nacl-fast.js

import {getRandomBytesAsync} from '../expo-random'

(function(nacl) {
'use strict';

// Ported in 2014 by Dmitry Chestnykh and Devi Mandiri.
// Public domain.
//
// Implementation derived from TweetNaCl version 20140427.
// See for details: http://tweetnacl.cr.yp.to/

var gf = function(init) {
  var i, r = new Float64Array(16);
  if (init) for (i = 0; i < init.length; i++) r[i] = init[i];
  return r;
};

//  Pluggable, initialized in high-level API below.
var randombytes = function(/* x, n */) { throw new Error('no PRNG'); };

var _0 = new Uint8Array(16);
var _9 = new Uint8Array(32); _9[0] = 9;

var gf0 = gf(),
    gf1 = gf([1]),
    _121665 = gf([0xdb41, 1]),
    D = gf([0x78a3, 0x1359, 0x4dca, 0x75eb, 0xd8ab, 0x4141, 0x0a4d, 0x0070, 0xe898, 0x7779, 0x4079, 0x8cc7, 0xfe73, 0x2b6f, 0x6cee, 0x5203]),
    D2 = gf([0xf159, 0x26b2, 0x9b94, 0xebd6, 0xb156, 0x8283, 0x149a, 0x00e0, 0xd130, 0xeef3, 0x80f2, 0x198e, 0xfce7, 0x56df, 0xd9dc, 0x2406]),
    X = gf([0xd51a, 0x8f25, 0x2d60, 0xc956, 0xa7b2, 0x9525, 0xc760, 0x692c, 0xdc5c, 0xfdd6, 0xe231, 0xc0a4, 0x53fe, 0xcd6e, 0x36d3, 0x2169]),
    Y = gf([0x6658, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666]),
    I = gf([0xa0b0, 0x4a0e, 0x1b27, 0xc4ee, 0xe478, 0xad2f, 0x1806, 0x2f43, 0xd7a7, 0x3dfb, 0x0099, 0x2b4d, 0xdf0b, 0x4fc1, 0x2480, 0x2b83]);

function ts64(x, i, h, l) {
  x[i]   = (h >> 24) & 0xff;
  x[i+1] = (h >> 16) & 0xff;
  x[i+2] = (h >>  8) & 0xff;
  x[i+3] = h & 0xff;
  x[i+4] = (l >> 24)  & 0xff;
  x[i+5] = (l >> 16)  & 0xff;
  x[i+6] = (l >>  8)  & 0xff;
  x[i+7] = l & 0xff;
}

function vn(x, xi, y, yi, n) {
  var i,d = 0;
  for (i = 0; i < n; i++) d |= x[xi+i]^y[yi+i];
  return (1 & ((d - 1) >>> 8)) - 1;
}

function crypto_verify_16(x, xi, y, yi) {
  return vn(x,xi,y,yi,16);
}

function crypto_verify_32(x, xi, y, yi) {
  return vn(x,xi,y,yi,32);
}

function core_salsa20(o, p, k, c) {
  var j0  = c[ 0] & 0xff | (c[ 1] & 0xff)<<8 | (c[ 2] & 0xff)<<16 | (c[ 3] & 0xff)<<24,
      j1  = k[ 0] & 0xff | (k[ 1] & 0xff)<<8 | (k[ 2] & 0xff)<<16 | (k[ 3] & 0xff)<<24,
      j2  = k[ 4] & 0xff | (k[ 5] & 0xff)<<8 | (k[ 6] & 0xff)<<16 | (k[ 7] & 0xff)<<24,
      j3  = k[ 8] & 0xff | (k[ 9] & 0xff)<<8 | (k[10] & 0xff)<<16 | (k[11] & 0xff)<<24,
      j4  = k[12] & 0xff | (k[13] & 0xff)<<8 | (k[14] & 0xff)<<16 | (k[15] & 0xff)<<24,
      j5  = c[ 4] & 0xff | (c[ 5] & 0xff)<<8 | (c[ 6] & 0xff)<<16 | (c[ 7] & 0xff)<<24,
      j6  = p[ 0] & 0xff | (p[ 1] & 0xff)<<8 | (p[ 2] & 0xff)<<16 | (p[ 3] & 0xff)<<24,
      j7  = p[ 4] & 0xff | (p[ 5] & 0xff)<<8 | (p[ 6] & 0xff)<<16 | (p[ 7] & 0xff)<<24,
      j8  = p[ 8] & 0xff | (p[ 9] & 0xff)<<8 | (p[10] & 0xff)<<16 | (p[11] & 0xff)<<24,
      j9  = p[12] & 0xff | (p[13] & 0xff)<<8 | (p[14] & 0xff)<<16 | (p[15] & 0xff)<<24,
      j10 = c[ 8] & 0xff | (c[ 9] & 0xff)<<8 | (c[10] & 0xff)<<16 | (c[11] & 0xff)<<24,
      j11 = k[16] & 0xff | (k[17] & 0xff)<<8 | (k[18] & 0xff)<<16 | (k[19] & 0xff)<<24,
      j12 = k[20] & 0xff | (k[21] & 0xff)<<8 | (k[22] & 0xff)<<16 | (k[23] & 0xff)<<24,
      j13 = k[24] & 0xff | (k[25] & 0xff)<<8 | (k[26] & 0xff)<<16 | (k[27] & 0xff)<<24,
      j14 = k[28] & 0xff | (k[29] & 0xff)<<8 | (k[30] & 0xff)<<16 | (k[31] & 0xff)<<24,
      j15 = c[12] & 0xff | (c[13] & 0xff)<<8 | (c[14] & 0xff)<<16 | (c[15] & 0xff)<<24;

  var x0 = j0, x1 = j1, x2 = j2, x3 = j3, x4 = j4, x5 = j5, x6 = j6, x7 = j7,
      x8 = j8, x9 = j9, x10 = j10, x11 = j11, x12 = j12, x13 = j13, x14 = j14,
      x15 = j15, u;

