def test_MoneyRangeCustomParams(self):
class CoreHighMaxClassDispatcher(CoreBitcoinClassDispatcher):
...
class CoreHighMaxParams(CoreBitcoinParams, CoreBitcoinClass):
@classgetter
def MAX_MONEY(self):
return 22000000 * self.COIN
class WalletHighMaxClassDispatcher(WalletBitcoinClassDispatcher):
...
class HighMaxParams(BitcoinMainnetParams):
NAME = 'high_maxmoney'
WALLET_DISPATCHER = WalletHighMaxClassDispatcher
with ChainParams(HighMaxParams):
self.assertFalse(MoneyRange(-1))
with self.assertRaises(ValueError):
coins_to_satoshi(-1)
with self.assertRaises(ValueError):
satoshi_to_coins(-1)
self.assertTrue(MoneyRange(0))
self.assertTrue(MoneyRange(100000))
max_satoshi = coins_to_satoshi(22000000)
self.assertTrue(
MoneyRange(max_satoshi)) # Maximum money on Bitcoin network
self.assertFalse(MoneyRange(max_satoshi + 1))
with self.assertRaises(ValueError):
coins_to_satoshi(max_satoshi + 1)
with self.assertRaises(ValueError):
satoshi_to_coins(max_satoshi + 1)
def test_p2wsh_signaturehash2(self):
unsigned_tx = x(
'0100000002e9b542c5176808107ff1df906f46bb1f2583b16112b95ee5380665ba7fcfc0010000000000ffffffff80e68831516392fcd100d186b3c2c7b95c80b53c77e77c35ba03a66b429a2a1b0000000000ffffffff0280969800000000001976a914de4b231626ef508c9a74a8517e6783c0546d6b2888ac80969800000000001976a9146648a8cd4531e1ec47f35916de8e259237294d1e88ac00000000'
)
value1 = coins_to_satoshi(0.16777215)
scriptcode1 = CScript(
x('0063ab68210392972e2eb617b2388771abe27235fd5ac44af8e61693261550447a4c3e39da98ac'
))
value2 = coins_to_satoshi(0.16777215)
scriptcode2 = CScript(
x('68210392972e2eb617b2388771abe27235fd5ac44af8e61693261550447a4c3e39da98ac'
))
self.assertEqual(
SignatureHash(scriptcode1, CTransaction.deserialize(unsigned_tx),
0, SIGHASH_SINGLE | SIGHASH_ANYONECANPAY, value1,
SIGVERSION_WITNESS_V0),
x('e9071e75e25b8a1e298a72f0d2e9f4f95a0f5cdf86a533cda597eb402ed13b3a'
))
self.assertEqual(
SignatureHash(scriptcode2, CTransaction.deserialize(unsigned_tx),
1, SIGHASH_SINGLE | SIGHASH_ANYONECANPAY, value2,
SIGVERSION_WITNESS_V0),
x('cd72f1f1a433ee9df816857fad88d8ebd97e09a75cd481583eb841c330275e54'
))
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 find_utxo_for_fee(say, die, rpc):
"""Find suitable utxo to pay the fee.
Retrieve thekey to spend this utxo and add it to
the returned dict."""
# Find utxo to use for fee. In our simple example, only Alice pays the fee.
# To be on a safe side, include only transactions
# that are confirmed (1 as 'minconf' argument of listunspent)
# and safe to spend (False as 'include_unsafe' # argument of listunspent)
say('Searching for utxo for fee asset')
utxo_list = rpc.listunspent(1, 9999999, [], False,
{'asset': fee_asset.to_hex()})
utxo_list.sort(key=lambda u: u['amount'])
for utxo in utxo_list:
# To not deal with possibility of dust outputs,
# just require fee utxo to be big enough
if coins_to_satoshi(utxo['amount']) >= FIXED_FEE_SATOSHI * 2:
utxo['key'] = CCoinKey(rpc.dumpprivkey(utxo['address']))
if 'assetcommitment' not in utxo:
# If UTXO is not blinded, Elements daemon will not
# give us assetcommitment, so we need to generate it ourselves.
asset = CAsset(lx(utxo['asset']))
utxo['assetcommitment'] = b2x(asset.to_commitment())
return utxo
else:
die('Cannot find utxo for fee that is >= {} satoshi'.format(
FIXED_FEE_SATOSHI * 2))
def test_MoneyRange(self):
self.assertFalse(MoneyRange(-1))
with self.assertRaises(ValueError):
coins_to_satoshi(-1)
with self.assertRaises(ValueError):
satoshi_to_coins(-1)
self.assertTrue(MoneyRange(0))
self.assertTrue(MoneyRange(100000))
max_satoshi = coins_to_satoshi(21000000)
self.assertTrue(
MoneyRange(max_satoshi)) # Maximum money on Bitcoin network
self.assertFalse(MoneyRange(max_satoshi + 1))
with self.assertRaises(ValueError):
coins_to_satoshi(max_satoshi + 1)
with self.assertRaises(ValueError):
satoshi_to_coins(max_satoshi + 1)
def check_unblind(self, unblinded_tx, unblinded_tx_raw, blinded_tx,
blinded_tx_raw, bundle, blinding_derivation_key):
for n, bvout in enumerate(blinded_tx.vout):
uvout = unblinded_tx.vout[n]
if not uvout.nValue.is_explicit():
# skip confidential vouts of partially-blinded txs
continue
self.assertEqual(bvout.scriptPubKey, uvout.scriptPubKey)
if bvout.nAsset.is_explicit():
self.assertTrue(bvout.nValue.is_explicit())
self.assertEqual(bvout.nValue.to_amount(),
uvout.nValue.to_amount())
self.assertEqual(bvout.nAsset.to_asset().data,
uvout.nAsset.to_asset().data)
self.assertEqual(bvout.nNonce.commitment,
uvout.nNonce.commitment)
else:
self.assertFalse(bvout.nValue.is_explicit())
for fbk, spk_set in bundle['foreign_blinding_keys'].items():
if b2x(bvout.scriptPubKey) in spk_set:
blinding_key = uvout.scriptPubKey.derive_blinding_key(
CKey(lx(fbk)))
break
else:
blinding_key = uvout.scriptPubKey.derive_blinding_key(
blinding_derivation_key)
unblind_result = bvout.unblind_confidential_pair(
blinding_key=blinding_key,
rangeproof=blinded_tx.wit.vtxoutwit[n].rangeproof)
self.assertFalse(unblind_result.error)
self.assertEqual(uvout.nValue.to_amount(),
unblind_result.amount)
self.assertEqual(uvout.nAsset.to_asset().data,
unblind_result.asset.data)
descr = unblind_result.get_descriptor()
self.assertIsInstance(descr, BlindingInputDescriptor)
self.assertEqual(descr.amount, unblind_result.amount)
self.assertEqual(descr.asset, unblind_result.asset)
self.assertEqual(descr.blinding_factor,
unblind_result.blinding_factor)
self.assertEqual(descr.asset_blinding_factor,
unblind_result.asset_blinding_factor)
ub_info = bundle['unblinded_vout_info'][n]
if len(ub_info):
self.assertEqual(coins_to_satoshi(ub_info['amount']),
unblind_result.amount)
self.assertEqual(ub_info['asset'],
unblind_result.asset.to_hex())
self.assertEqual(ub_info['blinding_factor'],
unblind_result.blinding_factor.to_hex())
self.assertEqual(
ub_info['asset_blinding_factor'],
unblind_result.asset_blinding_factor.to_hex())
def sign_input(tx, input_index, utxo):
"""Sign an input of transaction.
