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Define a BLOCK_SIZE constant for chacha20

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This commit is contained in:
Matt Corallo 2020-02-10 18:32:57 -05:00
parent 65a2bcf46c
commit bec0a260e8
1 changed files with 9 additions and 7 deletions
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16
lightning/src/util/chacha20.rs
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@ -56,6 +56,8 @@ mod real_chacha {
}
}
const BLOCK_SIZE: usize = 64;
#[derive(Clone,Copy)]
struct ChaChaState {
a: u32x4,
@ -67,7 +69,7 @@ mod real_chacha {
#[derive(Copy)]
pub struct ChaCha20 {
state : ChaChaState,
output : [u8; 64],
output : [u8; BLOCK_SIZE],
offset : usize,
}
@ -135,7 +137,7 @@ mod real_chacha {
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 {
@ -197,7 +199,7 @@ mod real_chacha {
}
}
// 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;
@ -234,12 +236,12 @@ mod real_chacha {
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);
@ -258,12 +260,12 @@ mod real_chacha {
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!(input_output.len() >= i + count);
assert!(self.output.len() >= self.offset + count);