  for (var i = 0; i < 20; i += 2) {
    u = x0 + x12 | 0;
    x4 ^= u<<7 | u>>>(32-7);
    u = x4 + x0 | 0;
    x8 ^= u<<9 | u>>>(32-9);
    u = x8 + x4 | 0;
    x12 ^= u<<13 | u>>>(32-13);
    u = x12 + x8 | 0;
    x0 ^= u<<18 | u>>>(32-18);

    u = x5 + x1 | 0;
    x9 ^= u<<7 | u>>>(32-7);
    u = x9 + x5 | 0;
    x13 ^= u<<9 | u>>>(32-9);
    u = x13 + x9 | 0;
    x1 ^= u<<13 | u>>>(32-13);
    u = x1 + x13 | 0;
    x5 ^= u<<18 | u>>>(32-18);

    u = x10 + x6 | 0;
    x14 ^= u<<7 | u>>>(32-7);
    u = x14 + x10 | 0;
    x2 ^= u<<9 | u>>>(32-9);
    u = x2 + x14 | 0;
    x6 ^= u<<13 | u>>>(32-13);
    u = x6 + x2 | 0;
    x10 ^= u<<18 | u>>>(32-18);

    u = x15 + x11 | 0;
    x3 ^= u<<7 | u>>>(32-7);
    u = x3 + x15 | 0;
    x7 ^= u<<9 | u>>>(32-9);
    u = x7 + x3 | 0;
    x11 ^= u<<13 | u>>>(32-13);
    u = x11 + x7 | 0;
    x15 ^= u<<18 | u>>>(32-18);

    u = x0 + x3 | 0;
    x1 ^= u<<7 | u>>>(32-7);
    u = x1 + x0 | 0;
    x2 ^= u<<9 | u>>>(32-9);
    u = x2 + x1 | 0;
    x3 ^= u<<13 | u>>>(32-13);
    u = x3 + x2 | 0;
    x0 ^= u<<18 | u>>>(32-18);

    u = x5 + x4 | 0;
    x6 ^= u<<7 | u>>>(32-7);
    u = x6 + x5 | 0;
    x7 ^= u<<9 | u>>>(32-9);
    u = x7 + x6 | 0;
    x4 ^= u<<13 | u>>>(32-13);
    u = x4 + x7 | 0;
    x5 ^= u<<18 | u>>>(32-18);

    u = x10 + x9 | 0;
    x11 ^= u<<7 | u>>>(32-7);
    u = x11 + x10 | 0;
    x8 ^= u<<9 | u>>>(32-9);
    u = x8 + x11 | 0;
    x9 ^= u<<13 | u>>>(32-13);
    u = x9 + x8 | 0;
    x10 ^= u<<18 | u>>>(32-18);

    u = x15 + x14 | 0;
    x12 ^= u<<7 | u>>>(32-7);
    u = x12 + x15 | 0;
    x13 ^= u<<9 | u>>>(32-9);
    u = x13 + x12 | 0;
    x14 ^= u<<13 | u>>>(32-13);
    u = x14 + x13 | 0;
    x15 ^= u<<18 | u>>>(32-18);
  }
   x0 =  x0 +  j0 | 0;
   x1 =  x1 +  j1 | 0;
   x2 =  x2 +  j2 | 0;
   x3 =  x3 +  j3 | 0;
   x4 =  x4 +  j4 | 0;
   x5 =  x5 +  j5 | 0;
   x6 =  x6 +  j6 | 0;
   x7 =  x7 +  j7 | 0;
   x8 =  x8 +  j8 | 0;
   x9 =  x9 +  j9 | 0;
  x10 = x10 + j10 | 0;
  x11 = x11 + j11 | 0;
  x12 = x12 + j12 | 0;
  x13 = x13 + j13 | 0;
  x14 = x14 + j14 | 0;
  x15 = x15 + j15 | 0;

  o[ 0] = x0 >>>  0 & 0xff;
  o[ 1] = x0 >>>  8 & 0xff;
  o[ 2] = x0 >>> 16 & 0xff;
  o[ 3] = x0 >>> 24 & 0xff;

  o[ 4] = x1 >>>  0 & 0xff;
  o[ 5] = x1 >>>  8 & 0xff;
  o[ 6] = x1 >>> 16 & 0xff;
  o[ 7] = x1 >>> 24 & 0xff;

  o[ 8] = x2 >>>  0 & 0xff;
  o[ 9] = x2 >>>  8 & 0xff;
  o[10] = x2 >>> 16 & 0xff;
  o[11] = x2 >>> 24 & 0xff;

  o[12] = x3 >>>  0 & 0xff;
  o[13] = x3 >>>  8 & 0xff;
  o[14] = x3 >>> 16 & 0xff;
  o[15] = x3 >>> 24 & 0xff;

  o[16] = x4 >>>  0 & 0xff;
  o[17] = x4 >>>  8 & 0xff;
  o[18] = x4 >>> 16 & 0xff;
  o[19] = x4 >>> 24 & 0xff;

  o[20] = x5 >>>  0 & 0xff;
  o[21] = x5 >>>  8 & 0xff;
  o[22] = x5 >>> 16 & 0xff;
  o[23] = x5 >>> 24 & 0xff;

  o[24] = x6 >>>  0 & 0xff;
  o[25] = x6 >>>  8 & 0xff;
  o[26] = x6 >>> 16 & 0xff;
  o[27] = x6 >>> 24 & 0xff;

  o[28] = x7 >>>  0 & 0xff;
  o[29] = x7 >>>  8 & 0xff;
  o[30] = x7 >>> 16 & 0xff;
  o[31] = x7 >>> 24 & 0xff;

  o[32] = x8 >>>  0 & 0xff;
  o[33] = x8 >>>  8 & 0xff;
  o[34] = x8 >>> 16 & 0xff;
  o[35] = x8 >>> 24 & 0xff;

  o[36] = x9 >>>  0 & 0xff;
  o[37] = x9 >>>  8 & 0xff;
  o[38] = x9 >>> 16 & 0xff;
  o[39] = x9 >>> 24 & 0xff;

  o[40] = x10 >>>  0 & 0xff;
  o[41] = x10 >>>  8 & 0xff;
  o[42] = x10 >>> 16 & 0xff;
  o[43] = x10 >>> 24 & 0xff;