Single-signature signing with SIGHASH_ALL"""
key = utxo['key']
src_addr = CCoinAddress(utxo['address'])
script_for_sighash = CScript(
[OP_DUP, OP_HASH160,
Hash160(key.pub), OP_EQUALVERIFY, OP_CHECKSIG])
assert isinstance(src_addr, (P2PKHCoinAddress, P2SHCoinAddress,
P2WPKHCoinAddress)),\
'only p2pkh, p2wpkh and p2sh_p2wpkh addresses are supported'
if isinstance(src_addr, P2PKHCoinAddress):
sigversion = SIGVERSION_BASE
else:
sigversion = SIGVERSION_WITNESS_V0
if 'amountcommitment' in utxo:
amountcommitment = CConfidentialValue(x(utxo['amountcommitment']))
else:
amountcommitment = CConfidentialValue(coins_to_satoshi(utxo['amount']))
sighash = script_for_sighash.sighash(tx,
input_index,
SIGHASH_ALL,
amount=amountcommitment,
sigversion=sigversion)
sig = key.sign(sighash) + bytes([SIGHASH_ALL])
if isinstance(src_addr, P2PKHCoinAddress):
tx.vin[input_index].scriptSig = CScript(
[CScript(sig), CScript(key.pub)])
scriptpubkey = src_addr.to_scriptPubKey()
elif isinstance(src_addr, P2WPKHCoinAddress):
tx.vin[input_index].scriptSig = CScript()
tx.wit.vtxinwit[input_index] = CTxInWitness(
CScriptWitness([CScript(sig), CScript(key.pub)]))
scriptpubkey = src_addr.to_scriptPubKey()
else:
# Assume that this is p2sh-wrapped p2wpkh address
inner_scriptPubKey = CScript([0, Hash160(key.pub)])
tx.vin[input_index].scriptSig = CScript([inner_scriptPubKey])
tx.wit.vtxinwit[input_index] = CTxInWitness(
CScriptWitness([CScript(sig), CScript(key.pub)]))
scriptpubkey = inner_scriptPubKey.to_p2sh_scriptPubKey()
VerifyScript(tx.vin[input_index].scriptSig,
scriptpubkey,
tx,
input_index,
amount=amountcommitment,
flags=(SCRIPT_VERIFY_P2SH, ))
def check_sign(self, blinded_tx: CTransaction, signed_tx: CTransaction,
bundle: Dict[str, Any]) -> None:
tx_to_sign = blinded_tx.to_mutable()
for n, vin in enumerate(tx_to_sign.vin):
utxo = bundle['vin_utxo'][n]
amount = -1 if utxo['amount'] == -1 else coins_to_satoshi(
utxo['amount'])
scriptPubKey = CScript(x(utxo['scriptPubKey']))
a = CCoinAddress(utxo['address'])
if 'privkey' in utxo:
privkey = CCoinKey(utxo['privkey'])
assert isinstance(a, P2PKHCoinAddress),\
"only P2PKH is supported for single-sig"
assert a == P2PKHElementsAddress.from_pubkey(privkey.pub)
assert scriptPubKey == a.to_scriptPubKey()
sighash = SignatureHash(scriptPubKey,
tx_to_sign,
n,
SIGHASH_ALL,
amount=amount,
sigversion=SIGVERSION_BASE)
sig = privkey.sign(sighash) + bytes([SIGHASH_ALL])
tx_to_sign.vin[n].scriptSig = CScript(
[CScript(sig), CScript(privkey.pub)])
else:
pk_list = [CCoinKey(pk) for pk in utxo['privkey_list']]
redeem_script_data = [utxo['num_p2sh_participants']]
redeem_script_data.extend([pk.pub for pk in pk_list])
redeem_script_data.extend([len(pk_list), OP_CHECKMULTISIG])
redeem_script = CScript(redeem_script_data)
assert isinstance(a, P2SHCoinAddress),\
"only P2SH is supported for multi-sig."
