, input_remaining),
input.slice_from(i),
input.len() - i);
self.buffer_idx += input_remaining;
}
fn reset(&mut self) {
self.buffer_idx = 0;
}
fn zero_until(&mut self, idx: uint) {
assert!(idx >= self.buffer_idx);
self.buffer.mut_slice(self.buffer_idx, idx).set_memory(0);
self.buffer_idx = idx;
}
fn next<'s>(&'s mut self, len: uint) -> &'s mut [u8] {
self.buffer_idx += len;
return self.buffer.mut_slice(self.buffer_idx - len, self.buffer_idx);
}
fn full_buffer<'s>(&'s mut self) -> &'s [u8] {
assert!(self.buffer_idx == 64);
self.buffer_idx = 0;
return self.buffer.slice_to(64);
}
fn position(&self) -> uint { self.buffer_idx }
fn remaining(&self) -> uint { 64 - self.buffer_idx }
fn size(&self) -> uint { 64 }
}
/// The StandardPadding trait adds a method useful for various hash algorithms to a FixedBuffer
/// struct.
pub trait StandardPadding {
/// Add standard padding to the buffer. The buffer must not be full when this method is called
/// and is guaranteed to have exactly rem remaining bytes when it returns. If there are not at
/// least rem bytes available, the buffer will be zero padded, processed, cleared, and then
/// filled with zeros again until only rem bytes are remaining.
fn standard_padding(&mut self, rem: uint, func: &fn(&[u8]));
}
impl <T: FixedBuffer> StandardPadding for T {
fn standard_padding(&mut self, rem: uint, func: &fn(&[u8])) {
let size = self.size();
self.next(1)[0] = 128;
if self.remaining() < rem {
self.zero_until(size);
func(self.full_buffer());
}
self.zero_until(size - rem);
}
}
#[cfg(test)]
pub mod test {
use std::rand::{IsaacRng, Rng};
use std::vec;
use extra::hex::FromHex;
use cryptoutil::add_bytes_to_bits;
use digest::Digest;
/// Feed 1,000,000 'a's into the digest with varying input sizes and check that the result is
/// correct.
pub fn test_digest_1million_random<D: Digest>(digest: &mut D, blocksize: uint, expected: &str) {
let total_size = 1000000;
let buffer = vec::from_elem(blocksize * 2, 'a' as u8);
let mut rng = IsaacRng::new_unseeded();
let mut count = 0;
digest.reset();
while count < total_size {
let next: uint = rng.gen_range(0, 2 * blocksize + 1);
let remaining = total_size - count;
let size = if next > remaining { remaining } else { next };
digest.input(buffer.slice_to(size));
count += size;
}
let result_str = digest.result_str();
let result_bytes = digest.result_bytes();
assert_eq!(expected, result_str.as_slice());
assert_eq!(expected.from_hex().unwrap(), result_bytes);
}
// A normal addition - no overflow occurs
#[test]
fn test_add_bytes_to_bits_ok() {
assert!(add_bytes_to_bits::<u64>(100, 10) == 180);
}
// A simple failure case - adding 1 to the max value
#[test]
#[should_fail]
fn test_add_bytes_to_bits_overflow() {
add_bytes_to_bits::<u64>(Bounded::max_value(), 1);
}
}