  o[44] = x11 >>>  0 & 0xff;
  o[45] = x11 >>>  8 & 0xff;
  o[46] = x11 >>> 16 & 0xff;
  o[47] = x11 >>> 24 & 0xff;

  o[48] = x12 >>>  0 & 0xff;
  o[49] = x12 >>>  8 & 0xff;
  o[50] = x12 >>> 16 & 0xff;
  o[51] = x12 >>> 24 & 0xff;

  o[52] = x13 >>>  0 & 0xff;
  o[53] = x13 >>>  8 & 0xff;
  o[54] = x13 >>> 16 & 0xff;
  o[55] = x13 >>> 24 & 0xff;

  o[56] = x14 >>>  0 & 0xff;
  o[57] = x14 >>>  8 & 0xff;
  o[58] = x14 >>> 16 & 0xff;
  o[59] = x14 >>> 24 & 0xff;

  o[60] = x15 >>>  0 & 0xff;
  o[61] = x15 >>>  8 & 0xff;
  o[62] = x15 >>> 16 & 0xff;
  o[63] = x15 >>> 24 & 0xff;
}

function core_hsalsa20(o,p,k,c) {
  var j0  = c[ 0] & 0xff | (c[ 1] & 0xff)<<8 | (c[ 2] & 0xff)<<16 | (c[ 3] & 0xff)<<24,
      j1  = k[ 0] & 0xff | (k[ 1] & 0xff)<<8 | (k[ 2] & 0xff)<<16 | (k[ 3] & 0xff)<<24,
      j2  = k[ 4] & 0xff | (k[ 5] & 0xff)<<8 | (k[ 6] & 0xff)<<16 | (k[ 7] & 0xff)<<24,
      j3  = k[ 8] & 0xff | (k[ 9] & 0xff)<<8 | (k[10] & 0xff)<<16 | (k[11] & 0xff)<<24,
      j4  = k[12] & 0xff | (k[13] & 0xff)<<8 | (k[14] & 0xff)<<16 | (k[15] & 0xff)<<24,
      j5  = c[ 4] & 0xff | (c[ 5] & 0xff)<<8 | (c[ 6] & 0xff)<<16 | (c[ 7] & 0xff)<<24,
      j6  = p[ 0] & 0xff | (p[ 1] & 0xff)<<8 | (p[ 2] & 0xff)<<16 | (p[ 3] & 0xff)<<24,
      j7  = p[ 4] & 0xff | (p[ 5] & 0xff)<<8 | (p[ 6] & 0xff)<<16 | (p[ 7] & 0xff)<<24,
      j8  = p[ 8] & 0xff | (p[ 9] & 0xff)<<8 | (p[10] & 0xff)<<16 | (p[11] & 0xff)<<24,
      j9  = p[12] & 0xff | (p[13] & 0xff)<<8 | (p[14] & 0xff)<<16 | (p[15] & 0xff)<<24,
      j10 = c[ 8] & 0xff | (c[ 9] & 0xff)<<8 | (c[10] & 0xff)<<16 | (c[11] & 0xff)<<24,
      j11 = k[16] & 0xff | (k[17] & 0xff)<<8 | (k[18] & 0xff)<<16 | (k[19] & 0xff)<<24,
      j12 = k[20] & 0xff | (k[21] & 0xff)<<8 | (k[22] & 0xff)<<16 | (k[23] & 0xff)<<24,
      j13 = k[24] & 0xff | (k[25] & 0xff)<<8 | (k[26] & 0xff)<<16 | (k[27] & 0xff)<<24,
      j14 = k[28] & 0xff | (k[29] & 0xff)<<8 | (k[30] & 0xff)<<16 | (k[31] & 0xff)<<24,
      j15 = c[12] & 0xff | (c[13] & 0xff)<<8 | (c[14] & 0xff)<<16 | (c[15] & 0xff)<<24;

  var x0 = j0, x1 = j1, x2 = j2, x3 = j3, x4 = j4, x5 = j5, x6 = j6, x7 = j7,
      x8 = j8, x9 = j9, x10 = j10, x11 = j11, x12 = j12, x13 = j13, x14 = j14,
      x15 = j15, u;

  for (var i = 0; i < 20; i += 2) {
    u = x0 + x12 | 0;
    x4 ^= u<<7 | u>>>(32-7);
    u = x4 + x0 | 0;
    x8 ^= u<<9 | u>>>(32-9);
    u = x8 + x4 | 0;
    x12 ^= u<<13 | u>>>(32-13);
    u = x12 + x8 | 0;
    x0 ^= u<<18 | u>>>(32-18);

    u = x5 + x1 | 0;
    x9 ^= u<<7 | u>>>(32-7);
    u = x9 + x5 | 0;
    x13 ^= u<<9 | u>>>(32-9);
    u = x13 + x9 | 0;
    x1 ^= u<<13 | u>>>(32-13);
    u = x1 + x13 | 0;
    x5 ^= u<<18 | u>>>(32-18);

    u = x10 + x6 | 0;
    x14 ^= u<<7 | u>>>(32-7);
    u = x14 + x10 | 0;
    x2 ^= u<<9 | u>>>(32-9);
    u = x2 + x14 | 0;
    x6 ^= u<<13 | u>>>(32-13);
    u = x6 + x2 | 0;
    x10 ^= u<<18 | u>>>(32-18);

    u = x15 + x11 | 0;
    x3 ^= u<<7 | u>>>(32-7);
    u = x3 + x15 | 0;
    x7 ^= u<<9 | u>>>(32-9);
    u = x7 + x3 | 0;
    x11 ^= u<<13 | u>>>(32-13);
    u = x11 + x7 | 0;
    x15 ^= u<<18 | u>>>(32-18);

    u = x0 + x3 | 0;
    x1 ^= u<<7 | u>>>(32-7);
    u = x1 + x0 | 0;
    x2 ^= u<<9 | u>>>(32-9);
    u = x2 + x1 | 0;
    x3 ^= u<<13 | u>>>(32-13);
    u = x3 + x2 | 0;
    x0 ^= u<<18 | u>>>(32-18);

