bitcore-payment-codes-cash/lib/notificationOut.js

Payment Codes (BIP47) support for Bitcoin Cash

'use strict';

var bitcore = require('bitcore-lib-cash');
var _ = bitcore.deps._;
var $ = bitcore.util.preconditions;
var Transaction = bitcore.Transaction;
var BufferUtil = bitcore.util.buffer;
var PublicKey = bitcore.PublicKey;
var PrivateKey = bitcore.PrivateKey;
var Script = bitcore.Script;
var Point = bitcore.crypto.Point;
var PC = require ('../');

/* Creates a outgoint notification: Alice (sender) want to pay Bob (recipient)
 * this class is for Alice to create a notification to Bob, using his scanner 
 * PaymentCode, her own payment code, the UTXO she is planning to use for the
 * notification's TX source,  
 *
 * Seehttps://github.com/justusranvier/bips/blob/760f19c346fe9f12e8e5cce0c809369e2a6f7543/bip-0047.mediawiki#notification-transaction
 * */
function NotificationOut(senderPc, recipientPc, utxoPrivateKey, outpoint) {
  $.checkArgument(utxoPrivateKey, "utxoPrivateKey key must be supplied");
  outpoint  = outpoint || 0;
  var self = this;

  var privateKey = new PrivateKey(utxoPrivateKey);
  var ourPc = new PC.PaymentCode(senderPc);
  var hisPc = new PC.PaymentCode(recipientPc);

  var publicKeys = [];
  var secrets = [];
  var outputs = [];


  // i. Alice selects the private key corresponding to the designated pubkey:
  var a = privateKey.bn;

  _.each(hisPc.xPubKeys, function(xpub) {
    var pubKey =xpub.derive('m/0').publicKey;


    // ii. Alice selects the public key associated with Bob's notification address:
    var B = pubKey.point;

    // iii. Alice calculates a secret point:
    var secret = new PC.Secret(B.mul(a));

    // iv. Alice calculates a 64 byte blinding factor:
    var bf = new PC.BlindingFactor(secret, outpoint);

    var output = new Buffer(ourPc.buffer);
    bf.apply(output);
    secrets.push(secret);
    outputs.push(output);
  });

  this.secrets = secrets;
  this.outputs = outputs
  this.utxoPublicKey = utxoPrivateKey.publicKey;
};

NotificationOut.prototype.getScriptPubKey = function() {
   return Script.buildPublicKeyHashOut(this.utxoPublicKey);
};

module.exports = NotificationOut;