def test_mutable_tx_creation_with_immutable_parts_specified(self):
tx = CMutableTransaction(
vin=[CTxIn(prevout=COutPoint(hash=b'a' * 32, n=0))],
vout=[CTxOut(nValue=1)],
witness=CTxWitness([CTxInWitness()]))
def check_mutable_parts(tx):
self.assertTrue(tx.vin[0].is_mutable())
self.assertTrue(tx.vin[0].prevout.is_mutable())
self.assertTrue(tx.vout[0].is_mutable())
self.assertTrue(tx.wit.is_mutable())
self.assertTrue(tx.wit.vtxinwit[0].is_mutable())
check_mutable_parts(tx)
# Test that if we deserialize with CMutableTransaction,
# all the parts are mutable
tx = CMutableTransaction.deserialize(tx.serialize())
check_mutable_parts(tx)
# Test some parts separately, because when created via
# CMutableTransaction instantiation, they are created with from_*
# methods, and not directly
txin = CMutableTxIn(prevout=COutPoint(hash=b'a' * 32, n=0))
self.assertTrue(txin.prevout.is_mutable())
wit = CMutableTxWitness((CTxInWitness(), ))
self.assertTrue(wit.vtxinwit[0].is_mutable())
def create_test_txs(self, scriptSig, scriptPubKey, witness, nValue):
txCredit = CTransaction([CTxIn(COutPoint(), CScript([OP_0, OP_0]), nSequence=0xFFFFFFFF)],
[CTxOut(nValue, scriptPubKey)],
witness=CTxWitness(),
nLockTime=0, nVersion=1)
txSpend = CTransaction([CTxIn(COutPoint(txCredit.GetTxid(), 0), scriptSig, nSequence=0xFFFFFFFF)],
[CTxOut(nValue, CScript())],
nLockTime=0, nVersion=1,
witness=CTxWitness([CTxInWitness(witness)]))
return (txCredit, txSpend)
def test_repr(self):
def T(outpoint, expected):
actual = repr(outpoint)
self.assertEqual(actual, expected)
T(COutPoint(), 'CBitcoinOutPoint()')
T(
COutPoint(
lx('4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b'
), 0),
"CBitcoinOutPoint(lx('4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b'), 0)"
)
def listunspent(self, minconf=0, maxconf=9999999, addrs=None):
"""Return unspent transaction outputs in wallet
Outputs will have between minconf and maxconf (inclusive)
confirmations, optionally filtered to only include txouts paid to
addresses in addrs.
"""
r = None
if addrs is None:
r = self._call('listunspent', minconf, maxconf)
else:
addrs = [str(addr) for addr in addrs]
r = self._call('listunspent', minconf, maxconf, addrs)
r2 = []
for unspent in r:
unspent['outpoint'] = COutPoint(lx(unspent['txid']),
unspent['vout'])
del unspent['txid']
del unspent['vout']
# address isn't always available as Bitcoin Core allows scripts w/o
# an address type to be imported into the wallet, e.g. non-p2sh
# segwit
try:
unspent['address'] = CBitcoinAddress(unspent['address'])
except KeyError:
pass
unspent['scriptPubKey'] = CScript(
unhexlify(unspent['scriptPubKey']))
unspent['amount'] = int(unspent['amount'] * COIN)
r2.append(unspent)
return r2
def generate_transaction(amount, txin_txid, txin_vout, txout_addr,
redeem_list):
txin = CMutableTxIn(COutPoint(txin_txid, txin_vout))
txout = CMutableTxOut(amount * COIN, txout_addr.addr.to_scriptPubKey())
witness_script = CScriptWitness(tuple(redeem_list))
witness = CTxWitness(tuple([CTxInWitness(witness_script)]))
tx = CMutableTransaction(vin=[txin], vout=[txout], witness=witness)
return tx
def test_clone(self):
outpoint = COutPoint(
lx('4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b'
), 0)
txin = CMutableTxIn(prevout=outpoint,
scriptSig=CScript(b'\x03abc'),
nSequence=0xffffffff)
self.assertEqual(txin.serialize(), txin.clone().serialize())
def test_str(self):
def T(outpoint, expected):
actual = str(outpoint)
self.assertEqual(actual, expected)
T(
COutPoint(),
'0000000000000000000000000000000000000000000000000000000000000000:4294967295'
)
T(
COutPoint(
lx('4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b'
), 0),
'4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b:0'
)
T(
COutPoint(
lx('4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b'
), 10),
'4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b:10'
)
def create_btc_spend_tx(dst_addr,
txid,
vout_n,
btc_contract,
spend_key=None,
branch_condition=True):
# In real application, the fees should not be static, of course
out_amount = (coins_to_satoshi(pre_agreed_amount) -
coins_to_satoshi(fixed_fee_amount))
tx = CMutableTransaction(
vin=[CTxIn(prevout=COutPoint(hash=lx(txid), n=vout_n))],
vout=[
CTxOut(nValue=out_amount, scriptPubKey=dst_addr.to_scriptPubKey())
])
if branch_condition is True:
cond = b'\x01'
else:
tx.vin[0].nSequence = bitcoin_contract_timeout
cond = b''
in_amount = coins_to_satoshi(pre_agreed_amount)
# We used P2WSHCoinAddress to create the address that we sent bitcoin to,
# so we know that we need to use SIGVERSION_WITNESS_V0
sighash = btc_contract.sighash(tx,
0,
SIGHASH_ALL,
amount=in_amount,
sigversion=SIGVERSION_WITNESS_V0)
spend_sig = spend_key.sign(sighash) + bytes([SIGHASH_ALL])
