scriptutil.js

'use strict';

var bcoin = require('bcoin');
var bn = bcoin.bn;
var constants = bcoin.constants;
var utils = require('bcoin/lib/utils/utils');
var crypto = require('bcoin/lib/crypto/crypto');
var assert = utils.assert;
var opcodes = constants.opcodes;
var hashType = constants.hashType;
var util = exports;

util.toWitnessScripthash = function(redeem) {
  return bcoin.script.fromProgram(0, redeem.sha256());
};

util.toMultisig = function(k1, k2) {
  var script = new bcoin.script();
  var k;

  // Note: It looks like lnd orders these in reverse.
  if (utils.cmp(k1, k2) < 0) {
    k = k1;
    k1 = k2;
    k2 = k;
  }

  script.push(opcodes.OP_2);
  script.push(k1);
  script.push(k2);
  script.push(opcodes.OP_2);
  script.push(opcodes.OP_CHECKMULTISIG);
  script.compile();

  return script;
};

util.fundingRedeem = function(k1, k2, value) {
  var redeem = util.toMultisig(k1, k2);
  var output = new bcoin.output();

  output.script = util.toWitnessScripthash(redeem);
  output.value = value;

  assert(value > 0);

  return {
    redeem: redeem,
    output: output
  };
};

util.spendMultisig = function(redeem, k1, s1, k2, s2) {
  var witness = new bcoin.witness();

  witness.push(new Buffer(0));

  // Note: It looks like lnd orders these in reverse.
  if (utils.cmp(k1, k2) < 0) {
    witness.push(s2);
    witness.push(s1);
  } else {
    witness.push(s1);
    witness.push(s2);
  }

  witness.push(redeem.toRaw());
  witness.compile();

  return witness;
};

util.findOutput = function(tx, script) {
  var i, output;

  for (i = 0; i < tx.outputs.length; i++) {
    output = tx.outputs[i];
    if (utils.equal(output.script.toRaw(), script.toRaw()))
      return i;
  }

  return -1;
};

util.createSenderHTLC = function(absTimeout, relTimeout, senderKey, recKey, revHash, payHash) {
  var script = new bcoin.script();
  script.push(opcodes.OP_IF);
  script.push(opcodes.OP_IF);
  script.push(revHash);
  script.push(opcodes.OP_ELSE);
  script.push(opcodes.OP_SIZE);
  script.push(new bn(32));
  script.push(opcodes.OP_EQUALVERIFY);
  script.push(payHash);
  script.push(opcodes.OP_ENDIF);
  script.push(opcodes.OP_SWAP);
  script.push(opcodes.OP_SHA256);
  script.push(opcodes.OP_EQUALVERIFY);
  script.push(recKey);
  script.push(opcodes.OP_CHECKSIG);
  script.push(opcodes.OP_ELSE);
  script.push(new bn(absTimeout));
  script.push(opcodes.OP_CHECKLOCKTIMEVERIFY);
  script.push(new bn(relTimeout));
  script.push(opcodes.OP_CHECKSEQUENCEVERIFY);
  script.push(opcodes.OP_2DROP);
  script.push(senderKey);
  script.push(opcodes.OP_CHECKSIG);
  script.push(opcodes.OP_ENDIF);
  script.compile();
  return script;
};

util.senderSpendRedeem = function(commitScript, recKey, sweep, payImage) {
  var sig = sweep.signature(0, commitScript, recKey, hashType.ALL, 1);
  var witness = new bcoin.witness();
  witness.push(sig);
  witness.push(payImage);
  witness.push(new bn(0));
  witness.push(new bn(1));
  witness.push(commitScript.toRaw());
  witness.compile();
  return witness;
};

util.senderSpendRevoke = function(commitScript, recKey, sweep, revImage) {
  var sig = sweep.signature(0, commitScript, recKey, hashType.ALL, 1);
  var witness = new bcoin.witness();
  witness.push(sig);
  witness.push(revImage);
  witness.push(new bn(1));
  witness.push(new bn(1));
  witness.push(commitScript.toRaw());
  witness.compile();
  return witness;
};

util.senderSpendTimeout = function(commitScript, senderKey, sweep, absTimeout, relTime) {
  var sig, witness;

  sweep.setSequence(0, relTime);
  sweep.setLocktime(absTimeout);

  sig = sweep.signature(0, commitScript, senderKey, hashType.ALL, 1);

  witness = new bcoin.witness();
  witness.push(sig);
  witness.push(new bn(0));
  witness.push(commitScript.toRaw());
  witness.compile();

  return witness;
};

util.createReceiverHTLC = function(absTimeout, relTimeout, senderKey, recKey, revHash, payHash) {
  var script = new bcoin.script();
  script.push(opcodes.OP_IF);
  script.push(opcodes.OP_SIZE);
  script.push(new bn(32));
  script.push(opcodes.OP_EQUALVERIFY);
  script.push(opcodes.OP_SHA256);
  script.push(payHash);
  script.push(opcodes.OP_EQUALVERIFY);
  script.push(new bn(relTimeout));
  script.push(opcodes.OP_CHECKSEQUENCEVERIFY);
  script.push(opcodes.OP_DROP);
  script.push(recKey);
  script.push(opcodes.OP_CHECKSIG);
  script.push(opcodes.OP_ELSE);
  script.push(opcodes.OP_IF);
  script.push(opcodes.OP_SHA256);
  script.push(revHash);
  script.push(opcodes.OP_EQUALVERIFY);
  script.push(opcodes.OP_ELSE);
  script.push(new bn(absTimeout));
  script.push(opcodes.OP_CHECKLOCKTIMEVERIFY);
  script.push(opcodes.OP_DROP);
  script.push(opcodes.OP_ENDIF);
  script.push(senderKey);
  script.push(opcodes.OP_CHECKSIG);
  script.push(opcodes.OP_ENDIF);
  script.compile();
  return script;
};

