tverifier: further sanity checks for SPV verification. - electrum - Electrum Bitcoin wallet
(HTM) git clone https://git.parazyd.org/electrum
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---
(DIR) commit 9b82321fc083f3fb4728d9f3785a04861a617011
(DIR) parent 5bf854edcb15906fd6eb6bb707eb5a89f349b73d
(HTM) Author: SomberNight <somber.night@protonmail.com>
Date: Fri, 5 Jul 2019 18:39:40 +0200
verifier: further sanity checks for SPV verification.
Thanks to @JeremyRand
Diffstat:
M electrum/verifier.py | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
---
(DIR) diff --git a/electrum/verifier.py b/electrum/verifier.py
t@@ -142,13 +142,20 @@ class SPV(NetworkJobOnDefaultServer):
try:
h = hash_decode(tx_hash)
merkle_branch_bytes = [hash_decode(item) for item in merkle_branch]
- int(leaf_pos_in_tree) # raise if invalid
+ leaf_pos_in_tree = int(leaf_pos_in_tree) # raise if invalid
except Exception as e:
raise MerkleVerificationFailure(e)
-
- for i, item in enumerate(merkle_branch_bytes):
- h = sha256d(item + h) if ((leaf_pos_in_tree >> i) & 1) else sha256d(h + item)
+ if leaf_pos_in_tree < 0:
+ raise MerkleVerificationFailure('leaf_pos_in_tree must be non-negative')
+ index = leaf_pos_in_tree
+ for item in merkle_branch_bytes:
+ if len(item) != 32:
+ raise MerkleVerificationFailure('all merkle branch items have to 32 bytes long')
+ h = sha256d(item + h) if (index & 1) else sha256d(h + item)
+ index >>= 1
cls._raise_if_valid_tx(bh2u(h))
+ if index != 0:
+ raise MerkleVerificationFailure(f'leaf_pos_in_tree too large for branch')
return hash_encode(h)
@classmethod
t@@ -192,6 +199,8 @@ def verify_tx_is_in_block(tx_hash: str, merkle_branch: Sequence[str],
if not block_header:
raise MissingBlockHeader("merkle verification failed for {} (missing header {})"
.format(tx_hash, block_height))
+ if len(merkle_branch) > 30:
+ raise MerkleVerificationFailure(f"merkle branch too long: {len(merkle_branch)}")
calc_merkle_root = SPV.hash_merkle_root(merkle_branch, tx_hash, leaf_pos_in_tree)
if block_header.get('merkle_root') != calc_merkle_root:
raise MerkleRootMismatch("merkle verification failed for {} ({} != {})".format(