    u = x5 + x4 | 0;
    x6 ^= u<<7 | u>>>(32-7);
    u = x6 + x5 | 0;
    x7 ^= u<<9 | u>>>(32-9);
    u = x7 + x6 | 0;
    x4 ^= u<<13 | u>>>(32-13);
    u = x4 + x7 | 0;
    x5 ^= u<<18 | u>>>(32-18);

    u = x10 + x9 | 0;
    x11 ^= u<<7 | u>>>(32-7);
    u = x11 + x10 | 0;
    x8 ^= u<<9 | u>>>(32-9);
    u = x8 + x11 | 0;
    x9 ^= u<<13 | u>>>(32-13);
    u = x9 + x8 | 0;
    x10 ^= u<<18 | u>>>(32-18);

    u = x15 + x14 | 0;
    x12 ^= u<<7 | u>>>(32-7);
    u = x12 + x15 | 0;
    x13 ^= u<<9 | u>>>(32-9);
    u = x13 + x12 | 0;
    x14 ^= u<<13 | u>>>(32-13);
    u = x14 + x13 | 0;
    x15 ^= u<<18 | u>>>(32-18);
  }

  o[ 0] = x0 >>>  0 & 0xff;
  o[ 1] = x0 >>>  8 & 0xff;
  o[ 2] = x0 >>> 16 & 0xff;
  o[ 3] = x0 >>> 24 & 0xff;

  o[ 4] = x5 >>>  0 & 0xff;
  o[ 5] = x5 >>>  8 & 0xff;
  o[ 6] = x5 >>> 16 & 0xff;
  o[ 7] = x5 >>> 24 & 0xff;

  o[ 8] = x10 >>>  0 & 0xff;
  o[ 9] = x10 >>>  8 & 0xff;
  o[10] = x10 >>> 16 & 0xff;
  o[11] = x10 >>> 24 & 0xff;

  o[12] = x15 >>>  0 & 0xff;
  o[13] = x15 >>>  8 & 0xff;
  o[14] = x15 >>> 16 & 0xff;
  o[15] = x15 >>> 24 & 0xff;

  o[16] = x6 >>>  0 & 0xff;
  o[17] = x6 >>>  8 & 0xff;
  o[18] = x6 >>> 16 & 0xff;
  o[19] = x6 >>> 24 & 0xff;

  o[20] = x7 >>>  0 & 0xff;
  o[21] = x7 >>>  8 & 0xff;
  o[22] = x7 >>> 16 & 0xff;
  o[23] = x7 >>> 24 & 0xff;

  o[24] = x8 >>>  0 & 0xff;
  o[25] = x8 >>>  8 & 0xff;
  o[26] = x8 >>> 16 & 0xff;
  o[27] = x8 >>> 24 & 0xff;

  o[28] = x9 >>>  0 & 0xff;
  o[29] = x9 >>>  8 & 0xff;
  o[30] = x9 >>> 16 & 0xff;
  o[31] = x9 >>> 24 & 0xff;
}

function crypto_core_salsa20(out,inp,k,c) {
  core_salsa20(out,inp,k,c);
}

function crypto_core_hsalsa20(out,inp,k,c) {
  core_hsalsa20(out,inp,k,c);
}

var sigma = new Uint8Array([101, 120, 112, 97, 110, 100, 32, 51, 50, 45, 98, 121, 116, 101, 32, 107]);
            // "expand 32-byte k"

function crypto_stream_salsa20_xor(c,cpos,m,mpos,b,n,k) {
  var z = new Uint8Array(16), x = new Uint8Array(64);
  var u, i;
  for (i = 0; i < 16; i++) z[i] = 0;
  for (i = 0; i < 8; i++) z[i] = n[i];
  while (b >= 64) {
    crypto_core_salsa20(x,z,k,sigma);
    for (i = 0; i < 64; i++) c[cpos+i] = m[mpos+i] ^ x[i];
    u = 1;
    for (i = 8; i < 16; i++) {
      u = u + (z[i] & 0xff) | 0;
      z[i] = u & 0xff;
      u >>>= 8;
    }
    b -= 64;
    cpos += 64;
    mpos += 64;
  }
  if (b > 0) {
    crypto_core_salsa20(x,z,k,sigma);
    for (i = 0; i < b; i++) c[cpos+i] = m[mpos+i] ^ x[i];
  }
  return 0;
}

function crypto_stream_salsa20(c,cpos,b,n,k) {
  var z = new Uint8Array(16), x = new Uint8Array(64);
  var u, i;
  for (i = 0; i < 16; i++) z[i] = 0;
  for (i = 0; i < 8; i++) z[i] = n[i];
  while (b >= 64) {
    crypto_core_salsa20(x,z,k,sigma);
    for (i = 0; i < 64; i++) c[cpos+i] = x[i];
    u = 1;
    for (i = 8; i < 16; i++) {
      u = u + (z[i] & 0xff) | 0;
      z[i] = u & 0xff;
      u >>>= 8;
    }
    b -= 64;
    cpos += 64;
  }
  if (b > 0) {
    crypto_core_salsa20(x,z,k,sigma);
    for (i = 0; i < b; i++) c[cpos+i] = x[i];
  }
  return 0;
}

function crypto_stream(c,cpos,d,n,k) {
  var s = new Uint8Array(32);
  crypto_core_hsalsa20(s,n,k,sigma);
  var sn = new Uint8Array(8);
  for (var i = 0; i < 8; i++) sn[i] = n[i+16];
  return crypto_stream_salsa20(c,cpos,d,sn,s);
}

function crypto_stream_xor(c,cpos,m,mpos,d,n,k) {
  var s = new Uint8Array(32);
  crypto_core_hsalsa20(s,n,k,sigma);
  var sn = new Uint8Array(8);
  for (var i = 0; i < 8; i++) sn[i] = n[i+16];
  return crypto_stream_salsa20_xor(c,cpos,m,mpos,d,sn,s);
}

