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use crate::{
chacha::{ChaCha, Key},
max_blocks::C64,
rounds::R20,
};
use cipher::{
consts::{U32, U8},
errors::{LoopError, OverflowError},
NewCipher, SeekNum, StreamCipher, StreamCipherSeek,
};
#[cfg_attr(docsrs, doc(cfg(feature = "legacy")))]
pub type LegacyNonce = cipher::Nonce<ChaCha20Legacy>;
#[cfg_attr(docsrs, doc(cfg(feature = "legacy")))]
pub struct ChaCha20Legacy(ChaCha<R20, C64>);
impl NewCipher for ChaCha20Legacy {
type KeySize = U32;
type NonceSize = U8;
fn new(key: &Key, nonce: &LegacyNonce) -> Self {
let mut exp_iv = [0u8; 12];
exp_iv[4..].copy_from_slice(nonce);
ChaCha20Legacy(ChaCha::new(key, &exp_iv.into()))
}
}
impl StreamCipher for ChaCha20Legacy {
fn try_apply_keystream(&mut self, data: &mut [u8]) -> Result<(), LoopError> {
self.0.try_apply_keystream(data)
}
}
impl StreamCipherSeek for ChaCha20Legacy {
fn try_current_pos<T: SeekNum>(&self) -> Result<T, OverflowError> {
self.0.try_current_pos()
}
fn try_seek<T: SeekNum>(&mut self, pos: T) -> Result<(), LoopError> {
self.0.try_seek(pos)
}
}