# This is script witness, not script. The condition for OP_IF
# in our script is directly encoded as data in the witness.
# We cannot use OP_TRUE/OP_FALSE here. We use DATA guard is to ensure that.
witness = CScriptWitness([spend_sig, DATA(cond), btc_contract])
# empty scriptSig, because segwit
tx.vin[0].scriptSig = CBitcoinScript([])
# all data to check the spend conditions is in the witness
tx.wit.vtxinwit[0] = CTxInWitness(witness)
# Cannot use VerifyScript for now,
# because it does not support CHECKSEQUENCEVERIFY yet
#
# from_addr = P2WSHBitcoinAddress.from_redeemScript(btc_contract)
# VerifyScript(tx.vin[0].scriptSig, from_addr.to_scriptPubKey(),
# tx, 0, amount=in_amount)
return tx
def raw_multisig(self):
source = self.next_address()
self.fund_address(source, 0.1)
# construct transaction manually
tx_ins = [CMutableTxIn(COutPoint(source.txid, source.vout))]
keys = [self.next_address().key for _ in range(3)]
redeem_script = CScript([OP_2, keys[0].pub, keys[1].pub, keys[2].pub, OP_3, OP_CHECKMULTISIG])
tx_outs = [
CMutableTxOut(Coin(0.1 - self.fee).satoshi(), redeem_script)]
tx = CMutableTransaction(tx_ins, tx_outs)
# sign and submit
key = source.key
script = source.address.to_scriptPubKey()
sig = self._sign(script, tx, 0, Coin(source.value).satoshi(), key)
tx_ins[0].scriptSig = CScript([sig, key.pub])
txid = self._send_transaction(tx, [])
self.log_value("raw-multisig-tx", txid)
# Redeem Transaction
tx_ins = [CMutableTxIn(COutPoint(lx(txid), 0))]
destination = self.next_address()
tx_outs = [CMutableTxOut(Coin(0.1 - 2 * self.fee).satoshi(), destination.address.to_scriptPubKey())]
tx = CMutableTransaction(tx_ins, tx_outs)
# Sign with 2 out of three keys
sig1 = self._sign(redeem_script, tx, 0, Coin(0.1 - self.fee).satoshi(), keys[0])
sig3 = self._sign(redeem_script, tx, 0, Coin(0.1 - self.fee).satoshi(), keys[2])
tx_ins[0].scriptSig = CScript([OP_0, sig1, sig3])
txid = self._send_transaction(tx, [])
self.log_value("raw-multisig-redeem-tx", txid)
self.generate_block()
def test_sighash(self) -> None:
spent_amount = 1100
pub = CKey.from_secret_bytes(os.urandom(32)).pub
spk_legacy = P2PKHCoinAddress.from_pubkey(pub).to_scriptPubKey()
spk_segwit = P2WPKHCoinAddress.from_pubkey(pub).to_scriptPubKey()
tx = CTransaction([
CTxIn(
COutPoint(b'\x00' * 32, 0), CScript([]), nSequence=0xFFFFFFFF)
], [CTxOut(1000, spk_legacy)],
nLockTime=0,
nVersion=1)
# no exceptions should be raised with these two calls
spk_legacy.sighash(tx,
0,
SIGHASH_ALL,
amount=spent_amount,
sigversion=SIGVERSION_WITNESS_V0)
spk_segwit.sighash(tx,
0,
SIGHASH_ALL,
amount=spent_amount,
sigversion=SIGVERSION_WITNESS_V0)
with self.assertRaises(ValueError):
# unknown sigversion
spk_segwit.sighash(tx,
0,
SIGHASH_ALL,
amount=spent_amount,
sigversion=SIGVERSION_WITNESS_V0 +
1) # type: ignore
assert spk_segwit.is_witness_scriptpubkey()
with self.assertRaises(ValueError):
# incorect sigversion for segwit
spk_segwit.sighash(tx,
0,
SIGHASH_ALL,
amount=spent_amount,
sigversion=SIGVERSION_BASE)
with self.assertRaises(ValueError):
# inIdx > len(tx.vin) - non-raw sighash function should raise
# ValueError (raw_sighash can return HASH_ONE)
spk_legacy.sighash(tx,
10,
SIGHASH_ALL,
amount=spent_amount,
sigversion=SIGVERSION_BASE)
def op_return(self):
source = self.next_address("p2pkh")
self.fund_address(source, 2 * self.fee)
tx_ins = [CMutableTxIn(COutPoint(source.txid, source.vout))]
tx_outs = [CMutableTxOut(Coin(self.fee).satoshi(), CScript([OP_RETURN, x("4c6f726420566f6c64656d6f7274")]))]
tx = CMutableTransaction(tx_ins, tx_outs)
key = source.key
script = source.address.to_scriptPubKey()
sig = self._sign(script, tx, 0, Coin(source.value).satoshi(), key)
tx_ins[0].scriptSig = CScript([sig, key.pub])
txid = self._send_transaction(tx, [])
self.log_value("op-return-tx", txid)
def create_custom_block(self, reward):
txid, _ = self.fund_address(self.next_address(), 10)
tx2 = self.proxy.getrawtransaction(lx(txid))
coinbase = CMutableTransaction()
coinbase.vin.append(CMutableTxIn(COutPoint(), CScript([self.proxy.getblockcount() + 1])))
coinbase.vout.append(CMutableTxOut(reward * COIN, self.next_address().address.to_scriptPubKey()))
prev_block_hash = self.proxy.getblockhash(self.proxy.getblockcount())
ts = self._next_timestamp()
self.proxy.call("setmocktime", ts)
for nonce in range(1000):
block = CBlock(nBits=0x207fffff, vtx=[coinbase, tx2], hashPrevBlock=prev_block_hash, nTime=ts, nNonce=nonce)
result = self.proxy.submitblock(block)
if not result:
self.log.debug("Chosen nonce: {}".format(nonce))
break
def load_test_vectors(name):
with open(os.path.dirname(__file__) + '/data/' + name, 'r') as fd:
