feat(target_chains/starknet): add merkle tree utils

target_chains/starknet/contracts/src/lib.cairo

@@ -3,3 +3,4 @@ pub mod wormhole;
 pub mod reader;
 pub mod hash;
 pub mod util;
+pub mod merkle_tree;

target_chains/starknet/contracts/src/merkle_tree.cairo

@@ -0,0 +1,70 @@
+use super::hash::{Hasher, HasherImpl};
+use super::reader::{Reader, ReaderImpl, ByteArray};
+use super::util::ONE_SHIFT_96;
+use core::cmp::{min, max};
+
+const MERKLE_LEAF_PREFIX: u8 = 0;
+const MERKLE_NODE_PREFIX: u8 = 1;
+const MERKLE_EMPTY_LEAF_PREFIX: u8 = 2;
+
+#[derive(Copy, Drop, Debug, Serde, PartialEq)]
+pub enum MerkleVerificationError {
+ Reader: super::reader::Error,
+ DigestMismatch,
+}
+
+#[generate_trait]
+impl ResultReaderToMerkleVerification<T> of ResultReaderToMerkleVerificationTrait<T> {
+ fn map_err(self: Result<T, pyth::reader::Error>) -> Result<T, MerkleVerificationError> {
+ match self {
+ Result::Ok(v) => Result::Ok(v),
+ Result::Err(err) => Result::Err(MerkleVerificationError::Reader(err)),
+ }
+ }
+}
+
+fn leaf_hash(mut reader: Reader) -> Result<u256, super::reader::Error> {
+ let mut hasher = HasherImpl::new();
+ hasher.push_u8(MERKLE_LEAF_PREFIX);
+ hasher.push_reader(ref reader)?;
+ let hash = hasher.finalize() / ONE_SHIFT_96;
+ Result::Ok(hash)
+}
+
+fn node_hash(a: u256, b: u256) -> u256 {
+ let mut hasher = HasherImpl::new();
+ hasher.push_u8(MERKLE_NODE_PREFIX);
+ hasher.push_u160(min(a, b));
+ hasher.push_u160(max(a, b));
+ hasher.finalize() / ONE_SHIFT_96
+}
+
+pub fn read_and_verify_proof(
+ root_digest: u256, message: @ByteArray, ref reader: Reader
+) -> Result<(), MerkleVerificationError> {
+ let mut message_reader = ReaderImpl::new(message.clone());
+ let mut current_hash = leaf_hash(message_reader.clone()).map_err()?;
+
+ let proof_size = reader.read_u8().map_err()?;
+ let mut i = 0;
+
+ let mut result = Result::Ok(());
+ while i < proof_size {
+ match reader.read_u160().map_err() {
+ Result::Ok(sibling_digest) => {
+ current_hash = node_hash(current_hash, sibling_digest);
+ },
+ Result::Err(err) => {
+ result = Result::Err(err);
+ break;
+ },
+ }
+ i += 1;
+ };
+ result?;
+
+ if root_digest != current_hash {
+ return Result::Err(MerkleVerificationError::DigestMismatch);
+ }
+ Result::Ok(())
+}