assert scriptPubKey == redeem_script.to_p2sh_scriptPubKey()
assert a == P2SHElementsAddress.from_scriptPubKey(
redeem_script.to_p2sh_scriptPubKey())
sighash = SignatureHash(redeem_script,
tx_to_sign,
n,
SIGHASH_ALL,
amount=amount,
sigversion=SIGVERSION_BASE)
sigs = [
pk.sign(sighash) + bytes([SIGHASH_ALL]) for pk in pk_list
]
tx_to_sign.vin[n].scriptSig = CScript([b''] + sigs +
[redeem_script])
VerifyScript(tx_to_sign.vin[n].scriptSig,
scriptPubKey,
tx_to_sign,
n,
amount=amount)
self.assertEqual(tx_to_sign.serialize(), signed_tx.serialize())
def test_p2wpkh_signaturehash(self):
unsigned_tx = x(
'0100000002fff7f7881a8099afa6940d42d1e7f6362bec38171ea3edf433541db4e4ad969f0000000000eeffffffef51e1b804cc89d182d279655c3aa89e815b1b309fe287d9b2b55d57b90ec68a0100000000ffffffff02202cb206000000001976a9148280b37df378db99f66f85c95a783a76ac7a6d5988ac9093510d000000001976a9143bde42dbee7e4dbe6a21b2d50ce2f0167faa815988ac11000000'
)
scriptpubkey = CScript(
x('00141d0f172a0ecb48aee1be1f2687d2963ae33f71a1'))
value = coins_to_satoshi(6)
address = CBech32BitcoinAddress.from_scriptPubKey(scriptpubkey)
self.assertEqual(
SignatureHash(address.to_redeemScript(),
CTransaction.deserialize(unsigned_tx), 1,
SIGHASH_ALL, value, SIGVERSION_WITNESS_V0),
x('c37af31116d1b27caf68aae9e3ac82f1477929014d5b917657d0eb49478cb670'
))
def test_p2sh_p2wpkh_signaturehash(self):
unsigned_tx = x(
'0100000001db6b1b20aa0fd7b23880be2ecbd4a98130974cf4748fb66092ac4d3ceb1a54770100000000feffffff02b8b4eb0b000000001976a914a457b684d7f0d539a46a45bbc043f35b59d0d96388ac0008af2f000000001976a914fd270b1ee6abcaea97fea7ad0402e8bd8ad6d77c88ac92040000'
)
scriptpubkey = CScript(
x('001479091972186c449eb1ded22b78e40d009bdf0089'))
value = coins_to_satoshi(10)
address = CCoinAddress.from_scriptPubKey(scriptpubkey)
self.assertEqual(
SignatureHash(address.to_redeemScript(),
CTransaction.deserialize(unsigned_tx), 0,
SIGHASH_ALL, value, SIGVERSION_WITNESS_V0),
x('64f3b0f4dd2bb3aa1ce8566d220cc74dda9df97d8490cc81d89d735c92e59fb6'
))
def test_p2sh_p2wsh_signaturehash(self):
unsigned_tx = x(
'010000000136641869ca081e70f394c6948e8af409e18b619df2ed74aa106c1ca29787b96e0100000000ffffffff0200e9a435000000001976a914389ffce9cd9ae88dcc0631e88a821ffdbe9bfe2688acc0832f05000000001976a9147480a33f950689af511e6e84c138dbbd3c3ee41588ac00000000'
)
value = coins_to_satoshi(9.87654321)
witnessscript = CScript(
x('56210307b8ae49ac90a048e9b53357a2354b3334e9c8bee813ecb98e99a7e07e8c3ba32103b28f0c28bfab54554ae8c658ac5c3e0ce6e79ad336331f78c428dd43eea8449b21034b8113d703413d57761b8b9781957b8c0ac1dfe69f492580ca4195f50376ba4a21033400f6afecb833092a9a21cfdf1ed1376e58c5d1f47de74683123987e967a8f42103a6d48b1131e94ba04d9737d61acdaa1322008af9602b3b14862c07a1789aac162102d8b661b0b3302ee2f162b09e07a55ad5dfbe673a9f01d9f0c19617681024306b56ae'
))
self.assertEqual(
SignatureHash(witnessscript, CTransaction.deserialize(unsigned_tx),
0, SIGHASH_ALL, value, SIGVERSION_WITNESS_V0),
x('185c0be5263dce5b4bb50a047973c1b6272bfbd0103a89444597dc40b248ee7c'
))
self.assertEqual(
SignatureHash(witnessscript, CTransaction.deserialize(unsigned_tx),
0, SIGHASH_NONE, value, SIGVERSION_WITNESS_V0),
x('e9733bc60ea13c95c6527066bb975a2ff29a925e80aa14c213f686cbae5d2f36'
))
self.assertEqual(
SignatureHash(witnessscript, CTransaction.deserialize(unsigned_tx),
0, SIGHASH_SINGLE, value, SIGVERSION_WITNESS_V0),
x('1e1f1c303dc025bd664acb72e583e933fae4cff9148bf78c157d1e8f78530aea'
))
self.assertEqual(
SignatureHash(witnessscript, CTransaction.deserialize(unsigned_tx),
0, SIGHASH_ALL | SIGHASH_ANYONECANPAY, value,
SIGVERSION_WITNESS_V0),
x('2a67f03e63a6a422125878b40b82da593be8d4efaafe88ee528af6e5a9955c6e'
))
self.assertEqual(
SignatureHash(witnessscript, CTransaction.deserialize(unsigned_tx),
0, SIGHASH_NONE | SIGHASH_ANYONECANPAY, value,
SIGVERSION_WITNESS_V0),
x('781ba15f3779d5542ce8ecb5c18716733a5ee42a6f51488ec96154934e2c890a'
))
self.assertEqual(
SignatureHash(witnessscript, CTransaction.deserialize(unsigned_tx),
0, SIGHASH_SINGLE | SIGHASH_ANYONECANPAY, value,
SIGVERSION_WITNESS_V0),
x('511e8e52ed574121fc1b654970395502128263f62662e076dc6baf05c2e6a99b'
))
def test_MoneyRangeCustomParams(self) -> None:
class CoreHighMaxClassDispatcher(CoreBitcoinClassDispatcher):
...
