lbry-sdk/lbrynet/extras/wallet/claim_proofs.py

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import six
import struct
import binascii
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from torba.client.hash import double_sha256
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class InvalidProofError(Exception):
pass
def get_hash_for_outpoint(txhash, nout, height_of_last_takeover):
return double_sha256(
double_sha256(txhash) +
double_sha256(str(nout).encode()) +
double_sha256(struct.pack('>Q', height_of_last_takeover))
)
# noinspection PyPep8
def verify_proof(proof, rootHash, name):
previous_computed_hash = None
reverse_computed_name = ''
verified_value = False
for i, node in enumerate(proof['nodes'][::-1]):
found_child_in_chain = False
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to_hash = b''
previous_child_character = None
for child in node['children']:
if child['character'] < 0 or child['character'] > 255:
raise InvalidProofError("child character not int between 0 and 255")
if previous_child_character:
if previous_child_character >= child['character']:
raise InvalidProofError("children not in increasing order")
previous_child_character = child['character']
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to_hash += six.int2byte(child['character'])
if 'nodeHash' in child:
if len(child['nodeHash']) != 64:
raise InvalidProofError("invalid child nodeHash")
to_hash += binascii.unhexlify(child['nodeHash'])[::-1]
else:
if previous_computed_hash is None:
raise InvalidProofError("previous computed hash is None")
if found_child_in_chain is True:
raise InvalidProofError("already found the next child in the chain")
found_child_in_chain = True
reverse_computed_name += chr(child['character'])
to_hash += previous_computed_hash
if not found_child_in_chain:
if i != 0:
raise InvalidProofError("did not find the alleged child")
if i == 0 and 'txhash' in proof and 'nOut' in proof and 'last takeover height' in proof:
if len(proof['txhash']) != 64:
raise InvalidProofError("txhash was invalid: {}".format(proof['txhash']))
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if not isinstance(proof['nOut'], int):
raise InvalidProofError("nOut was invalid: {}".format(proof['nOut']))
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if not isinstance(proof['last takeover height'], int):
raise InvalidProofError(
'last takeover height was invalid: {}'.format(proof['last takeover height']))
to_hash += get_hash_for_outpoint(
binascii.unhexlify(proof['txhash'])[::-1],
proof['nOut'],
proof['last takeover height']
)
verified_value = True
elif 'valueHash' in node:
if len(node['valueHash']) != 64:
raise InvalidProofError("valueHash was invalid")
to_hash += binascii.unhexlify(node['valueHash'])[::-1]
previous_computed_hash = double_sha256(to_hash)
if previous_computed_hash != binascii.unhexlify(rootHash)[::-1]:
raise InvalidProofError("computed hash does not match roothash")
if 'txhash' in proof and 'nOut' in proof:
if not verified_value:
raise InvalidProofError("mismatch between proof claim and outcome")
if 'txhash' in proof and 'nOut' in proof:
if name != reverse_computed_name[::-1]:
raise InvalidProofError("name did not match proof")
if not name.startswith(reverse_computed_name[::-1]):
raise InvalidProofError("name fragment does not match proof")
return True