From 563c01754d39c459b5b03c6e057eef94f0cb0619 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Tue, 16 Jan 2024 19:53:39 +0000 Subject: [PATCH] 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. --- lightning/src/crypto/chacha20.rs | 9 ++++----- lightning/src/sign/mod.rs | 5 ++++- 2 files changed, 8 insertions(+), 6 deletions(-) diff --git a/lightning/src/crypto/chacha20.rs b/lightning/src/crypto/chacha20.rs index a4df620df..81e4761c0 100644 --- a/lightning/src/crypto/chacha20.rs +++ b/lightning/src/crypto/chacha20.rs @@ -152,15 +152,14 @@ 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 @@ -585,7 +584,7 @@ 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 8ad34f2d6..ea418edb6 100644 --- a/lightning/src/sign/mod.rs +++ b/lightning/src/sign/mod.rs @@ -2507,7 +2507,10 @@ impl EntropySource for RandomBytes { let index = self.index.next(); let mut nonce = [0u8; 16]; nonce[..8].copy_from_slice(&index.to_be_bytes()); - ChaCha20::get_single_block(&self.seed, &nonce) + let block = ChaCha20::get_single_block(&self.seed, &nonce); + let mut half_block = [0; 32]; + half_block.copy_from_slice(&block[..32]); + half_block } } -- 2.39.5