def __init__(self, tx: SignTx, keychain: seed.Keychain,
coin: coininfo.CoinInfo) -> None:
self.coin = coin
self.tx = helpers.sanitize_sign_tx(tx, coin)
self.keychain = keychain
# checksum of multisig inputs, used to validate change-output
self.multisig_fingerprint = MultisigFingerprintChecker()
# common prefix of input paths, used to validate change-output
self.wallet_path = WalletPathChecker()
# set of indices of inputs which are segwit
self.segwit = set() # type: Set[int]
# amounts
self.total_in = 0 # sum of input amounts
self.bip143_in = 0 # sum of segwit input amounts
self.total_out = 0 # sum of output amounts
self.change_out = 0 # change output amount
self.weight = tx_weight.TxWeightCalculator(tx.inputs_count,
tx.outputs_count)
# transaction and signature serialization
self.serialized_tx = writers.empty_bytearray(
_MAX_SERIALIZED_CHUNK_SIZE)
self.tx_req = TxRequest()
self.tx_req.details = TxRequestDetailsType()
self.tx_req.serialized = TxRequestSerializedType()
self.tx_req.serialized.serialized_tx = self.serialized_tx
# h_confirmed is used to make sure that the inputs and outputs streamed for
# confirmation in Steps 1 and 2 are the same as the ones streamed for signing
# legacy inputs in Step 4.
self.h_confirmed = self.create_hash_writer() # not a real tx hash
# BIP-0143 transaction hashing
self.init_hash143()
async def sign_tx(tx: SignTx, keychain: seed.Keychain):
tx = helpers.sanitize_sign_tx(tx)
progress.init(tx.inputs_count, tx.outputs_count)
# Phase 1
h_first, hash143, segwit, authorized_in, wallet_path = await check_tx_fee(
tx, keychain)
# Phase 2
# - sign inputs
# - check that nothing changed
coin = coins.by_name(tx.coin_name)
tx_ser = TxRequestSerializedType()
txo_bin = TxOutputBinType()
tx_req = TxRequest()
tx_req.details = TxRequestDetailsType()
tx_req.serialized = None
if coin.decred:
prefix_hash = hash143.prefix_hash()
for i_sign in range(tx.inputs_count):
progress.advance()
txi_sign = None
key_sign = None
key_sign_pub = None
if segwit[i_sign]:
# STAGE_REQUEST_SEGWIT_INPUT
txi_sign = await helpers.request_tx_input(tx_req, i_sign)
if not input_is_segwit(txi_sign):
raise SigningError(FailureType.ProcessError,
"Transaction has changed during signing")
input_check_wallet_path(txi_sign, wallet_path)
key_sign = keychain.derive(txi_sign.address_n, coin.curve_name)
key_sign_pub = key_sign.public_key()
txi_sign.script_sig = input_derive_script(coin, txi_sign,
key_sign_pub)
w_txi = writers.empty_bytearray(7 + len(txi_sign.prev_hash) + 4 +
len(txi_sign.script_sig) + 4)
if i_sign == 0: # serializing first input => prepend headers
writers.write_bytes(w_txi, get_tx_header(coin, tx, True))
writers.write_tx_input(w_txi, txi_sign)
tx_ser.serialized_tx = w_txi
tx_req.serialized = tx_ser
elif coin.force_bip143 or tx.overwintered:
# STAGE_REQUEST_SEGWIT_INPUT
txi_sign = await helpers.request_tx_input(tx_req, i_sign)
input_check_wallet_path(txi_sign, wallet_path)
is_bip143 = (txi_sign.script_type == InputScriptType.SPENDADDRESS
or txi_sign.script_type
== InputScriptType.SPENDMULTISIG)
if not is_bip143 or txi_sign.amount > authorized_in:
raise SigningError(FailureType.ProcessError,
"Transaction has changed during signing")
authorized_in -= txi_sign.amount
key_sign = keychain.derive(txi_sign.address_n, coin.curve_name)
key_sign_pub = key_sign.public_key()
hash143_hash = hash143.preimage_hash(
coin,
tx,
txi_sign,
addresses.ecdsa_hash_pubkey(key_sign_pub, coin),
get_hash_type(coin),
)
# if multisig, check if signing with a key that is included in multisig
if txi_sign.multisig:
multisig.multisig_pubkey_index(txi_sign.multisig, key_sign_pub)
signature = ecdsa_sign(key_sign, hash143_hash)
tx_ser.signature_index = i_sign
tx_ser.signature = signature
# serialize input with correct signature
txi_sign.script_sig = input_derive_script(coin, txi_sign,
key_sign_pub, signature)
w_txi_sign = writers.empty_bytearray(5 + len(txi_sign.prev_hash) +
4 + len(txi_sign.script_sig) +
4)
if i_sign == 0: # serializing first input => prepend headers