class CoreHighMaxClass(CoreBitcoinClass,
metaclass=CoreHighMaxClassDispatcher):
...
class CoreHighMaxParams(CoreBitcoinParams, CoreHighMaxClass):
@classgetter
def MAX_MONEY(self) -> int:
return 10**100 * self.COIN
class WalletHighMaxClassDispatcher(WalletBitcoinClassDispatcher,
depends=[
CoreHighMaxClassDispatcher
]):
...
class HighMaxParams(BitcoinMainnetParams):
NAME = 'high_maxmoney'
WALLET_DISPATCHER = WalletHighMaxClassDispatcher
with self.assertRaises(ValueError):
coins_to_satoshi(10**100)
with ChainParams(HighMaxParams):
self.assertFalse(MoneyRange(-1))
with self.assertRaises(ValueError):
coins_to_satoshi(-1)
with self.assertRaises(ValueError):
satoshi_to_coins(-1)
self.assertTrue(MoneyRange(0))
self.assertTrue(MoneyRange(100000))
max_satoshi = coins_to_satoshi(10**100)
self.assertEqual(satoshi_to_coins(max_satoshi), 10**100)
self.assertTrue(MoneyRange(max_satoshi))
self.assertFalse(MoneyRange(max_satoshi + 1))
with self.assertRaises(ValueError):
coins_to_satoshi(max_satoshi + 1)
with self.assertRaises(ValueError):
satoshi_to_coins(max_satoshi + 1)
def test_p2wsh_signaturehash1(self):
unsigned_tx = x(
'0100000002fe3dc9208094f3ffd12645477b3dc56f60ec4fa8e6f5d67c565d1c6b9216b36e0000000000ffffffff0815cf020f013ed6cf91d29f4202e8a58726b1ac6c79da47c23d1bee0a6925f80000000000ffffffff0100f2052a010000001976a914a30741f8145e5acadf23f751864167f32e0963f788ac00000000'
)
value2 = coins_to_satoshi(49)
scriptcode1 = CScript(
x('21026dccc749adc2a9d0d89497ac511f760f45c47dc5ed9cf352a58ac706453880aeadab210255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465ac'
))
# This is the same script with everything up to the last executed OP_CODESEPARATOR, including that
# OP_CODESEPARATOR removed
scriptcode2 = CScript(
x('210255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465ac'
))
self.assertEqual(
SignatureHash(scriptcode1, CTransaction.deserialize(unsigned_tx),
1, SIGHASH_SINGLE, value2, SIGVERSION_WITNESS_V0),
x('82dde6e4f1e94d02c2b7ad03d2115d691f48d064e9d52f58194a6637e4194391'
))
self.assertEqual(
SignatureHash(scriptcode2, CTransaction.deserialize(unsigned_tx),
1, SIGHASH_SINGLE, value2, SIGVERSION_WITNESS_V0),
x('fef7bd749cce710c5c052bd796df1af0d935e59cea63736268bcbe2d2134fc47'
))
# 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(
coins_to_satoshi(0.001),
CBitcoinAddress('1C7zdTfnkzmr13HfA2vNm5SJYRK6nEKyq8').to_scriptPubKey())
# Create the unsigned transaction.
tx = CMutableTransaction([txin], [txout])
# Calculate the signature hash for that transaction.
sighash = SignatureHash(txin_scriptPubKey, tx, 0, SIGHASH_ALL)
# Now sign it. We have to append the type of signature we want to the end, in
# this case the usual SIGHASH_ALL.
sig = seckey.sign(sighash) + bytes([SIGHASH_ALL])
# Set the scriptSig of our transaction input appropriately.
txin.scriptSig = CScript([sig, seckey.pub])
import sys
PATH_TO_FUNCTIONAL = "~/bitcoin/test/functional"
PATH_TO_BITCOINTX = "~/python-bitcointx"
TEST_DATADIR = "tests/data"
sys.path.insert(0, PATH_TO_BITCOINTX)
sys.path.insert(0, PATH_TO_FUNCTIONAL)
from bitcointx import select_chain_params
from bitcointx.core import coins_to_satoshi
select_chain_params("bitcoin/regtest")
MIN_FEE = coins_to_satoshi(0.00000169)
TIMELOCK = 3
PORTION_TO_VAULT = 0.1
def alice(say, recv, send, die, btc_rpc, elt_rpc):
"""A function that implements the logic
of the Elements-side participant
of confidential cross-chain atomic swap"""
