csv.spec.ts

import * as assert from 'assert';
import { PsbtInput } from 'bip174';
import ECPairFactory from 'ecpair';
import * as ecc from 'tiny-secp256k1';
import { before, describe, it } from 'mocha';
import * as bitcoin from 'bitcoinjs-lib';
import { regtestUtils } from './_regtest.js';
import { reverseBuffer } from 'bitcoinjs-lib/src/bufferutils';
import * as tools from 'uint8array-tools';

const ECPair = ECPairFactory(ecc);
const regtest = regtestUtils.network;
import bip68 from 'bip68';
import * as varuint from 'varuint-bitcoin';

function toOutputScript(address: string): Uint8Array {
  return bitcoin.address.toOutputScript(address, regtest);
}

function idToHash(txid: string): Uint8Array {
  return reverseBuffer(tools.fromHex(txid));
}

const alice = ECPair.fromWIF(
  'cScfkGjbzzoeewVWmU2hYPUHeVGJRDdFt7WhmrVVGkxpmPP8BHWe',
  regtest,
);
const bob = ECPair.fromWIF(
  'cMkopUXKWsEzAjfa1zApksGRwjVpJRB3831qM9W4gKZsLwjHXA9x',
  regtest,
);
const charles = ECPair.fromWIF(
  'cMkopUXKWsEzAjfa1zApksGRwjVpJRB3831qM9W4gKZsMSb4Ubnf',
  regtest,
);
const dave = ECPair.fromWIF(
  'cMkopUXKWsEzAjfa1zApksGRwjVpJRB3831qM9W4gKZsMwS4pqnx',
  regtest,
);

describe('bitcoinjs-lib (transactions w/ CSV)', () => {
  // force update MTP
  before(async () => {
    await regtestUtils.mine(11);
  });

  const hashType = bitcoin.Transaction.SIGHASH_ALL;

  interface KeyPair {
    publicKey: Uint8Array;
  }
  // IF MTP (from when confirmed) > seconds, _alice can redeem
  function csvCheckSigOutput(
    _alice: KeyPair,
    _bob: KeyPair,
    sequence: number,
  ): Uint8Array {
    return bitcoin.script.fromASM(
      `
      OP_IF
          ${tools.toHex(bitcoin.script.number.encode(sequence))}
          OP_CHECKSEQUENCEVERIFY
          OP_DROP
      OP_ELSE
          ${tools.toHex(_bob.publicKey)}
          OP_CHECKSIGVERIFY
      OP_ENDIF
      ${tools.toHex(_alice.publicKey)}
      OP_CHECKSIG
    `
        .trim()
        .replace(/\s+/g, ' '),
    );
  }

  // 2 of 3 multisig of _bob, _charles, _dave,
  // but after sequence1 time, _alice can allow the multisig to become 1 of 3.
  // but after sequence2 time, _alice can sign for the output all by themself.

  // Ref: https://github.com/bitcoinbook/bitcoinbook/blob/f8b883dcd4e3d1b9adf40fed59b7e898fbd9241f/ch07.asciidoc#complex-script-example

  // Note: bitcoinjs-lib will not offer specific support for problems with
  //       advanced script usages such as below. Use at your own risk.
  function complexCsvOutput(
    _alice: KeyPair,
    _bob: KeyPair,
    _charles: KeyPair,
    _dave: KeyPair,
    sequence1: number,
    sequence2: number,
  ): Uint8Array {
    return bitcoin.script.fromASM(
      `
      OP_IF
          OP_IF
              OP_2
          OP_ELSE
              ${tools.toHex(bitcoin.script.number.encode(sequence1))}
              OP_CHECKSEQUENCEVERIFY
              OP_DROP
              ${tools.toHex(_alice.publicKey)}
              OP_CHECKSIGVERIFY
              OP_1
          OP_ENDIF
          ${tools.toHex(_bob.publicKey)}
          ${tools.toHex(_charles.publicKey)}
          ${tools.toHex(_dave.publicKey)}
          OP_3
          OP_CHECKMULTISIG
      OP_ELSE
          ${tools.toHex(bitcoin.script.number.encode(sequence2))}
          OP_CHECKSEQUENCEVERIFY
          OP_DROP
          ${tools.toHex(_alice.publicKey)}
          OP_CHECKSIG
      OP_ENDIF
    `
        .trim()
        .replace(/\s+/g, ' '),
    );
  }

