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ofb.rs
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ofb.rs
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use crate::{
traits::BlockMode,
utils::{xor, Block},
};
use block_padding::Padding;
use cipher::{generic_array::GenericArray, BlockCipher, BlockEncrypt, NewBlockCipher};
use core::marker::PhantomData;
/// [Output feedback][1] (OFB) block mode instance with a full block feedback.
///
/// [1]: https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_feedback_(CFB)
#[derive(Clone)]
pub struct Ofb<C: BlockCipher + BlockEncrypt + NewBlockCipher, P: Padding> {
cipher: C,
iv: GenericArray<u8, C::BlockSize>,
_p: PhantomData<P>,
}
impl<C, P> BlockMode<C, P> for Ofb<C, P>
where
C: BlockCipher + BlockEncrypt + NewBlockCipher,
P: Padding,
{
type IvSize = C::BlockSize;
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>]) {
for block in blocks.iter_mut() {
self.cipher.encrypt_block(&mut self.iv);
xor(block, &self.iv);
}
}
fn decrypt_blocks(&mut self, blocks: &mut [Block<C>]) {
self.encrypt_blocks(blocks)
}
}