global last_wish_func
# Default chain for Alice will be Elements
# To handle bitcoin-related objects, either
# `with ChainParams(bitcoin_chain_name):` have to be used, or
# concrete classes, like CBitcoinAddress, CBitcoinTransaction, etc.
select_chain_params(elements_chain_name)
# Let's create the shared blinding key
blinding_key = CKey.from_secret_bytes(os.urandom(32))
# And the key for btc spend
alice_btc_key = CKey.from_secret_bytes(os.urandom(32))
# And the key for the 'timeout' branch of the contract
alice_elt_exit_key = CKey.from_secret_bytes(os.urandom(32))
say('Sending pubkeys to Bob')
send('pubkeys', (alice_btc_key.pub, alice_elt_exit_key.pub))
say('Sending the blinding key to Bob')
send('blinding_key', blinding_key.secret_bytes)
(contract_pubkey_raw, bob_elt_pubkey_raw,
bob_btc_exit_pub_raw) = recv('pubkeys')
say("Pubkey of the key to be revealed: {}".format(
b2x(contract_pubkey_raw)))
say("Bob's Elements-side pubkey: {}".format(b2x(bob_elt_pubkey_raw)))
contract_pubkey = CPubKey(contract_pubkey_raw)
key_to_reveal_pub = CPubKey.add(contract_pubkey, blinding_key.pub)
elt_contract = make_elt_cntract(key_to_reveal_pub, bob_elt_pubkey_raw,
alice_elt_exit_key.pub)
elt_contract_addr = P2SHCoinAddress.from_redeemScript(elt_contract)
confidential_contract_addr = P2SHCoinConfidentialAddress.from_unconfidential(
elt_contract_addr, blinding_key.pub)
assert isinstance(confidential_contract_addr, CElementsConfidentialAddress)
say("Created Elemets-side swap contract, size: {}".format(
len(elt_contract)))
say("Contract address:\n\tconfidential: {}\n\tunconfidential: {}".format(
confidential_contract_addr, elt_contract_addr))
btc_txid = recv('btc_txid')
combined_btc_spend_pubkey = CPubKey.add(contract_pubkey, alice_btc_key.pub)
btc_contract = make_btc_contract(combined_btc_spend_pubkey,
bob_btc_exit_pub_raw)
tx_json = btc_rpc.getrawtransaction(btc_txid, 1)
if tx_json['confirmations'] < 6:
die('Transaction does not have enough confirmations')
# We use ChainParams, and not P2WSHBitcoinAddress here,
# because bitcoin_chain_name might be 'bitcoin/regtest', for example,
# and then the address would need to be P2WSHBitcoinRegtestAddress.
# with ChainParams we leverage the 'frontend class' magic, P2WSHCoinAddress
# will give us appropriate instance.
with ChainParams(bitcoin_chain_name):
btc_contract_addr = P2WSHCoinAddress.from_redeemScript(btc_contract)
say('Looking for this address in transaction {} in Bitcoin'.format(
btc_txid))
# CTransaction subclasses do not change between mainnet/testnet/regtest,
# so we can directly use CBitcoinTransaction.
# That might not be true for other chains, though.
# You might also want to use CTransaction within `with ChainParams(...):`
btc_tx = CBitcoinTransaction.deserialize(x(tx_json['hex']))
for n, vout in enumerate(btc_tx.vout):
if vout.scriptPubKey == btc_contract_addr.to_scriptPubKey():
say("Found the address at output {}".format(n))
btc_vout_n = n
break
else:
die('Did not find contract address in transaction')
if vout.nValue != coins_to_satoshi(pre_agreed_amount):
die('the amount {} found at the output in the offered transaction '
'does not match the expected amount {}'.format(
satoshi_to_coins(vout.nValue), pre_agreed_amount))
say('Bitcoin amount match expected values')
say('Sending {} to {}'.format(pre_agreed_amount,
confidential_contract_addr))
contract_txid = elt_rpc.sendtoaddress(str(confidential_contract_addr),
pre_agreed_amount)
def alice_last_wish_func():
try_reclaim_elt(say, elt_rpc, contract_txid, elt_contract,
alice_elt_exit_key, blinding_key, die)
last_wish_func = alice_last_wish_func
wait_confirm(say, 'Elements', contract_txid, die, elt_rpc, num_confirms=2)
send('elt_txid', contract_txid)
sr_txid = wait_spend_reveal_transaction(say, contract_txid, die, elt_rpc)
say('Got txid for spend-reveal transaction from Bob ({})'.format(sr_txid))
tx_json = elt_rpc.getrawtransaction(sr_txid, 1)
wait_confirm(say, 'Elements', sr_txid, die, elt_rpc, num_confirms=2)
sr_tx = CTransaction.deserialize(x(tx_json['hex']))
for n, vin in enumerate(sr_tx.vin):
if vin.prevout.hash == lx(contract_txid)\
and vin.scriptSig[-(len(elt_contract)):] == elt_contract:
say('Transaction input {} seems to contain a script '
'we can recover the key from'.format(n))
reveal_script_iter = iter(vin.scriptSig)
break
else:
die('Spend-reveal transaction does not have input that spends '
'the contract output')
next(reveal_script_iter) # skip Bob's spend signature
try:
# 2 skipped bytes are tag and len
sig_s = ecdsa.util.string_to_number(next(reveal_script_iter)[2:])
except (ValueError, StopIteration):
die('Reveal script is invalid')
k, r = get_known_k_r()
order = ecdsa.SECP256k1.order
mhash = ecdsa.util.string_to_number(hashlib.sha256(b'\x01').digest())
r_inverse = ecdsa.numbertheory.inverse_mod(r, order)
for s in (-sig_s, sig_s):
secret_exponent = (((s * k - mhash) % order) * r_inverse) % order
recovered_key = CKey.from_secret_bytes(
ecdsa.util.number_to_string(secret_exponent, order))
if recovered_key.pub == key_to_reveal_pub:
break
else:
die('Key recovery failed. Should not happen - the sig was already '
'verified when transaction was accepted into mempool. '
'Must be a bug.')
say('recovered key pubkey: {}'.format(b2x(recovered_key.pub)))
contract_key = CKey.sub(recovered_key, blinding_key)
say('recovered unblined key pubkey: {}'.format(b2x(contract_key.pub)))
combined_btc_spend_key = CKey.add(contract_key, alice_btc_key)
say('Successfully recovered the key. Can now spend Bitcoin from {}'.format(
btc_contract_addr))
with ChainParams(bitcoin_chain_name):
dst_addr = CCoinAddress(btc_rpc.getnewaddress())
btc_claim_tx = create_btc_spend_tx(dst_addr,
btc_txid,
btc_vout_n,
btc_contract,
spend_key=combined_btc_spend_key)
say('Sending my Bitcoin-claim transaction')
btc_claim_txid = btc_rpc.sendrawtransaction(b2x(btc_claim_tx.serialize()))
wait_confirm(say, 'Bitcoin', btc_claim_txid, die, btc_rpc, num_confirms=3)
say('Got my Bitcoin. Swap successful!')
