--- /dev/null
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Tagged hashes for use in signature calculation and verification.
+
+use bitcoin::hashes::{Hash, HashEngine, sha256};
+use crate::io;
+use crate::util::ser::{BigSize, Readable};
+
+use crate::prelude::*;
+
+/// Valid type range for signature TLV records.
+const SIGNATURE_TYPES: core::ops::RangeInclusive<u64> = 240..=1000;
+
+/// Computes a merkle root hash for the given data, which must be a well-formed TLV stream
+/// containing at least one TLV record.
+fn root_hash(data: &[u8]) -> sha256::Hash {
+ let mut tlv_stream = TlvStream::new(&data[..]).peekable();
+ let nonce_tag = tagged_hash_engine(sha256::Hash::from_engine({
+ let mut engine = sha256::Hash::engine();
+ engine.input("LnNonce".as_bytes());
+ engine.input(tlv_stream.peek().unwrap().record_bytes);
+ engine
+ }));
+ let leaf_tag = tagged_hash_engine(sha256::Hash::hash("LnLeaf".as_bytes()));
+ let branch_tag = tagged_hash_engine(sha256::Hash::hash("LnBranch".as_bytes()));
+
+ let mut leaves = Vec::new();
+ for record in tlv_stream {
+ if !SIGNATURE_TYPES.contains(&record.r#type) {
+ leaves.push(tagged_hash_from_engine(leaf_tag.clone(), &record));
+ leaves.push(tagged_hash_from_engine(nonce_tag.clone(), &record.type_bytes));
+ }
+ }
+
+ // Calculate the merkle root hash in place.
+ let num_leaves = leaves.len();
+ for level in 0.. {
+ let step = 2 << level;
+ let offset = step / 2;
+ if offset >= num_leaves {
+ break;
+ }
+
+ let left_branches = (0..num_leaves).step_by(step);
+ let right_branches = (offset..num_leaves).step_by(step);
+ for (i, j) in left_branches.zip(right_branches) {
+ leaves[i] = tagged_branch_hash_from_engine(branch_tag.clone(), leaves[i], leaves[j]);
+ }
+ }
+
+ *leaves.first().unwrap()
+}
+
+fn tagged_hash<T: AsRef<[u8]>>(tag: sha256::Hash, msg: T) -> sha256::Hash {
+ let engine = tagged_hash_engine(tag);
+ tagged_hash_from_engine(engine, msg)
+}
+
+fn tagged_hash_engine(tag: sha256::Hash) -> sha256::HashEngine {
+ let mut engine = sha256::Hash::engine();
+ engine.input(tag.as_ref());
+ engine.input(tag.as_ref());
+ engine
+}
+
+fn tagged_hash_from_engine<T: AsRef<[u8]>>(mut engine: sha256::HashEngine, msg: T) -> sha256::Hash {
+ engine.input(msg.as_ref());
+ sha256::Hash::from_engine(engine)
+}
+
+fn tagged_branch_hash_from_engine(
+ mut engine: sha256::HashEngine, leaf1: sha256::Hash, leaf2: sha256::Hash,
+) -> sha256::Hash {
+ if leaf1 < leaf2 {
+ engine.input(leaf1.as_ref());
+ engine.input(leaf2.as_ref());
+ } else {
+ engine.input(leaf2.as_ref());
+ engine.input(leaf1.as_ref());
+ };
+ sha256::Hash::from_engine(engine)
+}
+
+/// [`Iterator`] over a sequence of bytes yielding [`TlvRecord`]s. The input is assumed to be a
+/// well-formed TLV stream.
+struct TlvStream<'a> {
+ data: io::Cursor<&'a [u8]>,
+}
+
+impl<'a> TlvStream<'a> {
+ fn new(data: &'a [u8]) -> Self {
+ Self {
+ data: io::Cursor::new(data),
+ }
+ }
+}
+
+/// A slice into a [`TlvStream`] for a record.
+struct TlvRecord<'a> {
+ r#type: u64,
+ type_bytes: &'a [u8],
+ // The entire TLV record.
+ record_bytes: &'a [u8],
+}
+
+impl AsRef<[u8]> for TlvRecord<'_> {
+ fn as_ref(&self) -> &[u8] { &self.record_bytes }
+}
+
+impl<'a> Iterator for TlvStream<'a> {
+ type Item = TlvRecord<'a>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if self.data.position() < self.data.get_ref().len() as u64 {
+ let start = self.data.position();
+
+ let r#type = <BigSize as Readable>::read(&mut self.data).unwrap().0;
+ let offset = self.data.position();
+ let type_bytes = &self.data.get_ref()[start as usize..offset as usize];
+
+ let length = <BigSize as Readable>::read(&mut self.data).unwrap().0;
+ let offset = self.data.position();
+ let end = offset + length;
+
+ let _value = &self.data.get_ref()[offset as usize..end as usize];
+ let record_bytes = &self.data.get_ref()[start as usize..end as usize];
+
+ self.data.set_position(end);
+
+ Some(TlvRecord { r#type, type_bytes, record_bytes })
+ } else {
+ None
+ }
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use bitcoin::hashes::{Hash, sha256};
+
+ #[test]
+ fn calculates_merkle_root_hash() {
+ // BOLT 12 test vectors
+ macro_rules! tlv1 { () => { "010203e8" } }
+ macro_rules! tlv2 { () => { "02080000010000020003" } }
+ macro_rules! tlv3 { () => { "03310266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c0351800000000000000010000000000000002" } }
+ assert_eq!(
+ super::root_hash(&hex::decode(tlv1!()).unwrap()),
+ sha256::Hash::from_slice(&hex::decode("b013756c8fee86503a0b4abdab4cddeb1af5d344ca6fc2fa8b6c08938caa6f93").unwrap()).unwrap(),
+ );
+ assert_eq!(
+ super::root_hash(&hex::decode(concat!(tlv1!(), tlv2!())).unwrap()),
+ sha256::Hash::from_slice(&hex::decode("c3774abbf4815aa54ccaa026bff6581f01f3be5fe814c620a252534f434bc0d1").unwrap()).unwrap(),
+ );
+ assert_eq!(
+ super::root_hash(&hex::decode(concat!(tlv1!(), tlv2!(), tlv3!())).unwrap()),
+ sha256::Hash::from_slice(&hex::decode("ab2e79b1283b0b31e0b035258de23782df6b89a38cfa7237bde69aed1a658c5d").unwrap()).unwrap(),
+ );
+ }
+}
projects / rust-lightning / commitdiff