def __init__(self, master_key: BIP32, utxos: List[scanner.Utxo],
address: str, amount_in_sat: int):
"""
Craft and sign a transaction that spends all the UTXOs and sends the requested funds to a specific address.
"""
output_script = scripts.build_output_script_from_address(address)
if output_script is None:
raise ValueError(
'The address is invalid or the format isn\'t recognized.')
if amount_in_sat < NON_SEGWIT_DUST:
raise ValueError('Not enough funds to create a sweep transaction.')
self.outputs = [(amount_in_sat, output_script)]
self.inputs = []
for index in range(len(utxos)):
utxo = utxos[index]
# Build the inputs for signing: they should all have empty scripts, save for the input that we are signing,
# which should have the output script of a P2PKH output.
pubkey = master_key.get_pubkey_from_path(utxo.path.to_list())
script = scripts.ScriptType.LEGACY.build_output_script(pubkey)
inputs = [(u, script if u == utxo else b'', []) for u in utxos]
if utxo.script_type == scripts.ScriptType.LEGACY:
# If this is a legacy input, then the transaction digest is just the wire format serialization.
tx = _serialize_tx(inputs, self.outputs, include_witness=False)
else:
# If this is a segwit input (native or not), then the transaction digest is the one defined in BIP143.
tx = _serialize_tx_for_segwit_signing(index, inputs,
self.outputs)
# To produce the final message digest we need to append the sig-hash type, and double sha256 the message.
tx.extend(SIGHASH_ALL.to_bytes(4, 'little'))
hash = scripts.sha256(scripts.sha256(bytes(tx)))
privkey = master_key.get_privkey_from_path(utxo.path.to_list())
signature = coincurve.PrivateKey(privkey).sign(hash, hasher=None)
extended_signature = bytearray(signature)
extended_signature.append(SIGHASH_ALL)
extended_signature = bytes(extended_signature)
self.inputs.append(
(utxo,
utxo.script_type.build_input_script(pubkey,
extended_signature),
utxo.script_type.build_witness(pubkey, extended_signature)))
