def verify(self):
'''Returns whether this proof is valid'''
current = self.tx_hash[::-1]
path = merkle_path(self.index, 2**len(self.merkle_proof))
for i, proof_hash in enumerate(self.merkle_proof):
if path[i] % 2 == 1:
current = merkle_parent(proof_hash, current)
else:
current = merkle_parent(current, proof_hash)
return current[::-1] == self.merkle_root
def verify(self):
'''Returns whether this proof is valid'''
# current hash starts with self.tx_hash, reversed
current = self.tx_hash[::-1]
# Get the Merkle Path for the index and 2**len(merkle_proof)
path = merkle_path(self.index, 2**len(self.merkle_proof))
# Loop through Merkle Path and proof hashes
for proof_hash, index_at_level in zip(self.merkle_proof, path):
# if index_at_level is odd, proof_hash goes on left
if index_at_level % 2 == 1:
# current hash becomes merkle parent of proof_hash and current
current = merkle_parent(proof_hash, current)
# if index_at_level is even, proof_hash goes on right
else:
# current hash becomes merkle parent of current and proof_hash
current = merkle_parent(current, proof_hash)
# if final result reversed is equal to merkle_root, return True
return current[::-1] == self.merkle_root
def create_merkle_proof(self, tx_hash):
# if self.merkle_tree is empty, go and calculate the merkle tree
if self.merkle_tree is None:
self.calculate_merkle_tree()
# find the index of this tx_hash
index = self.tx_hashes.index(tx_hash)
# Get the Merkle Path
path = merkle_path(index, len(self.tx_hashes))
# initialize merkle_proof list
proof_hashes = []
# Loop over the items in the Merkle Path
for level, index_at_level in enumerate(path):
# Find the partner index (-1 for odd, +1 for even)
if index_at_level % 2 == 1:
partner_index = index_at_level - 1
else:
partner_index = index_at_level + 1
# add partner to merkle_proof list
proof_hashes.append(self.merkle_tree[level][partner_index])
# Return a Proof instance
return Proof(self.merkle_root, tx_hash, index, proof_hashes)
def create_merkle_proof(self, tx_hash):
if self.tx_hashes is None:
return None
elif self.merkle_tree is None:
self.calculate_merkle_tree()
index = self.merkle_tree[0].index(tx_hash[::-1])
current = self.merkle_tree[0][index]
proof_hashes = []
for level, level_index in enumerate(
merkle_path(index, len(self.tx_hashes))):
if level_index % 2 == 0:
partner = self.merkle_tree[level][level_index + 1]
current = merkle_parent(current, partner)
else:
partner = self.merkle_tree[level][level_index - 1]
current = merkle_parent(partner, current)
proof_hashes.append(partner)
# sanity check
if current != self.merkle_tree[-1][0]:
raise RuntimeError('merkle tree looks invalid')
return Proof(self.merkle_root, tx_hash, index, proof_hashes)
def test_merkle_path(self):
i = 7
total = 11
want = [7, 3, 1, 0]
self.assertEqual(merkle_path(i, total), want)