  // expiry will pass, {Alice's signature} OP_TRUE
  it(
    'can create (and broadcast via 3PBP) a Transaction where Alice can redeem ' +
      'the output after the expiry (in the future) (simple CHECKSEQUENCEVERIFY)',
    async () => {
      // 5 blocks from now
      const sequence = bip68.encode({ blocks: 5 });
      const p2sh = bitcoin.payments.p2sh({
        redeem: {
          output: csvCheckSigOutput(alice, bob, sequence),
        },
        network: regtest,
      });

      // fund the P2SH(CSV) address
      const unspent = await regtestUtils.faucet(p2sh.address!, 1e5);
      const utx = await regtestUtils.fetch(unspent.txId);
      // for non segwit inputs, you must pass the full transaction buffer
      const nonWitnessUtxo = Buffer.from(utx.txHex, 'hex');

      // This is an example of using the finalizeInput second parameter to
      // define how you finalize the inputs, allowing for any type of script.
      const tx = new bitcoin.Psbt({ network: regtest })
        .setVersion(2)
        .addInput({
          hash: unspent.txId,
          index: unspent.vout,
          sequence,
          redeemScript: p2sh.redeem!.output!,
          nonWitnessUtxo,
        })
        .addOutput({
          address: regtestUtils.RANDOM_ADDRESS,
          value: BigInt(7e4),
        })
        .signInput(0, alice)
        .finalizeInput(0, csvGetFinalScripts) // See csvGetFinalScripts below
        .extractTransaction();

      // TODO: test that it failures _prior_ to expiry, unfortunately, race conditions when run concurrently
      // ...
      // into the future!
      await regtestUtils.mine(10);

      await regtestUtils.broadcast(tx.toHex());

      await regtestUtils.verify({
        txId: tx.getId(),
        address: regtestUtils.RANDOM_ADDRESS,
        vout: 0,
        value: 7e4,
      });
    },
  ).timeout(8000);

  // expiry in the future, {Alice's signature} OP_TRUE
  it(
    'can create (but fail to broadcast via 3PBP) a Transaction where Alice ' +
      'attempts to redeem before the expiry (simple CHECKSEQUENCEVERIFY)',
    async () => {
      // two hours after confirmation
      const sequence = bip68.encode({ seconds: 7168 });
      const p2sh = bitcoin.payments.p2sh({
        network: regtest,
        redeem: {
          output: csvCheckSigOutput(alice, bob, sequence),
        },
      });

      // fund the P2SH(CSV) address
      const unspent = await regtestUtils.faucet(p2sh.address!, 2e4);

      const tx = new bitcoin.Transaction();
      tx.version = 2;
      tx.addInput(idToHash(unspent.txId), unspent.vout, sequence);
      tx.addOutput(toOutputScript(regtestUtils.RANDOM_ADDRESS), BigInt(1e4));

      // {Alice's signature} OP_TRUE
      const signatureHash = tx.hashForSignature(
        0,
        p2sh.redeem!.output!,
        hashType,
      );
      const redeemScriptSig = bitcoin.payments.p2sh({
        network: regtest,
        redeem: {
          network: regtest,
          output: p2sh.redeem!.output,
          input: bitcoin.script.compile([
            bitcoin.script.signature.encode(
              alice.sign(signatureHash),
              hashType,
            ),
            bitcoin.script.signature.encode(bob.sign(signatureHash), hashType),
            bitcoin.opcodes.OP_TRUE,
          ]),
        },
      }).input;
      tx.setInputScript(0, redeemScriptSig!);

      await regtestUtils.broadcast(tx.toHex()).catch(err => {
        assert.throws(() => {
          if (err) throw err;
        }, /Error: non-BIP68-final/);
      });
    },
  ).timeout(8000);

  // Check first combination of complex CSV, 2 of 3
  it(
    'can create (and broadcast via 3PBP) a Transaction where Bob and Charles ' +
      'can send (complex CHECKSEQUENCEVERIFY)',
    async () => {
      // 2 blocks from now
      const sequence1 = bip68.encode({ blocks: 2 });
      // 5 blocks from now
      const sequence2 = bip68.encode({ blocks: 5 });
      const p2sh = bitcoin.payments.p2sh({
        redeem: {
          output: complexCsvOutput(
            alice,
            bob,
            charles,
            dave,
            sequence1,
            sequence2,
          ),
        },
        network: regtest,
      });