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, btc_rpc, elt_rpc):
"""A function that implements the logic
of the Bitcoin-side participant
of confidential cross-chain atomic swap"""
global last_wish_func
# Default chain for Bob will be Bitcoin
# To handle bitcoin-related objects, either
# `with ChainParams(elements_chain_name):` have to be used, or
# concrete classes, like CElementsAddress, CElementsTransaction, etc.
select_chain_params(bitcoin_chain_name)
say('Waiting for blinding key from Alice')
alice_btc_pub_raw, alice_elt_exit_pub_raw = recv('pubkeys')
blinding_key = CKey.from_secret_bytes(recv('blinding_key'))
say("Pubkey for blinding key: {}".format(b2x(blinding_key.pub)))
# Let's create the key that would lock the coins on Bitcoin side
contract_key = CKey.from_secret_bytes(os.urandom(32))
# And the key for Elements side
bob_elt_spend_key = CKey.from_secret_bytes(os.urandom(32))
# And the key for 'timeout' case on btc side
bob_btc_exit_key = CKey.from_secret_bytes(os.urandom(32))
key_to_reveal_pub = CPubKey.add(contract_key.pub, blinding_key.pub)
say("The pubkey of the combined key to be revealed: {}".format(
b2x(key_to_reveal_pub)))
say('Sending my pubkeys to Alice')
send('pubkeys',
(contract_key.pub, bob_elt_spend_key.pub, bob_btc_exit_key.pub))
combined_btc_spend_pubkey = CPubKey.add(contract_key.pub,
CPubKey(alice_btc_pub_raw))
say('combined_btc_spend_pubkey: {}'.format(b2x(combined_btc_spend_pubkey)))
btc_contract = make_btc_contract(combined_btc_spend_pubkey,
bob_btc_exit_key.pub)
btc_contract_addr = P2WSHCoinAddress.from_redeemScript(btc_contract)
say("Created Bitcoin-side swap contract, size: {}".format(
len(btc_contract)))
say("Contract address: {}".format(btc_contract_addr))
say('Sending {} to {}'.format(pre_agreed_amount, btc_contract_addr))
btc_txid = btc_rpc.sendtoaddress(str(btc_contract_addr), pre_agreed_amount)
def bob_last_wish_func():
try_reclaim_btc(say, btc_rpc, btc_txid, btc_contract, bob_btc_exit_key,
die)
last_wish_func = bob_last_wish_func
wait_confirm(say, 'Bitcoin', btc_txid, die, btc_rpc, num_confirms=6)
send('btc_txid', btc_txid)
elt_txid = recv('elt_txid')
elt_contract = make_elt_cntract(key_to_reveal_pub, bob_elt_spend_key.pub,
alice_elt_exit_pub_raw)
with ChainParams(elements_chain_name):
elt_contract_addr = P2SHCoinAddress.from_redeemScript(elt_contract)
say('Got Elements contract address from Alice: {}'.format(
elt_contract_addr))
say('Looking for this address in transaction {} in Elements'.format(
elt_txid))
tx_json = elt_rpc.getrawtransaction(elt_txid, 1)
if tx_json['confirmations'] < 2:
die('Transaction does not have enough confirmations')
elt_commit_tx = CElementsTransaction.deserialize(x(tx_json['hex']))
vout_n, unblind_result = find_and_unblind_vout(say, elt_commit_tx,
elt_contract_addr,
blinding_key, die)
if unblind_result.amount != coins_to_satoshi(pre_agreed_amount):
die('the amount {} found at the output in the offered transaction '
'does not match the expected amount {}'.format(
satoshi_to_coins(unblind_result.amount), pre_agreed_amount))
say('The asset and amount match expected values. lets spend it.')
with ChainParams(elements_chain_name):
dst_addr = CCoinAddress(elt_rpc.getnewaddress())
assert isinstance(dst_addr, CCoinConfidentialAddress)
say('I will claim my Elements-BTC to {}'.format(dst_addr))
elt_claim_tx = create_elt_spend_tx(
dst_addr,
elt_txid,
vout_n,
elt_contract,
die,
spend_key=bob_elt_spend_key,
contract_key=contract_key,
blinding_key=blinding_key,
blinding_factor=unblind_result.blinding_factor,
asset_blinding_factor=unblind_result.asset_blinding_factor)
# Cannot use VerifyScript for now,
# because it does not support CHECKSIGFROMSTACK yet
#
# VerifyScript(tx.vin[0].scriptSig,
# elt_contract_addr.to_scriptPubKey(),
# tx, 0, amount=amount)
say('Sending my spend-reveal transaction')
sr_txid = elt_rpc.sendrawtransaction(b2x(elt_claim_tx.serialize()))
wait_confirm(say, 'Elements', sr_txid, die, elt_rpc, num_confirms=2)
say('Got my Elements-BTC. Swap successful (at least for me :-)')
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')
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
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()
FEE_PER_VBYTE = 0.00025 * CoreCoinParams.COIN / 1000
while True:
def select_coins(self, address: ExternalAddress):
target_value = coins_to_satoshi(self.spend_amount, False)
return self.controller.select_coins(target_value, address,
self.priority_fee_selected)
def check_serialize_deserialize(self, tx, tx_bytes, tx_decoded):
self.assertEqual(tx_bytes, tx.serialize())
self.assertEqual(tx_bytes,
CTransaction.deserialize(tx.serialize()).serialize())
self.assertEqual(tx_bytes, tx.to_mutable().to_immutable().serialize())
self.assertEqual(tx_decoded['version'], tx.nVersion)
self.assertEqual(tx_decoded['locktime'], tx.nLockTime)
