1  #!/usr/bin/env python3
  2  # Copyright (c) 2021-2022 The Bitcoin Core developers
  3  # Distributed under the MIT software license, see the accompanying
  4  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  5  """Test a basic M-of-N multisig setup between multiple people using descriptor wallets and PSBTs, as well as a signing flow.
  6  
  7  This is meant to be documentation as much as functional tests, so it is kept as simple and readable as possible.
  8  """
  9  
 10  from test_framework.test_framework import BitcoinTestFramework
 11  from test_framework.util import (
 12      assert_approx,
 13      assert_equal,
 14  )
 15  
 16  
 17  class WalletMultisigDescriptorPSBTTest(BitcoinTestFramework):
 18      def set_test_params(self):
 19          self.num_nodes = 3
 20          self.setup_clean_chain = True
 21          self.wallet_names = []
 22          self.extra_args = [["-keypool=100"]] * self.num_nodes
 23  
 24      def skip_test_if_missing_module(self):
 25          self.skip_if_no_wallet()
 26  
 27      @staticmethod
 28      def _get_xpub(wallet, internal):
 29          """Extract the wallet's xpubs using `listdescriptors` and pick the one from the `pkh` descriptor since it's least likely to be accidentally reused (legacy addresses)."""
 30          pkh_descriptor = next(filter(lambda d: d["desc"].startswith("pkh(") and d["internal"] == internal, wallet.listdescriptors()["descriptors"]))
 31          # Keep all key origin information (master key fingerprint and all derivation steps) for proper support of hardware devices
 32          # See section 'Key origin identification' in 'doc/descriptors.md' for more details...
 33          return pkh_descriptor["desc"].split("pkh(")[1].split(")")[0]
 34  
 35      @staticmethod
 36      def _check_psbt(psbt, to, value, multisig):
 37          """Helper function for any of the N participants to check the psbt with decodepsbt and verify it is OK before signing."""
 38          tx = multisig.decodepsbt(psbt)["tx"]
 39          amount = 0
 40          for vout in tx["vout"]:
 41              address = vout["scriptPubKey"]["address"]
 42              assert_equal(multisig.getaddressinfo(address)["ischange"], address != to)
 43              if address == to:
 44                  amount += vout["value"]
 45          assert_approx(amount, float(value), vspan=0.001)
 46  
 47      def participants_create_multisigs(self, external_xpubs, internal_xpubs):
 48          """The multisig is created by importing the following descriptors. The resulting wallet is watch-only and every participant can do this."""
 49          for i, node in enumerate(self.nodes):
 50              node.createwallet(wallet_name=f"{self.name}_{i}", blank=True, descriptors=True, disable_private_keys=True)
 51              multisig = node.get_wallet_rpc(f"{self.name}_{i}")
 52              external = multisig.getdescriptorinfo(f"wsh(sortedmulti({self.M},{','.join(external_xpubs)}))")
 53              internal = multisig.getdescriptorinfo(f"wsh(sortedmulti({self.M},{','.join(internal_xpubs)}))")
 54              result = multisig.importdescriptors([
 55                  {  # receiving addresses (internal: False)
 56                      "desc": external["descriptor"],
 57                      "active": True,
 58                      "internal": False,
 59                      "timestamp": "now",
 60                  },
 61                  {  # change addresses (internal: True)
 62                      "desc": internal["descriptor"],
 63                      "active": True,
 64                      "internal": True,
 65                      "timestamp": "now",
 66                  },
 67              ])
 68              assert all(r["success"] for r in result)
 69              yield multisig
 70  
 71      def run_test(self):
 72          self.M = 2
 73          self.N = self.num_nodes
 74          self.name = f"{self.M}_of_{self.N}_multisig"
 75          self.log.info(f"Testing {self.name}...")
 76  
 77          participants = {
 78              # Every participant generates an xpub. The most straightforward way is to create a new descriptor wallet.
 79              # This wallet will be the participant's `signer` for the resulting multisig. Avoid reusing this wallet for any other purpose (for privacy reasons).
 80              "signers": [node.get_wallet_rpc(node.createwallet(wallet_name=f"participant_{self.nodes.index(node)}", descriptors=True)["name"]) for node in self.nodes],
 81              # After participants generate and exchange their xpubs they will each create their own watch-only multisig.
 82              # Note: these multisigs are all the same, this just highlights that each participant can independently verify everything on their own node.