      // fund the P2SH(CCSV) address
      const unspent = await regtestUtils.faucet(p2sh.address!, 1e5);

      const tx = new bitcoin.Transaction();
      tx.version = 2;
      tx.addInput(idToHash(unspent.txId), unspent.vout);
      tx.addOutput(toOutputScript(regtestUtils.RANDOM_ADDRESS), BigInt(7e4));

      // OP_0 {Bob sig} {Charles sig} OP_TRUE OP_TRUE
      const signatureHash = tx.hashForSignature(
        0,
        p2sh.redeem!.output!,
        hashType,
      );
      const redeemScriptSig = bitcoin.payments.p2sh({
        network: regtest,
        redeem: {
          network: regtest,
          output: p2sh.redeem!.output,
          input: bitcoin.script.compile([
            bitcoin.opcodes.OP_0,
            bitcoin.script.signature.encode(bob.sign(signatureHash), hashType),
            bitcoin.script.signature.encode(
              charles.sign(signatureHash),
              hashType,
            ),
            bitcoin.opcodes.OP_TRUE,
            bitcoin.opcodes.OP_TRUE,
          ]),
        },
      }).input;
      tx.setInputScript(0, redeemScriptSig!);

      await regtestUtils.broadcast(tx.toHex());

      await regtestUtils.verify({
        txId: tx.getId(),
        address: regtestUtils.RANDOM_ADDRESS,
        vout: 0,
        value: 7e4,
      });
    },
  ).timeout(8000);

  // Check first combination of complex CSV, mediator + 1 of 3 after 2 blocks
  it(
    'can create (and broadcast via 3PBP) a Transaction where Alice (mediator) ' +
      'and Bob can send after 2 blocks (complex CHECKSEQUENCEVERIFY)',
    async () => {
      // 2 blocks from now
      const sequence1 = bip68.encode({ blocks: 2 });
      // 5 blocks from now
      const sequence2 = bip68.encode({ blocks: 5 });
      const p2sh = bitcoin.payments.p2sh({
        redeem: {
          output: complexCsvOutput(
            alice,
            bob,
            charles,
            dave,
            sequence1,
            sequence2,
          ),
        },
        network: regtest,
      });

      // fund the P2SH(CCSV) address
      const unspent = await regtestUtils.faucet(p2sh.address!, 1e5);

      const tx = new bitcoin.Transaction();
      tx.version = 2;
      tx.addInput(idToHash(unspent.txId), unspent.vout, sequence1); // Set sequence1 for input
      tx.addOutput(toOutputScript(regtestUtils.RANDOM_ADDRESS), BigInt(7e4));

      // OP_0 {Bob sig} {Alice mediator sig} OP_FALSE OP_TRUE
      const signatureHash = tx.hashForSignature(
        0,
        p2sh.redeem!.output!,
        hashType,
      );
      const redeemScriptSig = bitcoin.payments.p2sh({
        network: regtest,
        redeem: {
          network: regtest,
          output: p2sh.redeem!.output,
          input: bitcoin.script.compile([
            bitcoin.opcodes.OP_0,
            bitcoin.script.signature.encode(bob.sign(signatureHash), hashType),
            bitcoin.script.signature.encode(
              alice.sign(signatureHash),
              hashType,
            ),
            bitcoin.opcodes.OP_0,
            bitcoin.opcodes.OP_TRUE,
          ]),
        },
      }).input;
      tx.setInputScript(0, redeemScriptSig!);

      // Wait 2 blocks
      await regtestUtils.mine(2);

      await regtestUtils.broadcast(tx.toHex());

      await regtestUtils.verify({
        txId: tx.getId(),
        address: regtestUtils.RANDOM_ADDRESS,
        vout: 0,
        value: 7e4,
      });
    },
  ).timeout(8000);

  // Check first combination of complex CSV, mediator after 5 blocks
  it(
    'can create (and broadcast via 3PBP) a Transaction where Alice (mediator) ' +
      'can send after 5 blocks (complex CHECKSEQUENCEVERIFY)',
    async () => {
      // 2 blocks from now
      const sequence1 = bip68.encode({ blocks: 2 });
      // 5 blocks from now
      const sequence2 = bip68.encode({ blocks: 5 });
      const p2sh = bitcoin.payments.p2sh({
        redeem: {
          output: complexCsvOutput(
            alice,
            bob,
            charles,
            dave,
            sequence1,
            sequence2,
          ),
        },
        network: regtest,
      });

