know-js/lib/ecpair.js

JavaScript library for sending Know transactions from the client or server

var base58check = require('bs58check')
var bcrypto = require('./crypto')
var ecdsa = require('./ecdsa')
var ECSignature = require('./ecsignature')
var randomBytes = require('randombytes')
var typeforce = require('typeforce')
var types = require('./types')
var wif = require('wif')

var NETWORKS = require('./networks')
var BigInteger = require('bigi')

var ecurve = require('ecurve')
var secp256k1 = ecurve.getCurveByName('secp256k1')

var secp256k1native = require('secp256k1')

/**
 * Provide either `d` or `Q` but not both.
 *
 * @constructor
 * @param {BigInteger} [d] Private key.
 * @param {Point} [Q] Public key.
 * @param {object} [options]
 * @param {boolean} [options.compressed=true]
 * @param {Network} [options.network=networks.know]
 */
function ECPair (d, Q, options) {
  if (options) {
    typeforce({
      compressed: types.maybe(types.Boolean),
      network: types.maybe(types.Network)
    }, options)
  }

  options = options || {}

  if (d) {
    if (d.signum() <= 0) throw new Error('Private key must be greater than 0')
    if (d.compareTo(secp256k1.n) >= 0) throw new Error('Private key must be less than the curve order')
    if (Q) throw new TypeError('Unexpected publicKey parameter')

    this.d = d
  } else {
    typeforce(types.ECPoint, Q)

    this.__Q = Q
  }

  /** @type {boolean} */ this.compressed = options.compressed === undefined ? true : options.compressed
  /** @type {Network} */ this.network = options.network || NETWORKS.know
}

Object.defineProperty(ECPair.prototype, 'Q', {
  get: function () {
    if (!this.__Q && this.d) {
      this.__Q = secp256k1.G.multiply(this.d)
    }

    return this.__Q
  }
})

/**
 * @param {Buffer} buffer
 * @param {Network} [network=networks.know]
 * @returns {ECPair}
 */
ECPair.fromPublicKeyBuffer = function (buffer, network) {
  var Q = ecurve.Point.decodeFrom(secp256k1, buffer)

  return new ECPair(null, Q, {
    compressed: Q.compressed,
    network: network
  })
}

/**
 * @param {string} string
 * @param {Network[]|Network} network
 * @returns {ECPair}
 */
ECPair.fromWIF = function (string, network) {
  var decoded = wif.decode(string)
  var version = decoded.version

  // [network, ...]
  if (types.Array(network)) {
    network = network.filter(function (network) {
      return version === network.wif
    }).pop()

    if (!network) throw new Error('Unknown network version')

  // network
  } else {
    network = network || NETWORKS.know

    if (version !== network.wif) throw new Error('Invalid network version')
  }

  var d = BigInteger.fromBuffer(decoded.privateKey)

  return new ECPair(d, null, {
    compressed: decoded.compressed,
    network: network
  })
}

/**
 * @param {object} [options]
 * @param {function} [options.rng]
 * @param {boolean} [options.compressed=true]
 * @param {Network} [options.network=networks.know]
 */
ECPair.makeRandom = function (options) {
  options = options || {}

  var rng = options.rng || randomBytes

  var d
  do {
    var buffer = rng(32)
    typeforce(types.Buffer256bit, buffer)

    d = BigInteger.fromBuffer(buffer)
  } while (d.signum() <= 0 || d.compareTo(secp256k1.n) >= 0)

  return new ECPair(d, null, options)
}

/**
 * @param {string} seed
 * @param {object} [options]
 * @param {boolean} [options.compressed=true]
 * @param {Network} [options.network=networks.know]
 * @returns {ECPair}
 */
ECPair.fromSeed = function(seed, options) {
  var hash = bcrypto.sha256(new Buffer(seed,"utf-8"))
  var d = BigInteger.fromBuffer(hash)
  if(d.signum() <= 0 || d.compareTo(secp256k1.n) >= 0){
    throw new Error("seed cannot resolve to a compatible private key")
  }
  else{
    return new ECPair(d, null, options)
  }
}

/**
 * @returns {string}
 */
ECPair.prototype.getAddress = function () {
  var payload = new Buffer(21)
  var hash = bcrypto.ripemd160(this.getPublicKeyBuffer())
  var version = this.getNetwork().pubKeyHash
  payload.writeUInt8(version, 0)
  hash.copy(payload, 1)

  return base58check.encode(payload)
}

/**
 * @returns {Network}
 */
ECPair.prototype.getNetwork = function () {
  return this.network
}

ECPair.prototype.getPublicKeyBuffer = function () {
  return this.Q.getEncoded(this.compressed)
}

/**
 * Requires a private key (`d`) to be set.
 *
 * @param {Buffer} hash
 * @returns {ECSignature}
 */
ECPair.prototype.sign = function (hash) {
  if (!this.d) throw new Error('Missing private key')
  var native=secp256k1native.sign(hash, this.d.toBuffer(32))
  return ECSignature.parseNativeSecp256k1(native).signature
}

/**
 * Requires a private key (`d`) to be set.
 *
 * @returns {string}
 */
ECPair.prototype.toWIF = function () {
  if (!this.d) throw new Error('Missing private key')

  return wif.encode(this.network.wif, this.d.toBuffer(32), this.compressed)
}

/**
 * @param {Buffer} hash
 * @returns {boolean}
 */
ECPair.prototype.verify = function (hash, signature) {
  return secp256k1native.verify(hash, signature.toNativeSecp256k1(), this.Q.getEncoded(this.compressed))
}

module.exports = ECPair