for test_case in json.load(fd):
# Comments designated by single length strings
if len(test_case) == 1:
continue
assert len(test_case) == 3
prevouts = {}
for json_prevout in test_case[0]:
assert len(json_prevout) == 3
n = json_prevout[1]
if n == -1:
n = 0xffffffff
prevout = COutPoint(lx(json_prevout[0]), n)
prevouts[prevout] = parse_script(json_prevout[2])
tx_data = x(test_case[1])
tx = CTransaction.deserialize(tx_data)
enforceP2SH = test_case[2]
yield (prevouts, tx, tx_data, enforceP2SH)
def test_immutable_tx_creation_with_mutable_parts_specified(self) -> None:
tx = CElementsTransaction(
vin=[CMutableTxIn(prevout=COutPoint(hash=b'a' * 32, n=0))],
vout=[CMutableTxOut()],
witness=CMutableTxWitness(
[CMutableTxInWitness(CScriptWitness([CScript([0])]))],
[CMutableTxOutWitness()]))
self.assertIsInstance(tx, CElementsTransaction)
def check_immutable_parts(tx: CElementsTransaction) -> None:
self.assertTrue(not tx.vin[0].is_mutable())
self.assertTrue(not tx.vin[0].prevout.is_mutable())
self.assertTrue(not tx.vout[0].is_mutable())
self.assertTrue(not tx.wit.is_mutable())
self.assertTrue(not tx.wit.vtxinwit[0].is_mutable())
self.assertTrue(not tx.wit.vtxoutwit[0].is_mutable())
check_immutable_parts(tx)
# Test that if we deserialize with CTransaction,
# all the parts are immutable
tx = CElementsTransaction.deserialize(tx.serialize())
check_immutable_parts(tx)
# Test some parts separately, because when created via
# CMutableTransaction instantiation, they are created with from_*
# methods, and not directly
txin = CTxIn(prevout=CMutableOutPoint(hash=b'a' * 32, n=0))
self.assertTrue(not txin.prevout.is_mutable())
wit = CElementsTxWitness((CElementsMutableTxInWitness(), ),
(CElementsMutableTxOutWitness(), ))
self.assertTrue(not wit.vtxinwit[0].is_mutable())
self.assertTrue(not wit.vtxoutwit[0].is_mutable())
# Create the (in)famous correct brainwallet secret key.
h = hashlib.sha256(b'correct horse battery staple').digest()
seckey = CBitcoinKey.from_secret_bytes(h)
# Same as the txid:vout the createrawtransaction RPC call requires
#
# lx() takes *little-endian* hex and converts it to bytes; in Bitcoin
# transaction hashes are shown little-endian rather than the usual big-endian.
# There's also a corresponding x() convenience function that takes big-endian
# hex and converts it to bytes.
txid = lx('7e195aa3de827814f172c362fcf838d92ba10e3f9fdd9c3ecaf79522b311b22d')
vout = 0
# Create the txin structure, which includes the outpoint. The scriptSig
# defaults to being empty.
txin = CMutableTxIn(COutPoint(txid, vout))
# We also need the scriptPubKey of the output we're spending because
# SignatureHash() replaces the transaction scriptSig's with it.
#
# Here we'll create that scriptPubKey from scratch using the pubkey that
# corresponds to the secret key we generated above.
txin_scriptPubKey = \
P2PKHBitcoinAddress.from_pubkey(seckey.pub).to_scriptPubKey()
# Create the txout. This time we create the scriptPubKey from a Bitcoin
# address.
txout = CMutableTxOut(
0.001 * COIN,
CBitcoinAddress('1C7zdTfnkzmr13HfA2vNm5SJYRK6nEKyq8').to_scriptPubKey())
def test_immutable(self):
"""COutPoint shall not be mutable"""
outpoint = COutPoint()
with self.assertRaises(AttributeError):
outpoint.n = 1
def create_elt_spend_tx(dst_addr,
txid,
vout_n,
elt_contract,
die,
spend_key=None,
contract_key=None,
blinding_key=None,
blinding_factor=None,
asset_blinding_factor=None,
branch_condition=True):
fee_satoshi = coins_to_satoshi(fixed_fee_amount)
out_amount = coins_to_satoshi(pre_agreed_amount) - fee_satoshi
# Single blinded output is not allowed, so we add
# dummy OP_RETURN output, and we need dummy pubkey for it
dummy_key = CKey.from_secret_bytes(os.urandom(32))
tx = CMutableTransaction(
vin=[CTxIn(prevout=COutPoint(hash=lx(txid), n=vout_n))],
vout=[
CTxOut(nValue=CConfidentialValue(out_amount),
nAsset=CConfidentialAsset(bitcoin_asset),
scriptPubKey=dst_addr.to_scriptPubKey(),
nNonce=CConfidentialNonce(dst_addr.blinding_pubkey)),
CTxOut(nValue=CConfidentialValue(0),
nAsset=CConfidentialAsset(bitcoin_asset),
nNonce=CConfidentialNonce(dummy_key.pub),
scriptPubKey=CElementsScript([OP_RETURN])),
CTxOut(nValue=CConfidentialValue(fee_satoshi),
nAsset=CConfidentialAsset(bitcoin_asset))
])
output_pubkeys = [dst_addr.blinding_pubkey, dummy_key.pub]
in_amount = coins_to_satoshi(pre_agreed_amount)
input_descriptors = [
BlindingInputDescriptor(asset=bitcoin_asset,
amount=in_amount,
blinding_factor=blinding_factor,
asset_blinding_factor=asset_blinding_factor)
]
blind_result = tx.blind(input_descriptors=input_descriptors,
output_pubkeys=output_pubkeys)