# we ignore withash field - we do not have ComputeWitnessHash() function
# as it is only relevant for blocks, not transactions
self.assertEqual(tx_decoded['hash'], b2lx(tx.GetHash()))
self.assertEqual(tx_decoded['txid'], b2lx(tx.GetTxid()))
for n, vout in enumerate(tx_decoded['vout']):
if 'amountcommitment' in vout:
self.assertEqual(x(vout['amountcommitment']),
tx.vout[n].nValue.commitment)
if 'assetcommitment' in vout:
self.assertEqual(x(vout['assetcommitment']),
tx.vout[n].nAsset.commitment)
if 'asset' in vout:
self.assertEqual(vout['asset'],
tx.vout[n].nAsset.to_asset().to_hex())
if 'scriptPubKey' in vout:
spk = vout['scriptPubKey']
self.assertEqual(x(spk['hex']), tx.vout[n].scriptPubKey)
if 'pegout_type' in spk:
self.assertEqual(spk['type'], 'nulldata')
self.assertTrue(tx.vout[n].scriptPubKey.is_pegout())
genesis_hash, pegout_scriptpubkey = tx.vout[
n].scriptPubKey.get_pegout_data()
if spk['pegout_type'] != 'nonstandard':
assert spk['pegout_type'] in ('pubkeyhash',
'scripthash')
addr = CCoinAddress.from_scriptPubKey(
pegout_scriptpubkey)
self.assertEqual(len(spk['pegout_addresses']), 1)
self.assertEqual(spk['pegout_addresses'][0], str(addr))
self.assertEqual(spk['pegout_hex'],
b2x(pegout_scriptpubkey))
self.assertEqual(spk['pegout_chain'], b2lx(genesis_hash))
if spk['type'] in ('pubkeyhash', 'scripthash'):
self.assertEqual(len(spk['addresses']), 1)
addr = CCoinAddress.from_scriptPubKey(
tx.vout[n].scriptPubKey)
self.assertEqual(spk['addresses'][0], str(addr))
elif spk['type'] == 'nulldata':
self.assertEqual(tx.vout[n].scriptPubKey, x(spk['hex']))
else:
self.assertEqual(spk['type'], 'fee')
self.assertEqual(len(tx.vout[n].scriptPubKey), 0)
if secp256k1_has_zkp:
if tx.wit.is_null():
rpinfo = None
else:
rpinfo = tx.wit.vtxoutwit[n].get_rangeproof_info()
if 'value-minimum' in vout:
self.assertIsNotNone(rpinfo)
self.assertEqual(vout['ct-exponent'], rpinfo.exp)
self.assertEqual(vout['ct-bits'], rpinfo.mantissa)
self.assertEqual(
coins_to_satoshi(vout['value-minimum'],
check_range=False), rpinfo.value_min)
self.assertEqual(
coins_to_satoshi(vout['value-maximum'],
check_range=False), rpinfo.value_max)
else:
self.assertTrue(rpinfo is None or rpinfo.exp == -1)
if rpinfo is None:
value = tx.vout[n].nValue.to_amount()
else:
value = rpinfo.value_min
self.assertEqual(coins_to_satoshi(vout['value']), value)
else:
warn_zkp_unavailable()
if 'value' in vout and tx.vout[n].nValue.is_explicit():
self.assertEqual(coins_to_satoshi(vout['value']),
tx.vout[n].nValue.to_amount())
for n, vin in enumerate(tx_decoded['vin']):
if 'scripSig' in vin:
self.assertEqual(
x(vin['scriptSig']['hex'], tx.vin[n].scriptSig))
if 'txid' in vin:
self.assertEqual(vin['txid'], b2lx(tx.vin[n].prevout.hash))
if 'vout' in vin:
self.assertEqual(vin['vout'], tx.vin[n].prevout.n)
if 'is_pegin' in vin:
self.assertEqual(vin['is_pegin'], tx.vin[n].is_pegin)
if vin['is_pegin'] is False:
if 'scriptWitness' in vin:
self.assertTrue(
tx.wit.vtxinwit[n].scriptWitness.is_null())
if 'pegin_witness' in vin:
self.assertTrue(
tx.wit.vtxinwit[n].pegin_witness.is_null())
else:
for stack_index, stack_item in enumerate(
vin['scriptWitness']):
self.assertTrue(
stack_item,
b2x(tx.wit.vtxinwit[n].scriptWitness.
stack[stack_index]))
for stack_index, stack_item in enumerate(
vin['pegin_witness']):
self.assertTrue(
stack_item,
b2x(tx.wit.vtxinwit[n].pegin_witness.
stack[stack_index]))
if 'sequence' in vin:
self.assertEqual(vin['sequence'], tx.vin[n].nSequence)
if 'coinbase' in vin:
self.assertTrue(tx.is_coinbase())
if 'issuance' in vin:
iss = vin['issuance']
self.assertEqual(
iss['assetBlindingNonce'],
tx.vin[n].assetIssuance.assetBlindingNonce.to_hex())
if 'asset' in iss:
if iss['isreissuance']:
self.assertTrue(not tx.vin[n].assetIssuance.
assetBlindingNonce.is_null())
self.assertEqual(
iss['assetEntropy'],
tx.vin[n].assetIssuance.assetEntropy.to_hex())
asset = calculate_asset(
tx.vin[n].assetIssuance.assetEntropy)
else:
entropy = generate_asset_entropy(
tx.vin[n].prevout,
tx.vin[n].assetIssuance.assetEntropy)
self.assertEqual(iss['assetEntropy'], entropy.to_hex())
asset = calculate_asset(entropy)
reiss_token = calculate_reissuance_token(
entropy,
tx.vin[n].assetIssuance.nAmount.is_commitment())
self.assertEqual(iss['token'], reiss_token.to_hex())
self.assertEqual(iss['asset'], asset.to_hex())
if 'assetamount' in iss:
self.assertEqual(
coins_to_satoshi(iss['assetamount']),
tx.vin[n].assetIssuance.nAmount.to_amount())
elif 'assetamountcommitment' in iss:
self.assertEqual(
iss['assetamountcommitment'],
b2x(tx.vin[n].assetIssuance.nAmount.commitment))
if 'tokenamount' in iss:
self.assertEqual(
coins_to_satoshi(iss['tokenamount']),
tx.vin[n].assetIssuance.nInflationKeys.to_amount())
elif 'tokenamountcommitment' in iss:
self.assertEqual(
iss['tokenamountcommitment'],
b2x(tx.vin[n].assetIssuance.nInflationKeys.commitment))
#
# 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('bff785da9f8169f49be92fa95e31f0890c385bfb1bd24d6b94d7900057c617ae')
