Define a BLOCK_SIZE constant for chacha20

diff --git a/lightning/src/util/chacha20.rs b/lightning/src/util/chacha20.rs
index 09e9a847598e10d51071ab1e3aa2d805d1f15860..8a8205f8dac593b6b41bd71369f2e749c85261f2 100644 (file)
--- a/lightning/src/util/chacha20.rs
+++ b/lightning/src/util/chacha20.rs
@@ -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);