# The blinding must succeed!
if blind_result.error:
die('blind failed: {}'.format(blind_result.error))
if branch_condition is False:
# Must set nSequence before we calculate signature hash,
# because it is included in it
tx.vin[0].nSequence = elements_contract_timeout
# We used P2SHCoinAddress to create the address that
# we sent Elements-BTC to, so we know that we need
# to use SIGVERSION_BASE
sighash = elt_contract.sighash(tx,
0,
SIGHASH_ALL,
amount=CConfidentialValue(in_amount),
sigversion=SIGVERSION_BASE)
spend_sig = spend_key.sign(sighash) + bytes([SIGHASH_ALL])
if branch_condition is True:
prepare_elt_spend_reveal_branch(tx, elt_contract, spend_sig,
contract_key, blinding_key)
else:
tx.vin[0].scriptSig = CElementsScript(
[spend_sig, OP_FALSE, elt_contract])
return tx
def _create_transaction(self, sources: List[Address],
recipients: List[Address], values, n_locktime,
n_sequence):
# save cospends
self.cospends.union_all([str(x.address) for x in sources])
if not values:
values = [recipient.value for recipient in recipients]
tx_ins = [
CMutableTxIn(COutPoint(source.txid, source.vout),
nSequence=n_sequence) for source in sources
]
tx_outs = []
cnt = 0
for recipient, value in zip(recipients, values):
if value == 0:
self.log.warning("Creating output with 0 BTC")
recipient.vout = cnt
tx_outs.append(
CMutableTxOut(
Coin(value).satoshi(),
recipient.address.to_scriptPubKey()))
cnt += 1
tx = CMutableTransaction(tx_ins, tx_outs, nLockTime=n_locktime)
in_idx = 0
witnesses = []
for txin, source in zip(tx_ins, sources):
key = source.key
if source.type == 'p2pkh':
script = source.address.to_redeemScript()
elif source.type == 'p2sh':
script = CScript([key.pub, OP_CHECKSIG])
elif source.type == 'p2wpkh':
script = source.address.to_redeemScript()
elif source.type == 'p2wsh':
script = source.witness_program
else:
raise UnsupportedAddressTypeError()
# Create signature
amount = Coin(source.value).satoshi()
sig = self._sign(script, tx, in_idx, amount, key, source.type)
# Add signature to input or witness
if source.type == 'p2pkh':
txin.scriptSig = CScript([sig, key.pub])
witnesses.append(CTxInWitness())
elif source.type == 'p2sh':
txin.scriptSig = CScript([sig, script])
witnesses.append(CTxInWitness())
elif source.type == 'p2wpkh':
txin.scriptSig = CScript()
witnesses.append(CTxInWitness(CScriptWitness([sig, key.pub])))
elif source.type == 'p2wsh':
txin.scriptSig = CScript()
witnesses.append(CTxInWitness(CScriptWitness([sig, script])))
in_idx += 1
tx.wit = CTxWitness(witnesses)
return tx
def test_is_null(self):
self.assertTrue(COutPoint().is_null())
self.assertTrue(COutPoint(hash=b'\x00' * 32, n=0xffffffff).is_null())
self.assertFalse(COutPoint(hash=b'\x00' * 31 + b'\x01').is_null())
self.assertFalse(COutPoint(n=1).is_null())
def claim_funds_back(say, utxos, die, rpc):
"""Try to claim our funds by sending our UTXO to our own addresses"""
# The transaction-building code here does not introduce anything new
# compared to the code in participant functions, so it will not be
# commented too much.
input_descriptors = []
# It is better to prepare the claw-back transaction beforehand, to avoid
# the possibility of unexpected problems arising at the critical time when
# we need to send claw-back tx ASAP, but that would clutter the earlier
# part of the example with details that are not very relevant there.
tx = CMutableTransaction()
for utxo in utxos:
tx.vin.append(
CTxIn(prevout=COutPoint(hash=lx(utxo['txid']), n=utxo['vout'])))
input_descriptors.append(
BlindingInputDescriptor(
asset=CAsset(lx(utxo['asset'])),
amount=coins_to_satoshi(utxo['amount']),
blinding_factor=Uint256(lx(utxo['amountblinder'])),
asset_blinding_factor=Uint256(lx(utxo['assetblinder']))))
asset_amounts = {}
# If some assets are the same, we want them to be sent to one address
for idesc in input_descriptors:
if idesc.asset == fee_asset:
amount = idesc.amount - FIXED_FEE_SATOSHI
assert amount >= FIXED_FEE_SATOSHI # enforced at find_utxo_for_fee
else:
amount = idesc.amount
asset_amounts[idesc.asset] = amount
output_pubkeys = []
for asset, amount in asset_amounts.items():
dst_addr, _ = get_dst_addr(None, rpc)
tx.vout.append(
CTxOut(nValue=CConfidentialValue(amount),
nAsset=CConfidentialAsset(asset),
scriptPubKey=dst_addr.to_scriptPubKey()))
output_pubkeys.append(dst_addr.blinding_pubkey)
# Add the explicit fee output
tx.vout.append(
CTxOut(nValue=CConfidentialValue(FIXED_FEE_SATOSHI),
nAsset=CConfidentialAsset(fee_asset)))
# Add dummy pubkey for non-blinded fee output
output_pubkeys.append(CPubKey())
# We used immutable objects for transaction components like CTxIn,
# just for our convenience. Convert them all to mutable.
tx = tx.to_immutable().to_mutable()
# And blind the combined transaction
blind_result = tx.blind(input_descriptors=input_descriptors,
output_pubkeys=output_pubkeys)
assert (not blind_result.error
and blind_result.num_successfully_blinded == len(utxos))
for n, utxo in enumerate(utxos):
sign_input(tx, n, utxo)
# It is possible that Bob has actually sent the swap transaction.
# We will get an error if our node has received this transaction.
# In real application, we might handle this case, too, but
# here we will just ignore it.
txid = rpc.sendrawtransaction(b2x(tx.serialize()))
rpc.generatetoaddress(1, rpc.getnewaddress())
wait_confirm(say, txid, die, rpc)
def alice(say, recv, send, die, rpc):
"""A function that implements the logic
of the first participant of an asset atomic swap"""
# Issue two asset that we are going to swap to Bob's 1 asset
asset1_str, asset1_utxo = issue_asset(say, 1.0, rpc)
asset2_str, asset2_utxo = issue_asset(say, 1.0, rpc)
# We will need to pay a fee in an asset suitable for this
fee_utxo = find_utxo_for_fee(say, die, rpc)
say('Getting change address for fee asset')
# We don't care for blinding key of change - the node will
# have it, anyway, and we don't need to unblind the change.
fee_change_addr, _ = get_dst_addr(say, rpc)
say('Will use utxo {}:{} (amount: {}) for fee, change will go to {}'.
