def _get_blinding_factors(self, txdetails, wally_tx):
utxos = txdetails['used_utxos'] or txdetails['old_used_utxos']
for i, o in enumerate(txdetails['transaction_outputs']):
o['wally_index'] = i
blinded_outputs = [
o for o in txdetails['transaction_outputs'] if not o['is_fee']
]
for output in blinded_outputs:
# TODO: the derivation dance
# the following values are in display order, reverse them when converting to bytes
output['assetblinder'] = os.urandom(32).hex()
output['amountblinder'] = os.urandom(32).hex()
endpoints = utxos + blinded_outputs
values = [endpoint['satoshi'] for endpoint in endpoints]
abfs = b''.join(
bytes.fromhex(endpoint['assetblinder'])[::-1]
for endpoint in endpoints)
vbfs = b''.join(
bytes.fromhex(endpoint['amountblinder'])[::-1]
for endpoint in endpoints[:-1])
final_vbf = wally.asset_final_vbf(values, len(utxos), abfs, vbfs)
blinded_outputs[-1]['amountblinder'] = final_vbf[::-1].hex()
for o in blinded_outputs:
asset_commitment = wally.asset_generator_from_bytes(
bytes.fromhex(o['asset_id'])[::-1],
bytes.fromhex(o['assetblinder'])[::-1])
value_commitment = wally.asset_value_commitment(
o['satoshi'],
bytes.fromhex(o['amountblinder'])[::-1], asset_commitment)
o['asset_commitment'] = asset_commitment.hex()
o['value_commitment'] = value_commitment.hex()
# Write the commitments into the wally tx for signing
wally.tx_set_output_asset(wally_tx, o['wally_index'],
asset_commitment)
wally.tx_set_output_value(wally_tx, o['wally_index'],
value_commitment)
retval = {}
for key in [
'assetblinders', 'amountblinders', 'asset_commitments',
'value_commitments'
]:
# gdk expects to get an empty entry for the fee output too, hence this is over the
# transaction outputs, not just the blinded outputs (fee will just have empty
# strings)
retval[key] = [
o.get(key[:-1], '') for o in txdetails['transaction_outputs']
]
return retval
total_in = sum(values_in)
output_values = [
total_in - fee,
]
confidential_output_addresses = [
destination_address,
]
output_asset_ids = asset_ids_in[:wally.ASSET_TAG_LEN]
# end-define_outputs
# start-blinding_factors
num_inputs = len(values_in)
num_outputs = 1
abfs_out = os.urandom(32 * num_outputs)
vbfs_out = os.urandom(32 * (num_outputs - 1))
vbfs_out += wally.asset_final_vbf(values_in + output_values, num_inputs,
abfs_in + abfs_out, vbfs_in + vbfs_out)
# end-blinding_factors
# start-decompose_address
blinding_pubkeys = [
wally.confidential_addr_to_ec_public_key(confidential_address,
address_prefix)
for confidential_address in confidential_output_addresses
]
non_confidential_addresses = [
wally.confidential_addr_to_addr(confidential_address, address_prefix)
for confidential_address in confidential_output_addresses
]
script_pubkeys = [
def sign_tx(self, details: Dict) -> Dict:
txhex = details['transaction']['transaction']
signing_inputs = details['signing_inputs']
use_ae_protocol = details['use_ae_protocol']
transaction_outputs = details['transaction_outputs']
logging.debug('sign liquid txn with %d inputs and %d outputs',
len(signing_inputs), len(transaction_outputs))
def _map_input(input: Dict) -> Dict:
is_segwit = input['address_type'] in ['p2wsh', 'csv', 'p2sh-p2wpkh', 'p2wpkh']
mapped = { 'is_witness': is_segwit,
'path': input['user_path'],
'value_commitment': bytes.fromhex(input['commitment']),
'script': bytes.fromhex(input['prevout_script'])}
# Additional fields to pass through if using the Anti-Exfil protocol
if use_ae_protocol:
mapped['ae_host_commitment'] = bytes.fromhex(input['ae_host_commitment'])
mapped['ae_host_entropy'] = bytes.fromhex(input['ae_host_entropy'])
return mapped
# Get inputs and change outputs in form Jade expects
jade_inputs = list(map(_map_input, signing_inputs))
change = list(map(self._map_change_output, transaction_outputs))
# Calculate the hash-prevout from the inputs
values, abfs, vbfs, input_prevouts = [], [], [], []
for input in signing_inputs:
# Get values, abfs and vbfs from inputs (needed to compute the final output vbf)
values.append(input['satoshi'])
abfs.append(bytes.fromhex(input['assetblinder'])[::-1])
vbfs.append(bytes.fromhex(input['amountblinder'])[::-1])
# Get the input prevout txid and index for hashing later
input_prevouts.append(bytes.fromhex(input['txhash'])[::-1])
input_prevouts.append(input['pt_idx'].to_bytes(4, byteorder='little'))
hash_prevouts = bytes(wally.sha256d(b''.join(input_prevouts)))
# Get the trusted commitments from Jade
idx, trusted_commitments = 0, []
blinded_outputs = transaction_outputs[:-1] # Assume last output is fee
for output in blinded_outputs[:-1]: # Not the last blinded output as we calculate the vbf for that
commitments = self._get_trusted_commitments(idx, output, hash_prevouts, None)
trusted_commitments.append(commitments)
values.append(output['satoshi'])
abfs.append(commitments['abf'])
vbfs.append(commitments['vbf'])
idx += 1
# Calculate the final vbf
values.append(blinded_outputs[idx]['satoshi'])
finalAbf = self.jade.get_blinding_factor(hash_prevouts, idx, 'ASSET')
abfs.append(finalAbf)
final_vbf = bytes(wally.asset_final_vbf(values, len(signing_inputs), b''.join(abfs), b''.join(vbfs)))
# Get the final trusted commitments from Jade (with the calculated vbf)
commitments = self._get_trusted_commitments(idx, blinded_outputs[idx], hash_prevouts, final_vbf)
trusted_commitments.append(commitments)
# Add a 'null' commitment for the final (fee) output
trusted_commitments.append(None)
