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 mktx(ins, outs, version=1, locktime=0): """ Given a list of input tuples (txid(bytes), n(int)), and a list of outputs which are dicts with keys "address" (value should be *str* not CCoinAddress) ( or alternately "script" (for nonstandard outputs, value should be CScript)), "value" (value should be integer satoshis), outputs a CMutableTransaction object. Tx version and locktime are optionally set, for non-default locktimes, inputs are given nSequence as per below comment. """ vin = [] vout = [] # This does NOT trigger rbf and mimics Core's standard behaviour as of # Jan 2019. # Tx creators wishing to use rbf will need to set it explicitly outside # of this function. if locktime != 0: sequence = 0xffffffff - 1 else: sequence = 0xffffffff for i in ins: outpoint = CMutableOutPoint((i[0][::-1]), i[1]) inp = CMutableTxIn(prevout=outpoint, nSequence=sequence) vin.append(inp) for o in outs: if "script" in o: sPK = o["script"] else: # note the to_scriptPubKey method is only available for standard # address types sPK = CCoinAddress(o["address"]).to_scriptPubKey() out = CMutableTxOut(o["value"], sPK) vout.append(out) return CMutableTransaction(vin, vout, nLockTime=locktime, nVersion=version)
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 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 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 test_is_coinbase(self): tx = CMutableTransaction() self.assertFalse(tx.is_coinbase()) tx.vin.append(CMutableTxIn()) # IsCoinBase() in reference client doesn't check if vout is empty self.assertTrue(tx.is_coinbase()) tx.vin[0].prevout.n = 0 self.assertFalse(tx.is_coinbase()) tx.vin[0] = CTxIn() tx.vin.append(CTxIn()) self.assertFalse(tx.is_coinbase())
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
# 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()) # 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]) # Verify the signature worked. This calls EvalScript() and actually executes # the opcodes in the scripts to see if everything worked out. If it doesn't an # exception will be raised. VerifyScript(txin.scriptSig, txin_scriptPubKey, tx, 0)
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 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_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 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