format(fee_utxo['txid'], fee_utxo['vout'], fee_utxo['amount'],
fee_change_addr))
say('Setting up communication with Bob')
# Tell Bob that we are ready to communicate
send('ready')
# To avoid mempool synchronization problems,
# in our example Alice is the one in charge of generating test blocks.
# Bob gives alice txid of his transaction that he wants to be confirmed.
bob_txid = recv('wait-txid-confirm')
# Make sure asset issuance transactions are confirmed
rpc.generatetoaddress(1, rpc.getnewaddress())
wait_confirm(say, asset1_utxo['txid'], die, rpc)
wait_confirm(say, asset2_utxo['txid'], die, rpc)
wait_confirm(say, bob_txid, die, rpc)
# Make sure Bob is alive and ready to communicate, and send
# him an offer for two assets
say('Sending offer to Bob')
my_offers = [
AtomicSwapOffer(asset=asset1_str,
amount=coins_to_satoshi(asset1_utxo['amount'])),
AtomicSwapOffer(asset=asset2_str,
amount=coins_to_satoshi(asset2_utxo['amount']))
]
send('offer', my_offers)
bob_offer = recv('offer')
print_asset_balances(say, my_offers + [bob_offer], rpc)
say('Bob responded with his offer: {}'.format(bob_offer))
# We unconditionally accept Bob's offer - his asset is
# equally worthless as ours :-)
# Generate an address for Bob to send his asset to.
dst_addr, blinding_key = get_dst_addr(say, rpc)
say('Sending my address and assetcommitments for my UTXOs to Bob')
# Send Bob our address, and the assetcommitments of our UTXOs
# (but not any other information about our UTXO),
# so he can construct and blind a partial transaction that
# will spend his own UTXO, to send his asset to our address.
assetcommitments = [
asset1_utxo['assetcommitment'], asset2_utxo['assetcommitment'],
fee_utxo['assetcommitment']
]
send('addr_and_assetcommitments', (str(dst_addr), assetcommitments))
partial_tx_bytes = recv('partial_blinded_tx')
say('Got partial blinded tx of size {} bytes from Bob'.format(
len(partial_tx_bytes)))
partial_tx = CTransaction.deserialize(partial_tx_bytes)
if len(partial_tx.vout) != 1:
die('unexpected number of outputs in tx from Bob: expected 1, got {}'.
format(len(partial_tx.vout)))
result = partial_tx.vout[0].unblind_confidential_pair(
blinding_key, partial_tx.wit.vtxoutwit[0].rangeproof)
if result.error:
die('cannot unblind output that should have been directed to us: {}'.
format(result.error))
if result.asset.to_hex() != bob_offer.asset:
die("asset in partial transaction from Bob {} is not the same "
"as asset in Bob's initial offer ({})".format(
result.asset.to_hex(), bob_offer.asset))
if result.amount != bob_offer.amount:
die("amount in partial transaction from Bob {} is not the same "
"as amount in Bob's initial offer ({})".format(
result.amount, bob_offer.amount))
say("Asset and amount in partial transaction matches Bob's offer")
bob_addr_list, bob_assetcommitment = recv('addr_list_and_assetcommitment')
if len(bob_addr_list) != len(my_offers):
die('unexpected address list lenth from Bob. expected {}, got {}'.
format(len(my_offers), len(bob_addr_list)))
say("Bob's addresses to receive my assets: {}".format(bob_addr_list))
# Convert Bob's addresses to address objects.
# If Bob passes invalid address, we die with with exception.
bob_addr_list = [CCoinAddress(a) for a in bob_addr_list]
# Add our own inputs and outputs to Bob's partial tx
# Create new mutable transaction from partial_tx
tx = partial_tx.to_mutable()
# We have assetcommitment for the first input,
# other data is not needed for it.
# initialize first elements of the arrays with empty/negative data.
input_descriptors = [
BlindingInputDescriptor(asset=CAsset(),
amount=-1,
blinding_factor=Uint256(),
asset_blinding_factor=Uint256())
]
# First output is already blinded, fill the slot with empty data
output_pubkeys = [CPubKey()]
# But assetcommitments array should start with Bob's asset commitment
assetcommitments = [x(bob_assetcommitment)]
# We will add our inputs for asset1 and asset2, and also an input
# that will be used to pay the fee.
# Note that the order is important: Bob blinded his transaction
# with assetcommitments in the order we send them to him,
# and we should add our inputs in the same order.
utxos_to_add = (asset1_utxo, asset2_utxo, fee_utxo)
# Add inputs for asset1 and asset2 and fee_asset and prepare input data
# for blinding
for utxo in utxos_to_add:
