Make `ChaCha20::get_single_block` return a full, single block

While the current uses for `ChaCha20::get_single_block` only
actually want 32 bytes, a ChaCha20 block is 64 bytes, and future
uses may want another 32 bytes, so we can go ahead and return the
whole block when asked for one.

diff --git a/lightning/src/crypto/chacha20.rs b/lightning/src/crypto/chacha20.rs
index d6fd3a7dee0013c1bbbfb466737e3fae16a415da..bd9bcc562d3b2088ad5cdfd713cb0bac5fb5e8c3 100644 (file)
--- a/lightning/src/crypto/chacha20.rs
+++ b/lightning/src/crypto/chacha20.rs
@@ -150,11 +150,10 @@ mod real_chacha {
                }
 
                /// Get one block from a ChaCha stream.
-               pub fn get_single_block(key: &[u8; 32], nonce: &[u8; 16]) -> [u8; 32] {
+               pub fn get_single_block(key: &[u8; 32], nonce: &[u8; 16]) -> [u8; 64] {
                        let mut chacha = ChaCha20 { state: ChaCha20::expand(key, nonce), output: [0u8; BLOCK_SIZE], offset: 64 };
-                       let mut chacha_bytes = [0; 32];
-                       chacha.process_in_place(&mut chacha_bytes);
-                       chacha_bytes
+                       chacha.update();
+                       chacha.output
                }
 
                /// Encrypts `src` into `dest` using a single block from a ChaCha stream. Passing `dest` as
@@ -633,7 +632,7 @@ mod test {
                let mut chacha20 = ChaCha20::new(&key, nonce_12bytes);
                // Seek its counter to the block at counter_pos.
                chacha20.seek_to_block(u32::from_le_bytes(counter_pos.try_into().unwrap()));
-               let mut block_bytes = [0; 32];
+               let mut block_bytes = [0; 64];
                chacha20.process_in_place(&mut block_bytes);
 
                assert_eq!(ChaCha20::get_single_block(&key, &nonce_16bytes), block_bytes);

diff --git a/lightning/src/sign/mod.rs b/lightning/src/sign/mod.rs
index c4bb6fb8020ed8d5d1ee3c32a862f44b19a82737..4029d7675e81379108f4180e18933f6c816df970 100644 (file)
--- a/lightning/src/sign/mod.rs
+++ b/lightning/src/sign/mod.rs
@@ -1072,7 +1072,10 @@ impl EntropySource for InMemorySigner {
                let index = self.rand_bytes_index.get_increment();
                let mut nonce = [0u8; 16];
                nonce[..8].copy_from_slice(&index.to_be_bytes());
-               ChaCha20::get_single_block(&self.rand_bytes_unique_start, &nonce)
+               let block = ChaCha20::get_single_block(&self.rand_bytes_unique_start, &nonce);
+               let mut half_block = [0; 32];
+               half_block.copy_from_slice(&block[..32]);
+               half_block
        }
 }
 
@@ -1634,7 +1637,10 @@ impl EntropySource for KeysManager {
                let index = self.rand_bytes_index.get_increment();
                let mut nonce = [0u8; 16];
                nonce[..8].copy_from_slice(&index.to_be_bytes());
-               ChaCha20::get_single_block(&self.rand_bytes_unique_start, &nonce)
+               let block = ChaCha20::get_single_block(&self.rand_bytes_unique_start, &nonce);
+               let mut half_block = [0; 32];
+               half_block.copy_from_slice(&block[..32]);
+               half_block
        }
 }