/*
* Port of Andrew Moon's Poly1305-donna-16. Public domain.
* https://github.com/floodyberry/poly1305-donna
*/

var poly1305 = function(key) {
  this.buffer = new Uint8Array(16);
  this.r = new Uint16Array(10);
  this.h = new Uint16Array(10);
  this.pad = new Uint16Array(8);
  this.leftover = 0;
  this.fin = 0;

  var t0, t1, t2, t3, t4, t5, t6, t7;

  t0 = key[ 0] & 0xff | (key[ 1] & 0xff) << 8; this.r[0] = ( t0                     ) & 0x1fff;
  t1 = key[ 2] & 0xff | (key[ 3] & 0xff) << 8; this.r[1] = ((t0 >>> 13) | (t1 <<  3)) & 0x1fff;
  t2 = key[ 4] & 0xff | (key[ 5] & 0xff) << 8; this.r[2] = ((t1 >>> 10) | (t2 <<  6)) & 0x1f03;
  t3 = key[ 6] & 0xff | (key[ 7] & 0xff) << 8; this.r[3] = ((t2 >>>  7) | (t3 <<  9)) & 0x1fff;
  t4 = key[ 8] & 0xff | (key[ 9] & 0xff) << 8; this.r[4] = ((t3 >>>  4) | (t4 << 12)) & 0x00ff;
  this.r[5] = ((t4 >>>  1)) & 0x1ffe;
  t5 = key[10] & 0xff | (key[11] & 0xff) << 8; this.r[6] = ((t4 >>> 14) | (t5 <<  2)) & 0x1fff;
  t6 = key[12] & 0xff | (key[13] & 0xff) << 8; this.r[7] = ((t5 >>> 11) | (t6 <<  5)) & 0x1f81;
  t7 = key[14] & 0xff | (key[15] & 0xff) << 8; this.r[8] = ((t6 >>>  8) | (t7 <<  8)) & 0x1fff;
  this.r[9] = ((t7 >>>  5)) & 0x007f;

  this.pad[0] = key[16] & 0xff | (key[17] & 0xff) << 8;
  this.pad[1] = key[18] & 0xff | (key[19] & 0xff) << 8;
  this.pad[2] = key[20] & 0xff | (key[21] & 0xff) << 8;
  this.pad[3] = key[22] & 0xff | (key[23] & 0xff) << 8;
  this.pad[4] = key[24] & 0xff | (key[25] & 0xff) << 8;
  this.pad[5] = key[26] & 0xff | (key[27] & 0xff) << 8;
  this.pad[6] = key[28] & 0xff | (key[29] & 0xff) << 8;
  this.pad[7] = key[30] & 0xff | (key[31] & 0xff) << 8;
};

poly1305.prototype.blocks = function(m, mpos, bytes) {
  var hibit = this.fin ? 0 : (1 << 11);
  var t0, t1, t2, t3, t4, t5, t6, t7, c;
  var d0, d1, d2, d3, d4, d5, d6, d7, d8, d9;

  var h0 = this.h[0],
      h1 = this.h[1],
      h2 = this.h[2],
      h3 = this.h[3],
      h4 = this.h[4],
      h5 = this.h[5],
      h6 = this.h[6],
      h7 = this.h[7],
      h8 = this.h[8],
      h9 = this.h[9];

  var r0 = this.r[0],
      r1 = this.r[1],
      r2 = this.r[2],
      r3 = this.r[3],
      r4 = this.r[4],
      r5 = this.r[5],
      r6 = this.r[6],
      r7 = this.r[7],
      r8 = this.r[8],
      r9 = this.r[9];

  while (bytes >= 16) {
    t0 = m[mpos+ 0] & 0xff | (m[mpos+ 1] & 0xff) << 8; h0 += ( t0                     ) & 0x1fff;
    t1 = m[mpos+ 2] & 0xff | (m[mpos+ 3] & 0xff) << 8; h1 += ((t0 >>> 13) | (t1 <<  3)) & 0x1fff;
    t2 = m[mpos+ 4] & 0xff | (m[mpos+ 5] & 0xff) << 8; h2 += ((t1 >>> 10) | (t2 <<  6)) & 0x1fff;
    t3 = m[mpos+ 6] & 0xff | (m[mpos+ 7] & 0xff) << 8; h3 += ((t2 >>>  7) | (t3 <<  9)) & 0x1fff;
    t4 = m[mpos+ 8] & 0xff | (m[mpos+ 9] & 0xff) << 8; h4 += ((t3 >>>  4) | (t4 << 12)) & 0x1fff;
    h5 += ((t4 >>>  1)) & 0x1fff;
    t5 = m[mpos+10] & 0xff | (m[mpos+11] & 0xff) << 8; h6 += ((t4 >>> 14) | (t5 <<  2)) & 0x1fff;
    t6 = m[mpos+12] & 0xff | (m[mpos+13] & 0xff) << 8; h7 += ((t5 >>> 11) | (t6 <<  5)) & 0x1fff;
    t7 = m[mpos+14] & 0xff | (m[mpos+15] & 0xff) << 8; h8 += ((t6 >>>  8) | (t7 <<  8)) & 0x1fff;
    h9 += ((t7 >>> 5)) | hibit;

    c = 0;

    d0 = c;
    d0 += h0 * r0;
    d0 += h1 * (5 * r9);
    d0 += h2 * (5 * r8);
    d0 += h3 * (5 * r7);
    d0 += h4 * (5 * r6);
    c = (d0 >>> 13); d0 &= 0x1fff;
    d0 += h5 * (5 * r5);
    d0 += h6 * (5 * r4);
    d0 += h7 * (5 * r3);
    d0 += h8 * (5 * r2);
    d0 += h9 * (5 * r1);
    c += (d0 >>> 13); d0 &= 0x1fff;

    d1 = c;
    d1 += h0 * r1;
    d1 += h1 * r0;
    d1 += h2 * (5 * r9);
    d1 += h3 * (5 * r8);
    d1 += h4 * (5 * r7);
    c = (d1 >>> 13); d1 &= 0x1fff;
    d1 += h5 * (5 * r6);
    d1 += h6 * (5 * r5);
    d1 += h7 * (5 * r4);
    d1 += h8 * (5 * r3);
    d1 += h9 * (5 * r2);
    c += (d1 >>> 13); d1 &= 0x1fff;