# When we create CMutableTransaction and pass CTxIn,
# it will be converted to CMutableTxIn. But if we append
# to tx.vin or tx.vout, we need to use mutable versions
# of the txin/txout classes, or else blinding or signing
# will fail with error, unable to modify the instances.
# COutPoint is not modified, though, so we can leave it
# immutable.
tx.vin.append(
CMutableTxIn(
prevout=COutPoint(hash=lx(utxo['txid']), n=utxo['vout'])))
input_descriptors.append(
BlindingInputDescriptor(
asset=CAsset(lx(utxo['asset'])),
amount=coins_to_satoshi(utxo['amount']),
blinding_factor=Uint256(lx(utxo['amountblinder'])),
asset_blinding_factor=Uint256(lx(utxo['assetblinder']))))
# If we are supplying asset blinders and assetblinders for
# particular input, assetcommitment data for that input do
# not need to be correct. But if we are supplying assetcommitments
# at all (auxiliary_generators argument to tx.blind()),
# then all the elements of that array must have correct
# type (bytes) and length (33). This is a requirement of the original
# Elements Core API, and python-elementstx requires this, too.
assetcommitments.append(b'\x00' * 33)
# Add outputs to give Bob all our assets, and fill output pubkeys
# for blinding the outputs to Bob's addresses
for n, offer in enumerate(my_offers):
tx.vout.append(
CMutableTxOut(nValue=CConfidentialValue(offer.amount),
nAsset=CConfidentialAsset(CAsset(lx(offer.asset))),
scriptPubKey=bob_addr_list[n].to_scriptPubKey()))
output_pubkeys.append(bob_addr_list[n].blinding_pubkey)
# Add change output for fee asset
fee_change_amount = (coins_to_satoshi(fee_utxo['amount']) -
FIXED_FEE_SATOSHI)
tx.vout.append(
CMutableTxOut(nValue=CConfidentialValue(fee_change_amount),
nAsset=CConfidentialAsset(fee_asset),
scriptPubKey=fee_change_addr.to_scriptPubKey()))
output_pubkeys.append(fee_change_addr.blinding_pubkey)
# Add fee output.
# Note that while we use CConfidentialAsset and CConfidentialValue
# to specify value and asset, they are not in fact confidential here
# - they are explicit, because we pass explicit values at creation.
# You can check if they are explicit or confidential
# with nValue.is_explicit(). If they are explicit, you can access
# the unblinded values with nValue.to_amount() and nAsset.to_asset()
tx.vout.append(
CMutableTxOut(nValue=CConfidentialValue(FIXED_FEE_SATOSHI),
nAsset=CConfidentialAsset(fee_asset)))
# Add dummy pubkey for non-blinded fee output
output_pubkeys.append(CPubKey())
# Our transaction lacks txin witness instances for the added inputs,
# and txout witness instances for added outputs.
# If transaction already have witness data attached, transaction
# serialization code will require in/out witness array length
# to be equal to vin/vout array length
# Therefore we need to add dummy txin and txout witnesses for each
# input and output that we added to transaction
# we added one input and one output per asset, and an additional
# input/change-output for fee asset.
for _ in utxos_to_add:
tx.wit.vtxinwit.append(CMutableTxInWitness())
tx.wit.vtxoutwit.append(CMutableTxOutWitness())
# And one extra dummy txout witness for fee output
tx.wit.vtxoutwit.append(CMutableTxOutWitness())
# And blind the combined transaction
blind_result = tx.blind(input_descriptors=input_descriptors,
output_pubkeys=output_pubkeys,
auxiliary_generators=assetcommitments)
# The blinding must succeed!
if blind_result.error:
die('blind failed: {}'.format(blind_result.error))
# And must blind exactly three outputs (two to Bob, one fee asset change)
if blind_result.num_successfully_blinded != 3:
die('blinded {} outputs, expected to be 3'.format(
blind_result.num_successfully_blinded))
say('Successfully blinded the combined transaction, will now sign')
# Sign two new asset inputs, and fee asset input
for n, utxo in enumerate(utxos_to_add):
# We specify input_index as 1+n because we skip first (Bob's) input
sign_input(tx, 1 + n, utxo)
say('Signed my inputs, sending partially-signed transaction to Bob')
send('partially_signed_tx', tx.serialize())
# Note that at this point both participants can still opt out of the swap:
# Alice by double-spending her inputs to the transaction,
# and Bob by not signing or not broadcasting the transaction.
# Bob still have tiny advantage, because
# he can pretend to have 'difficulties' in broadcasting and try to exploit
# Alice's patience. If Alice does not reclaim her funds in the case Bob's
# behaviour deviates from expected, then Bob will have free option to
# exectute the swap at the time convenient to him.
# Get the swap transaction from Bob.
# Bob is expected to broadcast this transaction, and could just send txid
# here, but then there would be a period of uncertainty: if Alice do not
# see the txid at her own node, she does not know if this is because Bob
# did not actually broadcast, and is just taking his time watching asset
# prices, or the transaction just takes long time to propagate. If the
# protocol requires Bob to send the transaction, the timeout required for
# Alice to wait can be defined much more certainly.
try:
signed_tx_raw = recv('final-signed-tx', timeout=ALICE_PATIENCE_LIMIT)
signed_tx = CTransaction.deserialize(x(signed_tx_raw))
# Check that this transaction spends the same inputs as the transacton
# previously agreed upon
for n, vin in enumerate(signed_tx.vin):
if vin.prevout != tx.vin[n].prevout:
die('Inputs of transaction received from Bob do not match '
'the agreed-upon transaction')
# Send the transaction from our side
txid = rpc.sendrawtransaction(b2x(signed_tx.serialize()))
except Exception as e:
# If there is any problem, including communication timeout or invalid
# communication, or invalid transaction encoding, then Alice will try
# to claim her funds back, so Bob won't have an option to execute the
# swap at the time convenient to him. He should execute it immediately.
say('Unexpected problem on receiving final signed transaction '
'from Bob: {}'.format(e))
say('This is suspicious. I will try to reclaim my funds now')
claim_funds_back(say, utxos_to_add, die, rpc)
say("Claimed my funds back. Screw Bob!")
