// option. This file may not be copied, modified, or distributed
// except according to those terms.
+use std::io;
+
#[cfg(not(feature = "fuzztarget"))]
mod real_chacha {
use std::cmp;
}
}
+ const BLOCK_SIZE: usize = 64;
+
#[derive(Clone,Copy)]
struct ChaChaState {
a: u32x4,
#[derive(Copy)]
pub struct ChaCha20 {
state : ChaChaState,
- output : [u8; 64],
+ output : [u8; BLOCK_SIZE],
offset : usize,
}
assert!(key.len() == 16 || key.len() == 32);
assert!(nonce.len() == 8 || nonce.len() == 12);
- ChaCha20{ state: ChaCha20::expand(key, nonce), output: [0u8; 64], offset: 64 }
+ ChaCha20{ state: ChaCha20::expand(key, nonce), output: [0u8; BLOCK_SIZE], offset: 64 }
}
fn expand(key: &[u8], nonce: &[u8]) -> ChaChaState {
}
}
- // put the the next 64 keystream bytes into self.output
+ // put the the next BLOCK_SIZE keystream bytes into self.output
fn update(&mut self) {
let mut state = self.state;
while i < len {
// If there is no keystream available in the output buffer,
// generate the next block.
- if self.offset == 64 {
+ if self.offset == BLOCK_SIZE {
self.update();
}
// Process the min(available keystream, remaining input length).
- let count = cmp::min(64 - self.offset, len - i);
+ let count = cmp::min(BLOCK_SIZE - self.offset, len - i);
// explicitly assert lengths to avoid bounds checks:
assert!(output.len() >= i + count);
assert!(input.len() >= i + count);
self.offset += count;
}
}
+
+ pub fn process_in_place(&mut self, input_output: &mut [u8]) {
+ let len = input_output.len();
+ let mut i = 0;
+ while i < len {
+ // If there is no keystream available in the output buffer,
+ // generate the next block.
+ if self.offset == BLOCK_SIZE {
+ self.update();
+ }
+
+ // Process the min(available keystream, remaining input length).
+ let count = cmp::min(BLOCK_SIZE - self.offset, len - i);
+ // explicitly assert lengths to avoid bounds checks:
+ assert!(input_output.len() >= i + count);
+ assert!(self.output.len() >= self.offset + count);
+ for j in 0..count {
+ input_output[i + j] ^= self.output[self.offset + j];
+ }
+ i += count;
+ self.offset += count;
+ }
+ }
}
}
#[cfg(not(feature = "fuzztarget"))]
pub fn process(&mut self, input: &[u8], output: &mut [u8]) {
output.copy_from_slice(input);
}
+
+ pub fn process_in_place(&mut self, _input_output: &mut [u8]) {}
}
}
#[cfg(feature = "fuzztarget")]
pub use self::fuzzy_chacha::ChaCha20;
+pub(crate) struct ChaChaReader<'a, R: io::Read> {
+ pub chacha: &'a mut ChaCha20,
+ pub read: R,
+}
+impl<'a, R: io::Read> io::Read for ChaChaReader<'a, R> {
+ fn read(&mut self, dest: &mut [u8]) -> Result<usize, io::Error> {
+ let res = self.read.read(dest)?;
+ if res > 0 {
+ self.chacha.process_in_place(&mut dest[0..res]);
+ }
+ Ok(res)
+ }
+}
+
#[cfg(test)]
mod test {
use std::iter::repeat;