Add an implementation of mutual message exchange

Cargo.toml

@@ -14,6 +14,7 @@ members = [
     "lightning-rapid-gossip-sync",
     "lightning-custom-message",
     "lightning-transaction-sync",
+    "mutual-message-exchange",
     "possiblyrandom",
 ]
 

ci/ci-tests.sh

@@ -46,6 +46,7 @@ WORKSPACE_MEMBERS=(
 	lightning-rapid-gossip-sync
 	lightning-custom-message
 	lightning-transaction-sync
+	mutual-message-exchange
 	possiblyrandom
 )
 

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
@@ -342,8 +341,6 @@ pub use self::fuzzy_chacha::ChaCha20;
 mod test {
 	use core::iter::repeat;
 
-	use crate::prelude::*;
-
 	use super::ChaCha20;
 
 	#[test]
@@ -587,7 +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);

lightning/src/crypto/poly1305.rs

@@ -9,8 +9,6 @@
 
 use core::cmp::min;
 
-use crate::prelude::*;
-
 #[derive(Clone, Copy)]
 pub struct Poly1305 {
 	r: [u32; 5],

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
 	}
 }
 

mutual-message-exchange/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "mutual-message-exchange"
+version = "0.1.0"
+authors = ["Matt Corallo"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/lightningdevkit/rust-lightning/"
+description = """
+An implementation of a trivial mutual authentication scheme where a message can be exchanged iff two parties mutually trust each other (out of individual trusted-keys lists).
+"""
+edition = "2021"
+
+[package.metadata.docs.rs]
+rustdoc-args = ["--cfg", "docsrs"]
+
+[features]
+
+[dependencies]
+bitcoin_hashes = { version = "^0.12.0", default-features = false }
+secp256k1 = { version = "^0.27.0", default-features = false, features = ["alloc"] }
+
+[dev-dependencies]

mutual-message-exchange/src/chacha20.rs

@@ -0,0 +1 @@
+../../lightning/src/crypto/chacha20.rs

mutual-message-exchange/src/chacha20poly1305rfc.rs

@@ -0,0 +1 @@
+../../lightning/src/crypto/chacha20poly1305rfc.rs