computational_puzzle_SHA1_collision_p2sh.js

const bitcoin = require('bitcoinjs-lib')
const { alice } = require('./wallets.json')
const network = bitcoin.networks.regtest

// Redeem script and P2SH address
const redeemScript = bitcoin.script.compile([
  bitcoin.opcodes.OP_2DUP,
  bitcoin.opcodes.OP_EQUAL,
  bitcoin.opcodes.OP_NOT,
  bitcoin.opcodes.OP_VERIFY,
  bitcoin.opcodes.OP_SHA1,
  bitcoin.opcodes.OP_SWAP,
  bitcoin.opcodes.OP_SHA1,
  bitcoin.opcodes.OP_EQUAL])

console.log('Redeem script:')
console.log(redeemScript.toString('hex'))

const p2sh = bitcoin.payments.p2sh({redeem: {output: redeemScript, network}, network})


// Recipient
const keyPairAlice1 = bitcoin.ECPair.fromWIF(alice[1].wif, network)
const p2wpkhAlice1 = bitcoin.payments.p2wpkh({pubkey: keyPairAlice1.publicKey, network})


// Build transaction
const txb = new bitcoin.TransactionBuilder(network)

txb.addInput('TX_ID', TX_VOUT)
txb.addOutput(p2wpkhAlice1.address, 999e5)

const tx = txb.buildIncomplete()

const value_1 = '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'
const value_2 = '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'

const InputScriptP2SH = bitcoin.script.compile([
  Buffer.from(value_1, 'hex'),
  Buffer.from(value_2, 'hex'),
  p2sh.redeem.output
])
tx.setInputScript(0, InputScriptP2SH)

console.log('Transaction hexadecimal:')
console.log(tx.toHex())