writers.write_bytes(w_txi_sign, get_tx_header(coin, tx))
writers.write_tx_input(w_txi_sign, txi_sign)
tx_ser.serialized_tx = w_txi_sign
tx_req.serialized = tx_ser
elif coin.decred:
txi_sign = await helpers.request_tx_input(tx_req, i_sign)
input_check_wallet_path(txi_sign, wallet_path)
key_sign = keychain.derive(txi_sign.address_n, coin.curve_name)
key_sign_pub = key_sign.public_key()
if txi_sign.script_type == InputScriptType.SPENDMULTISIG:
prev_pkscript = scripts.output_script_multisig(
multisig.multisig_get_pubkeys(txi_sign.multisig),
txi_sign.multisig.m,
)
elif txi_sign.script_type == InputScriptType.SPENDADDRESS:
prev_pkscript = scripts.output_script_p2pkh(
addresses.ecdsa_hash_pubkey(key_sign_pub, coin))
else:
raise ValueError("Unknown input script type")
h_witness = utils.HashWriter(blake256())
writers.write_uint32(
h_witness,
tx.version | decred.DECRED_SERIALIZE_WITNESS_SIGNING)
writers.write_varint(h_witness, tx.inputs_count)
for ii in range(tx.inputs_count):
if ii == i_sign:
writers.write_varint(h_witness, len(prev_pkscript))
writers.write_bytes(h_witness, prev_pkscript)
else:
writers.write_varint(h_witness, 0)
witness_hash = writers.get_tx_hash(h_witness,
double=coin.sign_hash_double,
reverse=False)
h_sign = utils.HashWriter(blake256())
writers.write_uint32(h_sign, decred.DECRED_SIGHASHALL)
writers.write_bytes(h_sign, prefix_hash)
writers.write_bytes(h_sign, witness_hash)
sig_hash = writers.get_tx_hash(h_sign,
double=coin.sign_hash_double)
signature = ecdsa_sign(key_sign, sig_hash)
tx_ser.signature_index = i_sign
tx_ser.signature = signature
# serialize input with correct signature
txi_sign.script_sig = input_derive_script(coin, txi_sign,
key_sign_pub, signature)
w_txi_sign = writers.empty_bytearray(
8 + 4 +
len(hash143.get_last_output_bytes()) if i_sign == 0 else 0 +
16 + 4 + len(txi_sign.script_sig))
if i_sign == 0:
writers.write_bytes(w_txi_sign,
hash143.get_last_output_bytes())
writers.write_uint32(w_txi_sign, tx.lock_time)
writers.write_uint32(w_txi_sign, tx.expiry)
writers.write_varint(w_txi_sign, tx.inputs_count)
writers.write_tx_input_decred_witness(w_txi_sign, txi_sign)
tx_ser.serialized_tx = w_txi_sign
tx_req.serialized = tx_ser
else:
# hash of what we are signing with this input
h_sign = utils.HashWriter(sha256())
# same as h_first, checked before signing the digest
h_second = utils.HashWriter(sha256())
if tx.overwintered:
writers.write_uint32(
h_sign, tx.version
| zcash.OVERWINTERED) # nVersion | fOverwintered
writers.write_uint32(h_sign,
tx.version_group_id) # nVersionGroupId
else:
writers.write_uint32(h_sign, tx.version) # nVersion
if tx.timestamp:
writers.write_uint32(h_sign, tx.timestamp)
writers.write_varint(h_sign, tx.inputs_count)
for i in range(tx.inputs_count):
# STAGE_REQUEST_4_INPUT
txi = await helpers.request_tx_input(tx_req, i)
input_check_wallet_path(txi, wallet_path)
writers.write_tx_input_check(h_second, txi)
if i == i_sign:
txi_sign = txi
key_sign = keychain.derive(txi.address_n, coin.curve_name)
key_sign_pub = key_sign.public_key()
# for the signing process the script_sig is equal
# to the previous tx's scriptPubKey (P2PKH) or a redeem script (P2SH)
if txi_sign.script_type == InputScriptType.SPENDMULTISIG:
txi_sign.script_sig = scripts.output_script_multisig(
multisig.multisig_get_pubkeys(txi_sign.multisig),
txi_sign.multisig.m,
)
elif txi_sign.script_type == InputScriptType.SPENDADDRESS:
txi_sign.script_sig = scripts.output_script_p2pkh(
addresses.ecdsa_hash_pubkey(key_sign_pub, coin))
if coin.bip115:
txi_sign.script_sig += scripts.script_replay_protection_bip115(
txi_sign.prev_block_hash_bip115,
txi_sign.prev_block_height_bip115,
)
else:
raise SigningError(FailureType.ProcessError,
"Unknown transaction type")
else:
txi.script_sig = bytes()
writers.write_tx_input(h_sign, txi)
writers.write_varint(h_sign, tx.outputs_count)
for o in range(tx.outputs_count):
# STAGE_REQUEST_4_OUTPUT
txo = await helpers.request_tx_output(tx_req, o)
txo_bin.amount = txo.amount
