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Simpify aes_ctr API to just crypt

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Marc Brinkmann 2020-10-03 16:28:59 +02:00 • committed by Lireer
parent 9f6ee0f4b6
commit a5d1905db6
1 changed files with 17 additions and 58 deletions
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75
src/aes_ctr.rs
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@ -82,46 +82,25 @@ where
C::Cipher: BlockCipher,
{
/// Decrypt or encrypt given data.
pub fn crypt(&mut self, mut data: &mut [u8]) {
while data.len() > 0 {
let mut buffer: [u8; AES_BLOCK_SIZE] = [0u8; AES_BLOCK_SIZE];
let target_len = data.len().min(AES_BLOCK_SIZE);
// Fill buffer with enough data to decrypt the next block.
debug_assert_eq!(
self.read(&mut buffer[0..target_len])
.expect("reading key stream should never fail"),
target_len
);
xor(&mut data[0..target_len], &buffer.as_slice()[0..target_len]);
data = &mut data[target_len..];
}
}
}
impl<C> io::Read for AesCtrZipKeyStream<C>
where
C: AesKind,
C::Cipher: BlockCipher,
{
#[inline]
fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
if self.buffer.len() == 0 {
// Note: AES block size is always 16 bytes, same as u128.
let mut block = GenericArray::clone_from_slice(&self.counter.to_le_bytes());
self.cipher.encrypt_block(&mut block);
self.counter += 1;
self.buffer = block.into_iter().collect();
fn crypt(&mut self, mut target: &mut [u8]) {
while target.len() > 0 {
if self.buffer.len() == 0 {
// Note: AES block size is always 16 bytes, same as u128.
let mut block = GenericArray::clone_from_slice(&self.counter.to_le_bytes());
// TODO: Use trait.
self.cipher.encrypt_block(&mut block);
self.counter += 1;
self.buffer = block.into_iter().collect();
}
let target_len = target.len().min(self.buffer.len());
xor(&mut target[0..target_len], &self.buffer[0..target_len]);
self.buffer.drain(0..target_len);
target = &mut target[target_len..];
}
let target_len = buf.len().min(self.buffer.len());
buf.copy_from_slice(&self.buffer[0..target_len]);
self.buffer.drain(0..target_len);
Ok(target_len)
}
}
@ -140,26 +119,6 @@ mod tests {
use super::{xor, Aes256, AesCtrZipKeyStream};
use std::io::Read;
#[test]
fn simple_example() {
let ciphertext: [u8; 5] = [0xdc, 0x99, 0x93, 0x5e, 0xbf];
let expected_plaintext = &[b'a', b's', b'd', b'f', b'\n'];
let key = [
0xd1, 0x51, 0xa6, 0xab, 0x53, 0x68, 0xd7, 0xb7, 0xbf, 0x49, 0xf7, 0xf5, 0x8a, 0x4e,
0x10, 0x36, 0x25, 0x1c, 0x13, 0xba, 0x12, 0x45, 0x37, 0x65, 0xa9, 0xe4, 0xed, 0x9f,
0x4a, 0xa8, 0xda, 0x3b,
];
let mut key_stream = AesCtrZipKeyStream::<Aes256>::new(&key);
let mut key_buf = [0u8; 5];
key_stream.read(&mut key_buf).unwrap();
let mut plaintext = ciphertext;
xor(&mut plaintext, &key_buf);
assert_eq!(&plaintext, expected_plaintext);
}
#[test]
fn crypt_simple_example() {
let ciphertext: [u8; 5] = [0xdc, 0x99, 0x93, 0x5e, 0xbf];