sys.exit(0)
# Make sure the final transaction is confirmed
rpc.generatetoaddress(1, rpc.getnewaddress())
wait_confirm(say, txid, die, rpc)
# Check that everything went smoothly
balance = coins_to_satoshi(rpc.getbalance("*", 1, False, bob_offer.asset))
if balance != bob_offer.amount:
die('something went wrong, balance of Bob\'s asset after swap '
'should be {} satoshi, but it is {} satoshi'.format(
balance, bob_offer.amount))
print_asset_balances(say, my_offers + [bob_offer], rpc)
# Wait for alice to politely end the conversation
send('thanks-goodbye')
say('Asset atomic swap completed successfully')
def bob(say, recv, send, die, rpc):
"""A function that implements the logic
of the second participant of an asset atomic swap"""
# Issue an asset that we are going to swap
asset_str, asset_utxo = issue_asset(say, 1.0, rpc)
asset_amount_satoshi = coins_to_satoshi(asset_utxo['amount'])
say('Setting up communication with Alice')
# Wait for Alice to start communication
recv('ready')
# To avoid mempool synchronization problems in two-node regtest setup,
# in our example Alice is the one in charge of generating test blocks.
# Send txid of asset issuance to alice so she can ensure it is confirmed.
send('wait-txid-confirm', asset_utxo['txid'])
say('Waiting for Alice to send us an offer array')
alice_offers = recv('offer')
# We unconditionally accept Alice's offer - her assets are
# equally worthless as our asset :-)
say("Alice's offers are {}, sending my offer".format(alice_offers))
my_offer = AtomicSwapOffer(amount=asset_amount_satoshi, asset=asset_str)
send('offer', my_offer)
say('Waiting for Alice\'s address and assetcommitments')
alice_addr_str, alice_assetcommitments = recv('addr_and_assetcommitments')
print_asset_balances(say, alice_offers + [my_offer], rpc)
# Convert Alice's address to address object.
# If Alice passes invalid address, we die with we die with exception.
alice_addr = CCoinAddress(alice_addr_str)
say('Alice\'s address: {}'.format(alice_addr))
say('Alice\'s assetcommitments: {}'.format(alice_assetcommitments))
# Create asset commitments array. First goes our own asset commitment,
# because our UTXO will be first.
assetcommitments = [x(asset_utxo['assetcommitment'])]
for ac in alice_assetcommitments:
# If Alice sends non-hex data, we will die while converting.
assetcommitments.append(x(ac))
# Let's create our part of the transaction. We need to create
# mutable transaction, because blind() method only works for mutable.
partial_tx = CMutableTransaction(
vin=[
CTxIn(prevout=COutPoint(hash=lx(asset_utxo['txid']),
n=asset_utxo['vout']))
],
vout=[
CTxOut(nValue=CConfidentialValue(asset_amount_satoshi),
nAsset=CConfidentialAsset(CAsset(lx(asset_str))),
scriptPubKey=alice_addr.to_scriptPubKey())
])
# Blind our part of transaction, specifying assetcommitments
# (Incliding those received from Alice) as auxiliary_generators.
# Note that we could get the blinding factors if we retrieve
# the transaction that we spend from, deserialize it, and unblind
# the output that we are going to spend.
# We could do everything here (besides issuing the asset and sending
# the transactions) without using Elements RPC, if we get our data
# from files or database, etc. But to simplify our demonstration,
# we will use the values we got from RPC.
# See 'spend-to-confidential-address.py' example for the code
# that does the unblinding itself, and uses the unblinded values
# to create a spending transaction.
blind_result = partial_tx.blind(
input_descriptors=[
BlindingInputDescriptor(
asset=CAsset(lx(asset_utxo['asset'])),
amount=asset_amount_satoshi,
blinding_factor=Uint256(lx(asset_utxo['amountblinder'])),
asset_blinding_factor=Uint256(lx(asset_utxo['assetblinder'])))
],
output_pubkeys=[alice_addr.blinding_pubkey],
auxiliary_generators=assetcommitments)
# The blinding must succeed!
if blind_result.error:
die('blind failed: {}'.format(blind_result.error))
# And must blind exactly one output
if blind_result.num_successfully_blinded != 1:
die('blinded {} outputs, expected to be 1'.format(
blind_result.num_successfully_blinded))
say('Successfully blinded partial transaction, sending it to Alice')
send('partial_blinded_tx', partial_tx.serialize())
say("Generating addresses to receive Alice's assets")
# Generate as many destination addresses as there are assets
# in Alice's offer. Record blinding keys for the addresses.
our_addrs = []
blinding_keys = []
for _ in alice_offers:
addr, blinding_key = get_dst_addr(say, rpc)
our_addrs.append(str(addr))
blinding_keys.append(blinding_key)
say("Sending my addresses and assetcommitment to Alice")
send('addr_list_and_assetcommitment',
(our_addrs, asset_utxo['assetcommitment']))
semi_signed_tx_bytes = recv('partially_signed_tx')
say('Got partially signed tx of size {} bytes from Alice'.format(
len(semi_signed_tx_bytes)))
semi_signed_tx = CTransaction.deserialize(semi_signed_tx_bytes)
# Transaction should have 3 extra outputs - one output to Alice,
# fee output, and fee asset change output
if len(semi_signed_tx.vout) != len(alice_offers) + 3:
die('unexpected number of outputs in tx from Alice: '
'expected {}, got {}'.format(
len(alice_offers) + 3, len(semi_signed_tx.vout)))
if not semi_signed_tx.vout[-1].is_fee():
die('Last output in tx from Alice '
'is expected to be fee output, but it is not')