util.recSpendRedeem = function(commitScript, recKey, sweep, payImage, relTime) {
  var sig, witness;

  sweep.setSequence(0, relTime);

  sig = sweep.signature(0, commitScript, recKey, hashType.ALL, 1);

  witness = new bcoin.witness();
  witness.push(sig);
  witness.push(payImage);
  witness.push(new bn(1));
  witness.push(commitScript.toRaw());
  witness.compile();

  return witness;
};

util.recSpendRevoke = function(commitScript, senderKey, sweep, revImage) {
  var sig = sweep.signature(0, commitScript, senderKey, hashType.ALL, 1);
  var witness = new bcoin.witness();
  witness.push(sig);
  witness.push(revImage);
  witness.push(new bn(1));
  witness.push(new bn(0));
  witness.push(commitScript.toRaw());
  witness.compile();
  return witness;
};

util.recSpendTimeout = function(commitScript, senderKey, sweep, absTimeout) {
  var sig, witness;

  sweep.setLocktime(absTimeout);

  sig = sweep.signature(0, commitScript, senderKey, hashType.ALL, 1);

  witness = new bcoin.witness();
  witness.push(sig);
  witness.push(new bn(0));
  witness.push(new bn(0));
  witness.push(commitScript.toRaw());
  witness.compile();

  return witness;
};

util.commitSelf = function commitSelf(csvTime, selfKey, revKey) {
  var script = new bcoin.script();
  script.push(opcodes.OP_IF);
  script.push(revKey);
  script.push(opcodes.OP_CHECKSIG);
  script.push(opcodes.OP_ELSE);
  script.push(selfKey);
  script.push(opcodes.OP_CHECKSIGVERIFY);
  script.push(new bn(csvTime));
  script.push(opcodes.OP_CHECKSEQUENCEVERIFY);
  script.push(opcodes.OP_ENDIF);
  script.compile();
  return script;
};

util.commitUnencumbered = function commitUnencumbered(key) {
  return bcoin.script.fromProgram(0, crypto.hash160(key));
};

util.commitSpendTimeout = function commitSpendTimeout(commitScript, blockTimeout, selfKey, sweep) {
  var sig, witness;

  sweep.setSequence(0, blockTimeout);

  sig = sweep.signature(0, commitScript, selfKey, hashType.ALL, 1);
  witness = new bcoin.witness();
  witness.push(sig);
  witness.push(new bn(0));
  witness.push(commitScript.toRaw());
  witness.compile();

  return witness;
};

util.commitSpendRevoke = function commitSpendRevoke(commitScript, revPriv, sweep) {
  var sig = sweep.signature(0, commitScript, revPriv, hashType.ALL, 1);
  var witness = new bcoin.witness();
  witness.push(sig);
  witness.push(new bn(1));
  witness.push(commitScript.toRaw());
  witness.compile();
  return witness;
};

util.commitSpendNoDelay = function commitSpendNoDelay(commitScript, commitPriv, sweep) {
  var pkh = bcoin.script.fromPubkeyhash(commitScript.get(1));
  var sig = sweep.signature(0, pkh, commitPriv, hashType.ALL, 1);
  var witness = new bcoin.witness();
  witness.push(sig);
  witness.push(bcoin.ec.publicKeyCreate(commitPriv, true));
  witness.compile();
  return witness;
};

util.deriveRevPub = function(commitPub, revImage) {
  return bcoin.ec.publicKeyTweakAdd(commitPub, revImage, true);
};

util.deriveRevPriv = function(commitPriv, revImage) {
  return bcoin.ec.privateKeyTweakAdd(commitPriv, revImage);
};

util.deriveElkremRoot = function(localKey, remoteKey) {
  var secret = localKey; // private
  var salt = remoteKey; // public
  var info = new Buffer('elkrem', 'ascii');
  var prk = crypto.hkdfExtract(secret, salt, 'sha256');
  var root = crypto.hkdfExpand(prk, info, 32, 'sha256');
  return root;
};

util.createCommitTX = function(
  fundingOutput, selfKey, theirKey, revKey,
  csvTimeout, valueToSelf, valueToThem
) {
  var ourRedeem = util.commitSelf(csvTimeout, selfKey, revKey);
  var payToUs = util.toWitnessScripthash(ourRedeem);
  var payToThem = util.commitUnencumbered(theirKey);
  var tx = new bcoin.mtx();
  var output;

  tx.version = 2;
  tx.addInput(fundingOutput);

  if (valueToSelf > 0) {
    output = new bcoin.output();
    output.value = valueToSelf;
    output.script = payToUs;
    tx.addOutput(output);
  }

  if (valueToThem > 0) {
    output = new bcoin.output();
    output.value = valueToThem;
    output.script = payToThem;
    tx.addOutput(output);
  }

  return tx;
};

util.createCooperativeClose = function createCooperativeClose(
  fundingInput, ourBalance, theirBalance,
  ourDeliveryScript, theirDeliveryScript,
  initiator
) {
  var tx = new bcoin.mtx();
  var output;

  tx.addInput(fundingInput);

  if (initiator)
    ourBalance -= 5000;
  else
    theirBalance -= 5000;

  if (ourBalance > 0) {
    output = new bcoin.output();
    output.script = ourDeliveryScript;
    output.value = ourBalance;
    tx.addOutput(output);
  }

  if (theirBalance > 0) {
    output = new bcoin.output();
    output.script = theirDeliveryScript;
    output.value = theirBalance;
    tx.addOutput(output);
  }

  tx.sortMembers();

  return tx;
};