 83              "multisigs": []
 84          }
 85  
 86          self.log.info("Generate and exchange xpubs...")
 87          external_xpubs, internal_xpubs = [[self._get_xpub(signer, internal) for signer in participants["signers"]] for internal in [False, True]]
 88  
 89          self.log.info("Every participant imports the following descriptors to create the watch-only multisig...")
 90          participants["multisigs"] = list(self.participants_create_multisigs(external_xpubs, internal_xpubs))
 91  
 92          self.log.info("Check that every participant's multisig generates the same addresses...")
 93          for _ in range(10):  # we check that the first 10 generated addresses are the same for all participant's multisigs
 94              receive_addresses = [multisig.getnewaddress() for multisig in participants["multisigs"]]
 95              assert all(address == receive_addresses[0] for address in receive_addresses)
 96              change_addresses = [multisig.getrawchangeaddress() for multisig in participants["multisigs"]]
 97              assert all(address == change_addresses[0] for address in change_addresses)
 98  
 99          self.log.info("Get a mature utxo to send to the multisig...")
100          coordinator_wallet = participants["signers"][0]
101          self.generatetoaddress(self.nodes[0], 101, coordinator_wallet.getnewaddress())
102  
103          deposit_amount = 6.15
104          multisig_receiving_address = participants["multisigs"][0].getnewaddress()
105          self.log.info("Send funds to the resulting multisig receiving address...")
106          coordinator_wallet.sendtoaddress(multisig_receiving_address, deposit_amount)
107          self.generate(self.nodes[0], 1)
108          for participant in participants["multisigs"]:
109              assert_approx(participant.getbalance(), deposit_amount, vspan=0.001)
110  
111          self.log.info("Send a transaction from the multisig!")
112          to = participants["signers"][self.N - 1].getnewaddress()
113          value = 1
114          self.log.info("First, make a sending transaction, created using `walletcreatefundedpsbt` (anyone can initiate this)...")
115          psbt = participants["multisigs"][0].walletcreatefundedpsbt(inputs=[], outputs={to: value}, feeRate=0.00010)
116  
117          psbts = []
118          self.log.info("Now at least M users check the psbt with decodepsbt and (if OK) signs it with walletprocesspsbt...")
119          for m in range(self.M):
120              signers_multisig = participants["multisigs"][m]
121              self._check_psbt(psbt["psbt"], to, value, signers_multisig)
122              signing_wallet = participants["signers"][m]
123              partially_signed_psbt = signing_wallet.walletprocesspsbt(psbt["psbt"])
124              psbts.append(partially_signed_psbt["psbt"])
125  
126          self.log.info("Finally, collect the signed PSBTs with combinepsbt, finalizepsbt, then broadcast the resulting transaction...")
127          combined = coordinator_wallet.combinepsbt(psbts)
128          finalized = coordinator_wallet.finalizepsbt(combined)
129          coordinator_wallet.sendrawtransaction(finalized["hex"])
130  
131          self.log.info("Check that balances are correct after the transaction has been included in a block.")
132          self.generate(self.nodes[0], 1)
133          assert_approx(participants["multisigs"][0].getbalance(), deposit_amount - value, vspan=0.001)
134          assert_equal(participants["signers"][self.N - 1].getbalance(), value)
135  
136          self.log.info("Send another transaction from the multisig, this time with a daisy chained signing flow (one after another in series)!")
137          psbt = participants["multisigs"][0].walletcreatefundedpsbt(inputs=[], outputs={to: value}, feeRate=0.00010)
138          for m in range(self.M):
139              signers_multisig = participants["multisigs"][m]
140              self._check_psbt(psbt["psbt"], to, value, signers_multisig)
141              signing_wallet = participants["signers"][m]
142              psbt = signing_wallet.walletprocesspsbt(psbt["psbt"])
143              assert_equal(psbt["complete"], m == self.M - 1)
144          coordinator_wallet.sendrawtransaction(psbt["hex"])
145  
146          self.log.info("Check that balances are correct after the transaction has been included in a block.")
147          self.generate(self.nodes[0], 1)
148          assert_approx(participants["multisigs"][0].getbalance(), deposit_amount - (value * 2), vspan=0.001)
149          assert_equal(participants["signers"][self.N - 1].getbalance(), value * 2)
150  
151  
152  if __name__ == "__main__":
153      WalletMultisigDescriptorPSBTTest(__file__).main()