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bip360: consistency changes to p2mr core functions

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Standardizes all P2MR-specific functions to use bytes uniformly for
input/output. Hex conversions are now confined to two boundaries:
reading `script` field out of ScriptTree input, and comparing against
hex-encoded test vector data in `run_single_test`.

bech32 functions and s2w are left unchanged.
This commit is contained in:
notmike
2026-06-26 23:03:50 -06:00
parent 64d068e9d1
commit 94b0f9db4c
1 changed files with 25 additions and 23 deletions
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48
bip-0360/ref-impl/python/p2mr.py
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@@ -75,35 +75,33 @@ def serialize_varbytes(b: bytes) -> bytes:
#
# P2MR-specific Functions
#
def tapleaf_hash(script: str, tapleaf_ver: str = "c0") -> str:
def tapleaf_hash(script: bytes, tapleaf_ver: int = 0xc0) -> bytes:
"""Hash function for tree leaves"""
if not script:
raise ValueError("tapleaf_hash: script is required")
leaf = h2b(tapleaf_ver) + serialize_varbytes(h2b(script))
return tagged_hash("TapLeaf", leaf).hex()
leaf = bytes([tapleaf_ver]) + serialize_varbytes(script)
return tagged_hash("TapLeaf", leaf)
def tapbranch_hash(left: str, right: str) -> bytes:
def tapbranch_hash(left: bytes, right: bytes) -> bytes:
"""Hash function for tree branches"""
return tagged_hash("TapBranch", b"".join(sorted((h2b(left), h2b(right)))))
return tagged_hash("TapBranch", b"".join(sorted((left, right))))
def compute_merkle_root(tree: ScriptTree) -> str:
def compute_merkle_root(tree: ScriptTree) -> bytes:
"""Recursively compute script tree merkle root"""
if isinstance(tree, dict): # Leaf
version = f"{tree['leafVersion']:x}"
script = tree["script"]
version = tree["leafVersion"]
script = h2b(tree["script"])
return tapleaf_hash(script=script, tapleaf_ver=version)
elif isinstance(tree, list): # Branch
# Script trees are treated as strictly binary trees; each branch node should have
# Script trees are treated strictly as binary trees; each branch node should have
# exactly 2 children. This isn't a general n-ary fold, and combining
# more than 2 children sequentially would not produce a valid
# P2MR merkle root. It would also break here on a type mismatch.
# `tapbranch_hash` returns bytes, not the hex str this loop expects.
# more than 2 children sequentially would not produce a valid P2MR merkle root.
assert len(tree) == 2, f"expected binary branch, got {len(tree)} children"
left, right = compute_merkle_root(tree[0]), compute_merkle_root(tree[1])
return tapbranch_hash(left, right).hex()
return tapbranch_hash(left, right)
else: # badbadnotgood
raise ValueError("Invalid tree node")
@@ -128,7 +126,7 @@ def compute_control_block(path: int, tree: ScriptTree) -> bytes:
assert len(tree) == 2
sibling = tree[(path & 1) ^ 1]
tree = tree[(path & 1)]
control_block = h2b(compute_merkle_root(sibling)) + control_block
control_block = compute_merkle_root(sibling) + control_block
path >>= 1
assert isinstance(tree, dict)
@@ -263,15 +261,15 @@ def encode(hrp, witver, witprog):
#
# BIP-360 Test Code
#
def collect_leaf_hashes(tree: ScriptTree) -> List[str]:
def collect_leaf_hashes(tree: ScriptTree) -> List[bytes]:
"""Recursively collect leaf hashes in order (for verification)"""
if isinstance(tree, dict): # Leaf
version = f"{tree['leafVersion']:x}"
script = tree["script"]
version = tree["leafVersion"]
script = h2b(tree["script"])
return [tapleaf_hash(script=script, tapleaf_ver=version)]
elif isinstance(tree, list): # Branch: recurse on children
hashes: List[str] = []
hashes: List[bytes] = []
for sub in tree:
hashes.extend(collect_leaf_hashes(sub))
return hashes
@@ -295,13 +293,13 @@ def walk_script_tree_paths(
return lchild_paths + rchild_paths
def collect_control_blocks(script_tree: ScriptTree) -> List[str]:
def collect_control_blocks(script_tree: ScriptTree) -> List[bytes]:
"""Return control blocks for all leaves in tree declaration order.
Note: This ordering is for testing purposes. In practice, you would
compute the control block for a specific leaf at spend-time using
`compute_control_block(path, tree)`."""
leaf_node_paths: List[int] = walk_script_tree_paths(script_tree)
return [compute_control_block(path, script_tree).hex() for path in leaf_node_paths]
return [compute_control_block(path, script_tree) for path in leaf_node_paths]
def extract_test_data(v: Dict[str, Any]) -> Dict[str, Any]:
@@ -353,7 +351,9 @@ def run_single_test(v: Dict[str, Any], test_num: int) -> bool:
# General Case: Single- and Multi-Leaf script trees
else:
# test script leaf hashing
derived_leaf_hashes = collect_leaf_hashes(v["script_tree"])
derived_leaf_hashes = [
h.hex() for h in collect_leaf_hashes(v["script_tree"])
]
assert derived_leaf_hashes == v["leaf_hashes"], (
f"leaf hash mismatch:\n"
f" derived: {derived_leaf_hashes}\n"
@@ -362,7 +362,7 @@ def run_single_test(v: Dict[str, Any], test_num: int) -> bool:
print("Leaf Hashes: [\n" + ",\n".join(derived_leaf_hashes) + "\n]")
# test merkle root computation
derived_merkle_root = compute_merkle_root(v["script_tree"])
derived_merkle_root = compute_merkle_root(v["script_tree"]).hex()
assert derived_merkle_root == v["merkle_root"], (
f"merkle root mismatch: "
f"derived={derived_merkle_root}, expected={v['merkle_root']}"
@@ -390,7 +390,9 @@ def run_single_test(v: Dict[str, Any], test_num: int) -> bool:
# test control block derivation
if v["script_path_control_blocks"]:
derived_control_blocks = collect_control_blocks(v["script_tree"])
derived_control_blocks = [
cb.hex() for cb in collect_control_blocks(v["script_tree"])
]
assert derived_control_blocks == v["script_path_control_blocks"], (
f"control blocks mismatch:\n"
f" derived: {derived_control_blocks}\n"