      // fund the P2SH(CCSV) address
      const unspent = await regtestUtils.faucet(p2sh.address!, 1e5);

      const tx = new bitcoin.Transaction();
      tx.version = 2;
      tx.addInput(idToHash(unspent.txId), unspent.vout, sequence2); // Set sequence2 for input
      tx.addOutput(toOutputScript(regtestUtils.RANDOM_ADDRESS), BigInt(7e4));

      // {Alice mediator sig} OP_FALSE
      const signatureHash = tx.hashForSignature(
        0,
        p2sh.redeem!.output!,
        hashType,
      );
      const redeemScriptSig = bitcoin.payments.p2sh({
        network: regtest,
        redeem: {
          network: regtest,
          output: p2sh.redeem!.output,
          input: bitcoin.script.compile([
            bitcoin.script.signature.encode(
              alice.sign(signatureHash),
              hashType,
            ),
            bitcoin.opcodes.OP_0,
          ]),
        },
      }).input;
      tx.setInputScript(0, redeemScriptSig!);

      // Wait 5 blocks
      await regtestUtils.mine(5);

      await regtestUtils.broadcast(tx.toHex());

      await regtestUtils.verify({
        txId: tx.getId(),
        address: regtestUtils.RANDOM_ADDRESS,
        vout: 0,
        value: 7e4,
      });
    },
  ).timeout(8000);
});

// This function is used to finalize a CSV transaction using PSBT.
// See first test above.
function csvGetFinalScripts(
  inputIndex: number,
  input: PsbtInput,
  script: Uint8Array,
  isSegwit: boolean,
  isP2SH: boolean,
  isP2WSH: boolean,
): {
  finalScriptSig: Uint8Array | undefined;
  finalScriptWitness: Uint8Array | undefined;
} {
  // Step 1: Check to make sure the meaningful script matches what you expect.
  const decompiled = bitcoin.script.decompile(script);
  // Checking if first OP is OP_IF... should do better check in production!
  // You may even want to check the public keys in the script against a
  // whitelist depending on the circumstances!!!
  // You also want to check the contents of the input to see if you have enough
  // info to actually construct the scriptSig and Witnesses.
  if (!decompiled || decompiled[0] !== bitcoin.opcodes.OP_IF) {
    throw new Error(`Can not finalize input #${inputIndex}`);
  }

  // Step 2: Create final scripts
  let payment: bitcoin.Payment = {
    network: regtest,
    output: script,
    // This logic should be more strict and make sure the pubkeys in the
    // meaningful script are the ones signing in the PSBT etc.
    input: bitcoin.script.compile([
      input.partialSig![0].signature,
      bitcoin.opcodes.OP_TRUE,
    ]),
  };
  if (isP2WSH && isSegwit)
    payment = bitcoin.payments.p2wsh({
      network: regtest,
      redeem: payment,
    });
  if (isP2SH)
    payment = bitcoin.payments.p2sh({
      network: regtest,
      redeem: payment,
    });

  function witnessStackToScriptWitness(witness: Uint8Array[]): Uint8Array {
    let buffer = new Uint8Array(0);

    function writeSlice(slice: Uint8Array): void {
      buffer = Buffer.concat([buffer, slice]);
    }

    function writeVarInt(i: number): void {
      const currentLen = buffer.length;
      const varintLen = varuint.encodingLength(i);

      buffer = Buffer.concat([buffer, Buffer.allocUnsafe(varintLen)]);
      varuint.encode(i, buffer, currentLen);
    }

    function writeVarSlice(slice: Uint8Array): void {
      writeVarInt(slice.length);
      writeSlice(slice);
    }

    function writeVector(vector: Uint8Array[]): void {
      writeVarInt(vector.length);
      vector.forEach(writeVarSlice);
    }

    writeVector(witness);

    return buffer;
  }

  return {
    finalScriptSig: payment.input,
    finalScriptWitness:
      payment.witness && payment.witness.length > 0
        ? witnessStackToScriptWitness(payment.witness)
        : undefined,
  };
}