    d2 = c;
    d2 += h0 * r2;
    d2 += h1 * r1;
    d2 += h2 * r0;
    d2 += h3 * (5 * r9);
    d2 += h4 * (5 * r8);
    c = (d2 >>> 13); d2 &= 0x1fff;
    d2 += h5 * (5 * r7);
    d2 += h6 * (5 * r6);
    d2 += h7 * (5 * r5);
    d2 += h8 * (5 * r4);
    d2 += h9 * (5 * r3);
    c += (d2 >>> 13); d2 &= 0x1fff;

    d3 = c;
    d3 += h0 * r3;
    d3 += h1 * r2;
    d3 += h2 * r1;
    d3 += h3 * r0;
    d3 += h4 * (5 * r9);
    c = (d3 >>> 13); d3 &= 0x1fff;
    d3 += h5 * (5 * r8);
    d3 += h6 * (5 * r7);
    d3 += h7 * (5 * r6);
    d3 += h8 * (5 * r5);
    d3 += h9 * (5 * r4);
    c += (d3 >>> 13); d3 &= 0x1fff;

    d4 = c;
    d4 += h0 * r4;
    d4 += h1 * r3;
    d4 += h2 * r2;
    d4 += h3 * r1;
    d4 += h4 * r0;
    c = (d4 >>> 13); d4 &= 0x1fff;
    d4 += h5 * (5 * r9);
    d4 += h6 * (5 * r8);
    d4 += h7 * (5 * r7);
    d4 += h8 * (5 * r6);
    d4 += h9 * (5 * r5);
    c += (d4 >>> 13); d4 &= 0x1fff;

    d5 = c;
    d5 += h0 * r5;
    d5 += h1 * r4;
    d5 += h2 * r3;
    d5 += h3 * r2;
    d5 += h4 * r1;
    c = (d5 >>> 13); d5 &= 0x1fff;
    d5 += h5 * r0;
    d5 += h6 * (5 * r9);
    d5 += h7 * (5 * r8);
    d5 += h8 * (5 * r7);
    d5 += h9 * (5 * r6);
    c += (d5 >>> 13); d5 &= 0x1fff;

    d6 = c;
    d6 += h0 * r6;
    d6 += h1 * r5;
    d6 += h2 * r4;
    d6 += h3 * r3;
    d6 += h4 * r2;
    c = (d6 >>> 13); d6 &= 0x1fff;
    d6 += h5 * r1;
    d6 += h6 * r0;
    d6 += h7 * (5 * r9);
    d6 += h8 * (5 * r8);
    d6 += h9 * (5 * r7);
    c += (d6 >>> 13); d6 &= 0x1fff;

    d7 = c;
    d7 += h0 * r7;
    d7 += h1 * r6;
    d7 += h2 * r5;
    d7 += h3 * r4;
    d7 += h4 * r3;
    c = (d7 >>> 13); d7 &= 0x1fff;
    d7 += h5 * r2;
    d7 += h6 * r1;
    d7 += h7 * r0;
    d7 += h8 * (5 * r9);
    d7 += h9 * (5 * r8);
    c += (d7 >>> 13); d7 &= 0x1fff;

    d8 = c;
    d8 += h0 * r8;
    d8 += h1 * r7;
    d8 += h2 * r6;
    d8 += h3 * r5;
    d8 += h4 * r4;
    c = (d8 >>> 13); d8 &= 0x1fff;
    d8 += h5 * r3;
    d8 += h6 * r2;
    d8 += h7 * r1;
    d8 += h8 * r0;
    d8 += h9 * (5 * r9);
    c += (d8 >>> 13); d8 &= 0x1fff;

    d9 = c;
    d9 += h0 * r9;
    d9 += h1 * r8;
    d9 += h2 * r7;
    d9 += h3 * r6;
    d9 += h4 * r5;
    c = (d9 >>> 13); d9 &= 0x1fff;
    d9 += h5 * r4;
    d9 += h6 * r3;
    d9 += h7 * r2;
    d9 += h8 * r1;
    d9 += h9 * r0;
    c += (d9 >>> 13); d9 &= 0x1fff;

    c = (((c << 2) + c)) | 0;
    c = (c + d0) | 0;
    d0 = c & 0x1fff;
    c = (c >>> 13);
    d1 += c;

    h0 = d0;
    h1 = d1;
    h2 = d2;
    h3 = d3;
    h4 = d4;
    h5 = d5;
    h6 = d6;
    h7 = d7;
    h8 = d8;
    h9 = d9;

    mpos += 16;
    bytes -= 16;
  }
  this.h[0] = h0;
  this.h[1] = h1;
  this.h[2] = h2;
  this.h[3] = h3;
  this.h[4] = h4;
  this.h[5] = h5;
  this.h[6] = h6;
  this.h[7] = h7;
  this.h[8] = h8;
  this.h[9] = h9;
};

poly1305.prototype.finish = function(mac, macpos) {
  var g = new Uint16Array(10);
  var c, mask, f, i;

  if (this.leftover) {
    i = this.leftover;
    this.buffer[i++] = 1;
    for (; i < 16; i++) this.buffer[i] = 0;
    this.fin = 1;
    this.blocks(this.buffer, 0, 16);
  }

  c = this.h[1] >>> 13;
  this.h[1] &= 0x1fff;
  for (i = 2; i < 10; i++) {
    this.h[i] += c;
    c = this.h[i] >>> 13;
    this.h[i] &= 0x1fff;
  }
  this.h[0] += (c * 5);
  c = this.h[0] >>> 13;
  this.h[0] &= 0x1fff;
  this.h[1] += c;
  c = this.h[1] >>> 13;
  this.h[1] &= 0x1fff;
  this.h[2] += c;

  g[0] = this.h[0] + 5;
  c = g[0] >>> 13;
  g[0] &= 0x1fff;
  for (i = 1; i < 10; i++) {
    g[i] = this.h[i] + c;
    c = g[i] >>> 13;
    g[i] &= 0x1fff;
  }
  g[9] -= (1 << 13);