txo_bin.script_pubkey = output_derive_script(
txo, coin, keychain)
writers.write_tx_output(h_second, txo_bin)
writers.write_tx_output(h_sign, txo_bin)
writers.write_uint32(h_sign, tx.lock_time)
if tx.overwintered:
writers.write_uint32(h_sign, tx.expiry) # expiryHeight
writers.write_varint(h_sign, 0) # nJoinSplit
writers.write_uint32(h_sign, get_hash_type(coin))
# check the control digests
if writers.get_tx_hash(h_first,
False) != writers.get_tx_hash(h_second):
raise SigningError(FailureType.ProcessError,
"Transaction has changed during signing")
# if multisig, check if signing with a key that is included in multisig
if txi_sign.multisig:
multisig.multisig_pubkey_index(txi_sign.multisig, key_sign_pub)
# compute the signature from the tx digest
signature = ecdsa_sign(
key_sign,
writers.get_tx_hash(h_sign, double=coin.sign_hash_double))
tx_ser.signature_index = i_sign
tx_ser.signature = signature
# serialize input with correct signature
txi_sign.script_sig = input_derive_script(coin, txi_sign,
key_sign_pub, signature)
w_txi_sign = writers.empty_bytearray(5 + len(txi_sign.prev_hash) +
4 + len(txi_sign.script_sig) +
4)
if i_sign == 0: # serializing first input => prepend headers
writers.write_bytes(w_txi_sign, get_tx_header(coin, tx))
writers.write_tx_input(w_txi_sign, txi_sign)
tx_ser.serialized_tx = w_txi_sign
tx_req.serialized = tx_ser
if coin.decred:
return await helpers.request_tx_finish(tx_req)
for o in range(tx.outputs_count):
progress.advance()
# STAGE_REQUEST_5_OUTPUT
txo = await helpers.request_tx_output(tx_req, o)
txo_bin.amount = txo.amount
txo_bin.script_pubkey = output_derive_script(txo, coin, keychain)
# serialize output
w_txo_bin = writers.empty_bytearray(5 + 8 + 5 +
len(txo_bin.script_pubkey) + 4)
if o == 0: # serializing first output => prepend outputs count
writers.write_varint(w_txo_bin, tx.outputs_count)
writers.write_tx_output(w_txo_bin, txo_bin)
tx_ser.signature_index = None
tx_ser.signature = None
tx_ser.serialized_tx = w_txo_bin
tx_req.serialized = tx_ser
any_segwit = True in segwit.values()
for i in range(tx.inputs_count):
progress.advance()
if segwit[i]:
# STAGE_REQUEST_SEGWIT_WITNESS
txi = await helpers.request_tx_input(tx_req, i)
input_check_wallet_path(txi, wallet_path)
if not input_is_segwit(txi) or txi.amount > authorized_in:
raise SigningError(FailureType.ProcessError,
"Transaction has changed during signing")
authorized_in -= txi.amount
key_sign = keychain.derive(txi.address_n, coin.curve_name)
key_sign_pub = key_sign.public_key()
hash143_hash = hash143.preimage_hash(
coin,
tx,
txi,
addresses.ecdsa_hash_pubkey(key_sign_pub, coin),
get_hash_type(coin),
)
signature = ecdsa_sign(key_sign, hash143_hash)
if txi.multisig:
# find out place of our signature based on the pubkey
signature_index = multisig.multisig_pubkey_index(
txi.multisig, key_sign_pub)
witness = scripts.witness_p2wsh(txi.multisig, signature,
signature_index,
get_hash_type(coin))
else:
witness = scripts.witness_p2wpkh(signature, key_sign_pub,
get_hash_type(coin))
tx_ser.serialized_tx = witness
tx_ser.signature_index = i
tx_ser.signature = signature
elif any_segwit:
tx_ser.serialized_tx = bytearray(
1) # empty witness for non-segwit inputs
tx_ser.signature_index = None
tx_ser.signature = None
tx_req.serialized = tx_ser
writers.write_uint32(tx_ser.serialized_tx, tx.lock_time)
if tx.overwintered:
if tx.version == 3:
writers.write_uint32(tx_ser.serialized_tx,
tx.expiry) # expiryHeight
writers.write_varint(tx_ser.serialized_tx, 0) # nJoinSplit
elif tx.version == 4:
writers.write_uint32(tx_ser.serialized_tx,
tx.expiry) # expiryHeight
writers.write_uint64(tx_ser.serialized_tx, 0) # valueBalance
writers.write_varint(tx_ser.serialized_tx, 0) # nShieldedSpend
writers.write_varint(tx_ser.serialized_tx, 0) # nShieldedOutput
writers.write_varint(tx_ser.serialized_tx, 0) # nJoinSplit
else:
raise SigningError(
FailureType.DataError,
"Unsupported version for overwintered transaction",
)
await helpers.request_tx_finish(tx_req)