block_modes/
ofb.rs

1use crate::{
2    traits::{BlockMode, IvState},
3    utils::{xor, Block},
4};
5use block_padding::Padding;
6use cipher::{generic_array::GenericArray, BlockCipher, BlockEncrypt};
7use core::marker::PhantomData;
8
9/// [Output feedback][1] (OFB) block mode instance with a full block feedback.
10///
11/// [1]: https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_feedback_(CFB)
12#[derive(Clone)]
13pub struct Ofb<C: BlockCipher + BlockEncrypt, P: Padding> {
14    cipher: C,
15    iv: GenericArray<u8, C::BlockSize>,
16    _p: PhantomData<P>,
17}
18
19impl<C, P> BlockMode<C, P> for Ofb<C, P>
20where
21    C: BlockCipher + BlockEncrypt,
22    P: Padding,
23{
24    type IvSize = C::BlockSize;
25
26    fn new(cipher: C, iv: &Block<C>) -> Self {
27        Self {
28            cipher,
29            iv: iv.clone(),
30            _p: Default::default(),
31        }
32    }
33
34    fn encrypt_blocks(&mut self, blocks: &mut [Block<C>]) {
35        for block in blocks.iter_mut() {
36            self.cipher.encrypt_block(&mut self.iv);
37            xor(block, &self.iv);
38        }
39    }
40
41    fn decrypt_blocks(&mut self, blocks: &mut [Block<C>]) {
42        self.encrypt_blocks(blocks)
43    }
44}
45
46impl<C, P> IvState<C, P> for Ofb<C, P>
47where
48    C: BlockCipher + BlockEncrypt,
49    P: Padding,
50{
51    fn iv_state(&self) -> GenericArray<u8, <Self as BlockMode<C, P>>::IvSize> {
52        self.iv.clone()
53    }
54}
block_modes/ofb.rs

block_modes/
ofb.rs