  mask = (c ^ 1) - 1;
  for (i = 0; i < 10; i++) g[i] &= mask;
  mask = ~mask;
  for (i = 0; i < 10; i++) this.h[i] = (this.h[i] & mask) | g[i];

  this.h[0] = ((this.h[0]       ) | (this.h[1] << 13)                    ) & 0xffff;
  this.h[1] = ((this.h[1] >>>  3) | (this.h[2] << 10)                    ) & 0xffff;
  this.h[2] = ((this.h[2] >>>  6) | (this.h[3] <<  7)                    ) & 0xffff;
  this.h[3] = ((this.h[3] >>>  9) | (this.h[4] <<  4)                    ) & 0xffff;
  this.h[4] = ((this.h[4] >>> 12) | (this.h[5] <<  1) | (this.h[6] << 14)) & 0xffff;
  this.h[5] = ((this.h[6] >>>  2) | (this.h[7] << 11)                    ) & 0xffff;
  this.h[6] = ((this.h[7] >>>  5) | (this.h[8] <<  8)                    ) & 0xffff;
  this.h[7] = ((this.h[8] >>>  8) | (this.h[9] <<  5)                    ) & 0xffff;

  f = this.h[0] + this.pad[0];
  this.h[0] = f & 0xffff;
  for (i = 1; i < 8; i++) {
    f = (((this.h[i] + this.pad[i]) | 0) + (f >>> 16)) | 0;
    this.h[i] = f & 0xffff;
  }

  mac[macpos+ 0] = (this.h[0] >>> 0) & 0xff;
  mac[macpos+ 1] = (this.h[0] >>> 8) & 0xff;
  mac[macpos+ 2] = (this.h[1] >>> 0) & 0xff;
  mac[macpos+ 3] = (this.h[1] >>> 8) & 0xff;
  mac[macpos+ 4] = (this.h[2] >>> 0) & 0xff;
  mac[macpos+ 5] = (this.h[2] >>> 8) & 0xff;
  mac[macpos+ 6] = (this.h[3] >>> 0) & 0xff;
  mac[macpos+ 7] = (this.h[3] >>> 8) & 0xff;
  mac[macpos+ 8] = (this.h[4] >>> 0) & 0xff;
  mac[macpos+ 9] = (this.h[4] >>> 8) & 0xff;
  mac[macpos+10] = (this.h[5] >>> 0) & 0xff;
  mac[macpos+11] = (this.h[5] >>> 8) & 0xff;
  mac[macpos+12] = (this.h[6] >>> 0) & 0xff;
  mac[macpos+13] = (this.h[6] >>> 8) & 0xff;
  mac[macpos+14] = (this.h[7] >>> 0) & 0xff;
  mac[macpos+15] = (this.h[7] >>> 8) & 0xff;
};

poly1305.prototype.update = function(m, mpos, bytes) {
  var i, want;

  if (this.leftover) {
    want = (16 - this.leftover);
    if (want > bytes)
      want = bytes;
    for (i = 0; i < want; i++)
      this.buffer[this.leftover + i] = m[mpos+i];
    bytes -= want;
    mpos += want;
    this.leftover += want;
    if (this.leftover < 16)
      return;
    this.blocks(this.buffer, 0, 16);
    this.leftover = 0;
  }

  if (bytes >= 16) {
    want = bytes - (bytes % 16);
    this.blocks(m, mpos, want);
    mpos += want;
    bytes -= want;
  }

  if (bytes) {
    for (i = 0; i < bytes; i++)
      this.buffer[this.leftover + i] = m[mpos+i];
    this.leftover += bytes;
  }
};

function crypto_onetimeauth(out, outpos, m, mpos, n, k) {
  var s = new poly1305(k);
  s.update(m, mpos, n);
  s.finish(out, outpos);
  return 0;
}

function crypto_onetimeauth_verify(h, hpos, m, mpos, n, k) {
  var x = new Uint8Array(16);
  crypto_onetimeauth(x,0,m,mpos,n,k);
  return crypto_verify_16(h,hpos,x,0);
}

function crypto_secretbox(c,m,d,n,k) {
  var i;
  if (d < 32) return -1;
  crypto_stream_xor(c,0,m,0,d,n,k);
  crypto_onetimeauth(c, 16, c, 32, d - 32, c);
  for (i = 0; i < 16; i++) c[i] = 0;
  return 0;
}

function crypto_secretbox_open(m,c,d,n,k) {
  var i;
  var x = new Uint8Array(32);
  if (d < 32) return -1;
  crypto_stream(x,0,32,n,k);
  if (crypto_onetimeauth_verify(c, 16,c, 32,d - 32,x) !== 0) return -1;
  crypto_stream_xor(m,0,c,0,d,n,k);
  for (i = 0; i < 32; i++) m[i] = 0;
  return 0;
}

function set25519(r, a) {
  var i;
  for (i = 0; i < 16; i++) r[i] = a[i]|0;
}

function car25519(o) {
  var i, v, c = 1;
  for (i = 0; i < 16; i++) {
    v = o[i] + c + 65535;
    c = Math.floor(v / 65536);
    o[i] = v - c * 65536;
  }
  o[0] += c-1 + 37 * (c-1);
}

function sel25519(p, q, b) {
  var t, c = ~(b-1);
  for (var i = 0; i < 16; i++) {
    t = c & (p[i] ^ q[i]);
    p[i] ^= t;
    q[i] ^= t;
  }
}

function pack25519(o, n) {
  var i, j, b;
  var m = gf(), t = gf();
  for (i = 0; i < 16; i++) t[i] = n[i];
  car25519(t);
  car25519(t);
  car25519(t);
  for (j = 0; j < 2; j++) {
    m[0] = t[0] - 0xffed;
    for (i = 1; i < 15; i++) {
      m[i] = t[i] - 0xffff - ((m[i-1]>>16) & 1);
      m[i-1] &= 0xffff;
    }
    m[15] = t[15] - 0x7fff - ((m[14]>>16) & 1);
    b = (m[15]>>16) & 1;
    m[14] &= 0xffff;
    sel25519(t, m, 1-b);
  }
  for (i = 0; i < 16; i++) {
    o[2*i] = t[i] & 0xff;
    o[2*i+1] = t[i]>>8;
  }
}

