1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
use block_cipher_trait::generic_array::GenericArray;
use block_cipher_trait::generic_array::typenum::Unsigned;
use block_cipher_trait::BlockCipher;
use block_padding::Padding;
use traits::BlockMode;
use utils::{xor, get_par_blocks, ParBlocks, Block};
use core::marker::PhantomData;
pub struct Cbc<C: BlockCipher, P: Padding> {
cipher: C,
iv: GenericArray<u8, C::BlockSize>,
_p: PhantomData<P>,
}
impl<C: BlockCipher, P: Padding> Cbc<C, P> {
#[inline(always)]
fn single_blocks_decrypt(&mut self, blocks: &mut [Block<C>]) {
let mut iv = self.iv.clone();
for block in blocks {
let block_copy = block.clone();
self.cipher.decrypt_block(block);
xor(block, iv.as_slice());
iv = block_copy;
}
self.iv = iv;
}
}
impl<C: BlockCipher, P: Padding> BlockMode<C, P> for Cbc<C, P> {
fn new(cipher: C, iv: &Block<C>) -> Self {
Self {
cipher,
iv: iv.clone(),
_p: Default::default(),
}
}
fn encrypt_blocks(&mut self, blocks: &mut [Block<C>]) {
self.iv = {
let mut iv = &self.iv;
for block in blocks {
xor(block, &iv);
self.cipher.encrypt_block(block);
iv = block;
}
iv.clone()
};
}
fn decrypt_blocks(&mut self, blocks: &mut [Block<C>]) {
let pbn = C::ParBlocks::to_usize();
if pbn != 1 {
let (par_blocks, leftover) = get_par_blocks::<C>(blocks);
let mut iv_buf = ParBlocks::<C>::default();
iv_buf[0] = self.iv.clone();
for pb in par_blocks {
iv_buf[1..].clone_from_slice(&pb[..pbn-1]);
let next_iv = pb[pbn - 1].clone();
self.cipher.decrypt_blocks(pb);
pb.iter_mut().zip(iv_buf.iter()).for_each(|(a, b)| xor(a, b));
iv_buf[0] = next_iv;
}
self.iv = iv_buf[0].clone();
self.single_blocks_decrypt(leftover);
} else {
self.single_blocks_decrypt(blocks);
}
}
}