vout = 0
# Create the txin structure, which includes the outpoint. The scriptSig
# defaults to being empty.
txin = CMutableTxIn(COutPoint(txid, vout))
# Create the txout. This time we create the scriptPubKey from a Bitcoin
# address.
txout = CMutableTxOut(
coins_to_satoshi(0.0005),
CBitcoinAddress('323uf9MgLaSn9T7vDaK1cGAZ2qpvYUuqSp').to_scriptPubKey())
# Create the unsigned transaction.
tx = CMutableTransaction([txin], [txout])
# Calculate the signature hash for that transaction. Note how the script we use
# is the redeemScript, not the scriptPubKey. That's because when the CHECKSIG
# operation happens EvalScript() will be evaluating the redeemScript, so the
# corresponding SignatureHash() function will use that same script when it
# replaces the scriptSig in the transaction being hashed with the script being
# executed.
sighash = SignatureHash(txin_redeemScript, tx, 0, SIGHASH_ALL)
# Now sign it. We have to append the type of signature we want to the end, in
# this case the usual SIGHASH_ALL.
def check_blind(self,
unblinded_tx,
unblinded_tx_raw,
blinded_tx,
blinded_tx_raw,
bundle,
blinding_derivation_key,
asset_commitments=()):
input_descriptors = []
for utxo in bundle['vin_utxo']:
amount = -1 if utxo['amount'] == -1 else coins_to_satoshi(
utxo['amount'])
input_descriptors.append(
BlindingInputDescriptor(
amount=amount,
asset=CAsset(lx(utxo['asset'])),
blinding_factor=Uint256(lx(utxo['blinder'])),
asset_blinding_factor=Uint256(lx(utxo['assetblinder']))))
num_to_blind = 0
output_pubkeys = []
for vout in unblinded_tx.vout:
if not vout.nNonce.is_null() and vout.nValue.is_explicit():
output_pubkeys.append(CPubKey(vout.nNonce.commitment))
num_to_blind += 1
else:
output_pubkeys.append(CPubKey())
tx_to_blind = unblinded_tx.to_mutable()
blind_issuance_asset_keys = []
blind_issuance_token_keys = []
for vin in blinded_tx.vin:
issuance = vin.assetIssuance
if not issuance.is_null():
issuance_blinding_script = CScript(
[OP_RETURN, vin.prevout.hash, vin.prevout.n])
blind_issuance_key = issuance_blinding_script.derive_blinding_key(
blinding_derivation_key)
if issuance.nAmount.is_commitment():
blind_issuance_asset_keys.append(blind_issuance_key)
num_to_blind += 1
else:
blind_issuance_asset_keys.append(None)
if issuance.nInflationKeys.is_commitment():
blind_issuance_token_keys.append(blind_issuance_key)
num_to_blind += 1
else:
blind_issuance_token_keys.append(None)
else:
blind_issuance_asset_keys.append(None)
blind_issuance_token_keys.append(None)
# Deterministic random was used when generating test transactions,
# to have reproducible results. We need to set the random seed
# to the same value that was used when test data was generated.
# (see note below on that supplying _rand_func parameter to blind()
# is intended only for testing code, not for production)
random.seed(bundle['rand_seed'])
def rand_func(n):
return bytes([random.randint(0, 255) for _ in range(n)])
# Auxiliary generators will be be non-empty only for the case
# when we are blinding different transaction templates that is
# then combined into one common transaction, that is done in
# test_split_blinding_multi_sign().
# In this case, you need to supply the asset commitments for
# all of the inputs of the final transaction, even if currently
# blinded transaction template does not contain these inputs.
blind_result = tx_to_blind.blind(
input_descriptors=input_descriptors,
output_pubkeys=output_pubkeys,
blind_issuance_asset_keys=blind_issuance_asset_keys,
blind_issuance_token_keys=blind_issuance_token_keys,
auxiliary_generators=asset_commitments,
# IMPORTANT NOTE:
# Specifying custom _rand_func is only required for testing.
# Here we use it to supply deterministically generated
# pseudo-random bytes, so that blinding results will match the test
# data that was generated using deterministically generated random
# bytes, with seed values that are saved in 'rand_seed' fields of
# test data bunldes.
#
# In normal code you do should NOT specify _rand_func:
# os.urandom will be used by default (os.urandom is suitable for cryptographic use)
_rand_func=rand_func)
self.assertFalse(blind_result.error)
if all(_k is None for _k in blind_issuance_asset_keys):
random.seed(bundle['rand_seed'])
tx_to_blind2 = unblinded_tx.to_mutable()
blind_result2 = tx_to_blind2.blind(
input_descriptors=input_descriptors,
output_pubkeys=output_pubkeys,
blind_issuance_asset_keys=blind_issuance_asset_keys,
blind_issuance_token_keys=blind_issuance_token_keys,
auxiliary_generators=asset_commitments,
_rand_func=rand_func)
self.assertFalse(blind_result2.error)
self.assertEqual(blind_result, blind_result2)
self.assertEqual(tx_to_blind.serialize(), tx_to_blind2.serialize())
self.assertEqual(blind_result.num_successfully_blinded, num_to_blind)
self.assertNotEqual(unblinded_tx_raw, tx_to_blind.serialize())
self.assertEqual(blinded_tx_raw, tx_to_blind.serialize())