# Sign!
txn = bytes.fromhex(txhex)
signatures = self.jade.sign_liquid_tx(self.network, txn, jade_inputs, trusted_commitments, change, use_ae_protocol)
assert len(signatures) == len(signing_inputs)
result = {}
if use_ae_protocol:
# If using the Anti-Exfil protocol, the response is a list of
# (signer_commitment, signature), so need to unzip the lists
signer_commitments, signatures = zip(*signatures)
signer_commitments = list(map(bytes.hex, signer_commitments))
result['signer_commitments'] = signer_commitments
signatures = list(map(bytes.hex, signatures))
result['signatures'] = signatures
# Poke the blinding factors into the results structure
self._populate_result(trusted_commitments, result)
logging.debug('resolving {}'.format(result))
return json.dumps(result)
def sign_tx(self, required_data):
signing_inputs = required_data['signing_inputs']
transaction_outputs = required_data['transaction_outputs']
signing_transactions = required_data['signing_transactions']
signing_address_types = required_data['signing_address_types']
scripts = []
for in_ in signing_inputs:
service_xpub = deserialize(in_['service_xpub'])
user_xpub = deserialize(self.as_xpub(in_['user_path'][:-1]))
pointer = in_['pointer']
redeem_script = proto.MultisigRedeemScriptType(
nodes=[user_xpub, service_xpub],
address_n=[pointer],
signatures=[b'', b''],
m=2,
csv=in_['subtype'])
scripts.append(redeem_script)
ins = []
for i, txin in enumerate(signing_inputs):
in_ = proto.TxInputType(
address_n=txin['user_path'],
prev_hash=h2b(txin['txhash']),
prev_index=txin['pt_idx'],
script_type=proto.InputScriptType.SPENDP2SHWITNESS,
multisig=scripts[i],
amount=txin['satoshi'],
sequence=txin['sequence'])
in_.confidential = proto.TxConfidentialAsset(
asset=h2b(txin['asset_id'])[::-1],
amount_blind=h2b(txin['vbf']),
asset_blind=h2b(txin['abf']))
ins.append(in_)
values = []
in_vbfs = []
in_abfs = []
for txin in signing_inputs:
in_vbfs.append(h2b(txin['vbf']))
in_abfs.append(h2b(txin['abf']))
values.append(txin['satoshi'])
out_vbfs = []
out_abfs = []
for i, txout in enumerate(transaction_outputs):
if txout['is_fee']:
continue
out_vbfs.append(
os.urandom(32)) # TODO: check if HW is going to generate these
out_abfs.append(
os.urandom(32)) # TODO: check if HW is going to generate these
values.append(txout['satoshi'])
abfs = in_abfs + out_abfs
vbfs = in_vbfs + out_vbfs[:-1]
final_vbf = wally.asset_final_vbf(values, len(signing_inputs),
b''.join(abfs), b''.join(vbfs))
out_vbfs[-1] = final_vbf
outs = []
for i, txout in enumerate(transaction_outputs):
if txout['is_fee']:
out = proto.TxOutputType(address='', amount=txout['satoshi'])
out.confidential = proto.TxConfidentialAsset(
asset=h2b(txout['asset_id'])[::-1])
else:
out = proto.TxOutputType(
address=txout['address'],
amount=txout['satoshi'],
script_type=proto.OutputScriptType.PAYTOADDRESS)
out.confidential = proto.TxConfidentialAsset(
asset=h2b(txout['asset_id'])[::-1],
amount_blind=out_vbfs[i],
asset_blind=out_abfs[i],
nonce_privkey=h2b(txout['eph_keypair_sec']))
outs.append(out)
signatures, serialized_tx = btc.sign_tx(
self.client,
'Elements',
ins,
outs,
prev_txes=None,
details=proto.SignTx(version=2,
lock_time=required_data['transaction']
['transaction_locktime']))
# with open('tx.txt', 'w') as f:
# f.write(serialized_tx.hex())
asset_commitments = []
value_commitments = []
tx = wally.tx_from_bytes(
serialized_tx,
wally.WALLY_TX_FLAG_USE_WITNESS | wally.WALLY_TX_FLAG_USE_ELEMENTS)
for i in range(wally.tx_get_num_outputs(tx)):
asset_commitments.append(wally.tx_get_output_asset(tx, i))
value_commitments.append(wally.tx_get_output_value(tx, i))
out_abfs.append(b'\x00' *
32) # FIXME: GDK enforcing blinding factors for fee
out_vbfs.append(b'\x00' * 32)
return json.dumps({
'signatures': [sig.hex() + '01' for sig in signatures],
'vbfs': [vbf.hex() for vbf in out_vbfs],
'abfs': [abf.hex() for abf in out_abfs],
'asset_commitments':
[commitment.hex() for commitment in asset_commitments],
'value_commitments':
[commitment.hex() for commitment in value_commitments]
})