# Unblind outputs that should be directed to us and check
# that they match the offer. We use n+1 as output index
# because we skip our own output, which is at index 0.
for n, offer in enumerate(alice_offers):
result = semi_signed_tx.vout[n + 1].unblind_confidential_pair(
blinding_keys[n], semi_signed_tx.wit.vtxoutwit[n + 1].rangeproof)
if result.error:
die('cannot unblind output {} that should have been '
'directed to us: {}'.format(n + 1, result.error))
if result.asset.to_hex() != offer.asset:
die("asset at position {} (vout {}) in partial transaction "
"from Alice {} is not the same as asset in Alice's "
"initial offer ({})".format(n, n + 1, result.asset.to_hex(),
offer.asset))
if result.amount != offer.amount:
die("amount at position {} (vout {}) in partial transaction "
"from Alice {} is not the same as amount in Alice's "
"initial offer ({})".format(n, n + 1, result.amount,
offer.amount))
say("Assets and amounts in partially signed transaction "
"match Alice's offer")
# Signing will change the tx, so i
tx = semi_signed_tx.to_mutable()
# Our input is at index 0
sign_input(tx, 0, asset_utxo)
# Note that at this point both participants can still opt out of the swap:
# Bob by not broadcasting the transaction, and Alice by double-spending
# her inputs to the transaction. Bob still have tiny advantage, because
# he can pretend to have 'difficulties' in broadcasting and try to exploit
# Alice's patience
say('Signed the transaction from my side, ready to send')
tx_hex = b2x(tx.serialize())
if bob_be_sneaky:
say('Hey! I am now in control of the final transaction. '
'I have the option to exectue the swap or abort. ')
say('Why not wait a bit and watch asset prices, and execute '
'the swap only if it is profitable')
say('I will reduce my risk a bit by doing that.')
# Bob takes his time and is not sending the final
# transaction to Alice for some time...
time.sleep(ALICE_PATIENCE_LIMIT + 2)
say('OK, I am willing to execute the swap now')
# Send the final transaction to Alice, so she can be sure that
# we is not cheating
send('final-signed-tx', tx_hex)
txid = rpc.sendrawtransaction(tx_hex)
say('Sent with txid {}'.format(txid))
# Wait for alice to politely end the conversation
recv('thanks-goodbye')
print_asset_balances(say, alice_offers + [my_offer], rpc)
for i, offer in enumerate(alice_offers):
balance = coins_to_satoshi(rpc.getbalance("*", 1, False, offer.asset))
if balance != offer.amount:
die('something went wrong, asset{} balance after swap should be '
'{} satoshi, but it is {} satoshi'.format(
i, balance, offer.amount))
say('Asset atomic swap completed successfully')
# An array of blinding pubkeys that we will supply to tx.blind()
# It should cover all the outputs of the resulting transaction.
output_pubkeys = []
if isinstance(dst_addr, CCoinConfidentialAddress):
output_pubkeys.append(dst_addr.blinding_pubkey)
else:
output_pubkeys.append(CPubKey())
# Construct a transaction that spends the output we found
# to the given destination address.
# Note that the CTransaction is just a frontend for convenience,
# and the created object will be the instance of the
# CElementsTransaction class. The same with CTxIn, CTxOut, etc.
tx = CElementsTransaction(
vin=[CTxIn(prevout=COutPoint(hash=input_tx.GetTxid(), n=utxo_n))],
vout=[
CElementsTxOut(nValue=CConfidentialValue(dst_value),
nAsset=CConfidentialAsset(asset_to_spend),
scriptPubKey=dst_addr.to_scriptPubKey()),
# Fee output must be explicit in Elements
CElementsTxOut(nValue=CConfidentialValue(fee_value),
nAsset=fee_asset)
])
# Add empty pubkey for fee output
output_pubkeys.append(CPubKey())
# We cannot blind an immutable transaction. Make it mutable.
tx = tx.to_mutable()
}
prevouts_by_scriptPubKey = None
if not args.dryrun:
txid = rpc.sendmany(
'', {
adr: float(float(amount) / CoreCoinParams.COIN)
for adr, amount in payments.items()
}, 0)
logging.info('Sent pre-pub tx: %s' % txid)
tx = CTransaction.deserialize(x(rpc.getrawtransaction(txid)))
prevouts_by_scriptPubKey = {
txout.scriptPubKey: COutPoint(lx(txid), i)
for i, txout in enumerate(tx.vout)
}
else:
prevouts_by_scriptPubKey = {
redeemScript.to_p2sh_scriptPubKey(): COutPoint(b'\x00' * 32, i)
for i, (scriptSig, redeemScript) in enumerate(scripts)
}
logging.debug('Payments: %r' % payments)
logging.info(
'Total cost: %s BTC' %
str_money_value(sum(amount for addr, amount in payments.items())))
# Create unsigned tx for SignatureHash
vout = [CTxOut(0, CScript([OP_RETURN]))]
except FileNotFoundError as exp:
if len(f) / 2 in (20, 32):
digests.append(x(f))
else:
raise exp
except IOError as exp:
print(exp, file=sys.stderr)
continue
for digest in digests:
txouts = []
unspent = sorted(rpc.listunspent(0), key=lambda x: hash(x['amount']))
txins = [
CTxIn(COutPoint(lx(unspent[-1]['txid']), int(unspent[-1]['vout'])))
]
value_in = coins_to_satoshi(unspent[-1]['amount'])
change_addr = rpc.getnewaddress()
change_pubkey_hex = rpc.getaddressinfo(change_addr)['pubkey']
change_out = CMutableTxOut(
CoreCoinParams.MAX_MONEY,
CScript([x(change_pubkey_hex), OP_CHECKSIG]))
digest_outs = [CMutableTxOut(0, CScript([OP_RETURN, digest]))]
txouts = [change_out] + digest_outs
tx = CTransaction(txins, txouts).to_mutable()
def test_clone(self):
outpoint = COutPoint(
lx('4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b'
), 0)
self.assertEqual(outpoint.serialize(), outpoint.clone().serialize())