text: /*!
   * scrypt.js - scrypt for decentraland
   * Copyright (c) 2016, Christopher Jeffrey (MIT License).
   * Copyright (c) 2016-2017, Manuel Araoz (MIT License).
   * https://github.com/decentraland/decentraland-node
   *
   * Ported from:
   * https://github.com/Tarsnap/scrypt/blob/master/lib/crypto/crypto_scrypt-ref.c
   *
   * Copyright 2009 Colin Percival
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  'use strict';
  
  var backend = require('./backend');
  var native = require('../utils/native').binding;
  var U32Array = typeof Uint32Array === 'function' ? Uint32Array : Array;
  
  /**
   * Javascript scrypt implementation. Scrypt is
   * used in bip38. Decentraland doesn't support bip38
   * yet, but here it is, just in case.
   * @param {Buffer} passwd
   * @param {Buffer} salt
   * @param {Number} N
   * @param {Number} r
   * @param {Number} p
   * @param {Number} len
   * @returns {Buffer}
   */
  
  function scrypt(passwd, salt, N, r, p, len) {
    var i, B, V, XY;
  
    if (r * p >= (1 << 30))
      throw new Error('EFBIG');
  
    if ((N & (N - 1)) !== 0 || N === 0)
      throw new Error('EINVAL');
  
    if (N > 0xffffffff)
      throw new Error('EINVAL');
  
    XY = new Buffer(256 * r);
    V = new Buffer(128 * r * N);
  
    B = backend.pbkdf2(passwd, salt, 1, p * 128 * r, 'sha256');
  
    for (i = 0; i < p; i++)
      smix(B, i * 128 * r, r, N, V, XY);
  
    return backend.pbkdf2(passwd, B, 1, len, 'sha256');
  }
  
  if (native)
    scrypt = native.scrypt;
  
  function salsa20_8(B) {
    var B32 = new U32Array(16);
    var x = new U32Array(16);
    var i;
  
    for (i = 0; i < 16; i++)
      B32[i] = B.readUInt32LE(i * 4, true);
  
    for (i = 0; i < 16; i++)
      x[i] = B32[i];
  
    for (i = 0; i < 8; i += 2) {
      x[4] ^= R(x[0] + x[12], 7);
      x[8] ^= R(x[4] + x[0], 9);
      x[12] ^= R(x[8] + x[4], 13);
      x[0] ^= R(x[12] + x[8], 18);
  
      x[9] ^= R(x[5] + x[1], 7);
      x[13] ^= R(x[9] + x[5], 9);
      x[1] ^= R(x[13] + x[9], 13);
      x[5] ^= R(x[1] + x[13], 18);
  
      x[14] ^= R(x[10] + x[6], 7);
      x[2] ^= R(x[14] + x[10], 9);
      x[6] ^= R(x[2] + x[14], 13);
      x[10] ^= R(x[6] + x[2], 18);
  
      x[3] ^= R(x[15] + x[11], 7);
      x[7] ^= R(x[3] + x[15], 9);
      x[11] ^= R(x[7] + x[3], 13);
      x[15] ^= R(x[11] + x[7], 18);
  
      x[1] ^= R(x[0] + x[3], 7);
      x[2] ^= R(x[1] + x[0], 9);
      x[3] ^= R(x[2] + x[1], 13);
      x[0] ^= R(x[3] + x[2], 18);
  
      x[6] ^= R(x[5] + x[4], 7);
      x[7] ^= R(x[6] + x[5], 9);
      x[4] ^= R(x[7] + x[6], 13);
      x[5] ^= R(x[4] + x[7], 18);
  
      x[11] ^= R(x[10] + x[9], 7);
      x[8] ^= R(x[11] + x[10], 9);
      x[9] ^= R(x[8] + x[11], 13);
      x[10] ^= R(x[9] + x[8], 18);
  
      x[12] ^= R(x[15] + x[14], 7);
      x[13] ^= R(x[12] + x[15], 9);
      x[14] ^= R(x[13] + x[12], 13);
      x[15] ^= R(x[14] + x[13], 18);
    }
  
    for (i = 0; i < 16; i++)
      B32[i] += x[i];
  
    for (i = 0; i < 16; i++)
      B.writeUInt32LE(B32[i], 4 * i, true);
  }
  
  function R(a, b) {
    return (a << b) | (a >>> (32 - b));
  }
  
  function blockmix_salsa8(B, Y, Yo, r) {
    var X = new Buffer(64);
    var i;
  
    blkcpy(X, B, 0, (2 * r - 1) * 64, 64);
  
    for (i = 0; i < 2 * r; i++) {
      blkxor(X, B, 0, i * 64, 64);
      salsa20_8(X);
      blkcpy(Y, X, Yo + i * 64, 0, 64);
    }
  
    for (i = 0; i < r; i++)
      blkcpy(B, Y, i * 64, Yo + (i * 2) * 64, 64);
  
    for (i = 0; i < r; i++)
      blkcpy(B, Y, (i + r) * 64, Yo + (i * 2 + 1) * 64, 64);
  }
  
  function integerify(B, r) {
    return B.readUInt32LE((2 * r - 1) * 64, true);
  }
  
  function smix(B, Bo, r, N, V, XY) {
    var X = XY;
    var Y = XY;
    var i;
    var j;
  
    blkcpy(X, B, 0, Bo, 128 * r);
  
    for (i = 0; i < N; i++) {
      blkcpy(V, X, i * (128 * r), 0, 128 * r);
      blockmix_salsa8(X, Y, 128 * r, r);
    }
  
    for (i = 0; i < N; i++) {
      j = integerify(X, r) & (N - 1);
      blkxor(X, V, 0, j * (128 * r), 128 * r);
      blockmix_salsa8(X, Y, 128 * r, r);
    }
  
    blkcpy(B, X, Bo, 0, 128 * r);
  }
  
  function blkcpy(dest, src, s1, s2, len) {
    src.copy(dest, s1, s2, s2 + len);
  }
  
  function blkxor(dest, src, s1, s2, len) {
    for (var i = 0; i < len; i++)
      dest[s1 + i] ^= src[s2 + i];
  }
  
  /*
   * Expose
   */
  
  module.exports = scrypt;
  