function neq25519(a, b) {
  var c = new Uint8Array(32), d = new Uint8Array(32);
  pack25519(c, a);
  pack25519(d, b);
  return crypto_verify_32(c, 0, d, 0);
}

function par25519(a) {
  var d = new Uint8Array(32);
  pack25519(d, a);
  return d[0] & 1;
}

function unpack25519(o, n) {
  var i;
  for (i = 0; i < 16; i++) o[i] = n[2*i] + (n[2*i+1] << 8);
  o[15] &= 0x7fff;
}

function A(o, a, b) {
  for (var i = 0; i < 16; i++) o[i] = a[i] + b[i];
}

function Z(o, a, b) {
  for (var i = 0; i < 16; i++) o[i] = a[i] - b[i];
}

function M(o, a, b) {
  var v, c,
     t0 = 0,  t1 = 0,  t2 = 0,  t3 = 0,  t4 = 0,  t5 = 0,  t6 = 0,  t7 = 0,
     t8 = 0,  t9 = 0, t10 = 0, t11 = 0, t12 = 0, t13 = 0, t14 = 0, t15 = 0,
    t16 = 0, t17 = 0, t18 = 0, t19 = 0, t20 = 0, t21 = 0, t22 = 0, t23 = 0,
    t24 = 0, t25 = 0, t26 = 0, t27 = 0, t28 = 0, t29 = 0, t30 = 0,
    b0 = b[0],
    b1 = b[1],
    b2 = b[2],
    b3 = b[3],
    b4 = b[4],
    b5 = b[5],
    b6 = b[6],
    b7 = b[7],
    b8 = b[8],
    b9 = b[9],
    b10 = b[10],
    b11 = b[11],
    b12 = b[12],
    b13 = b[13],
    b14 = b[14],
    b15 = b[15];

  v = a[0];
  t0 += v * b0;
  t1 += v * b1;
  t2 += v * b2;
  t3 += v * b3;
  t4 += v * b4;
  t5 += v * b5;
  t6 += v * b6;
  t7 += v * b7;
  t8 += v * b8;
  t9 += v * b9;
  t10 += v * b10;
  t11 += v * b11;
  t12 += v * b12;
  t13 += v * b13;
  t14 += v * b14;
  t15 += v * b15;
  v = a[1];
  t1 += v * b0;
  t2 += v * b1;
  t3 += v * b2;
  t4 += v * b3;
  t5 += v * b4;
  t6 += v * b5;
  t7 += v * b6;
  t8 += v * b7;
  t9 += v * b8;
  t10 += v * b9;
  t11 += v * b10;
  t12 += v * b11;
  t13 += v * b12;
  t14 += v * b13;
  t15 += v * b14;
  t16 += v * b15;
  v = a[2];
  t2 += v * b0;
  t3 += v * b1;
  t4 += v * b2;
  t5 += v * b3;
  t6 += v * b4;
  t7 += v * b5;
  t8 += v * b6;
  t9 += v * b7;
  t10 += v * b8;
  t11 += v * b9;
  t12 += v * b10;
  t13 += v * b11;
  t14 += v * b12;
  t15 += v * b13;
  t16 += v * b14;
  t17 += v * b15;
  v = a[3];
  t3 += v * b0;
  t4 += v * b1;
  t5 += v * b2;
  t6 += v * b3;
  t7 += v * b4;
  t8 += v * b5;
  t9 += v * b6;
  t10 += v * b7;
  t11 += v * b8;
  t12 += v * b9;
  t13 += v * b10;
  t14 += v * b11;
  t15 += v * b12;
  t16 += v * b13;
  t17 += v * b14;
  t18 += v * b15;
  v = a[4];
  t4 += v * b0;
  t5 += v * b1;
  t6 += v * b2;
  t7 += v * b3;
  t8 += v * b4;
  t9 += v * b5;
  t10 += v * b6;
  t11 += v * b7;
  t12 += v * b8;
  t13 += v * b9;
  t14 += v * b10;
  t15 += v * b11;
  t16 += v * b12;
  t17 += v * b13;
  t18 += v * b14;
  t19 += v * b15;
  v = a[5];
  t5 += v * b0;
  t6 += v * b1;
  t7 += v * b2;
  t8 += v * b3;
  t9 += v * b4;
  t10 += v * b5;
  t11 += v * b6;
  t12 += v * b7;
  t13 += v * b8;
  t14 += v * b9;
  t15 += v * b10;
  t16 += v * b11;
  t17 += v * b12;
  t18 += v * b13;
  t19 += v * b14;
  t20 += v * b15;
  v = a[6];
  t6 += v * b0;
  t7 += v * b1;
  t8 += v * b2;
  t9 += v * b3;
  t10 += v * b4;
  t11 += v * b5;
  t12 += v * b6;
  t13 += v * b7;
  t14 += v * b8;
  t15 += v * b9;
  t16 += v * b10;
  t17 += v * b11;
  t18 += v * b12;
  t19 += v * b13;
  t20 += v * b14;
  t21 += v * b15;
  v = a[7];
  t7 += v * b0;
  t8 += v * b1;
  t9 += v * b2;
  t10 += v * b3;
  t11 += v * b4;
  t12 += v * b5;
  t13 += v * b6;
  t14 += v * b7;
  t15 += v * b8;
  t16 += v * b9;
  t17 += v * b10;
  t18 += v * b11;
  t19 += v * b12;
  t20 += v * b13;
  t21 += v * b14;
  t22 += v * b15;
  v = a[8];
  t8 += v * b0;
  t9 += v * b1;
  t10 += v * b2;
  t11 += v * b3;
  t12 += v * b4;
  t13 += v * b5;
  t14 += v * b6;
  t15 += v * b7;
  t16 += v * b8;
  t17 += v * b9;
  t18 += v * b10;
  t19 += v * b11;
  t20 += v * b12;
  t21 += v * b13;
  t22 += v * b14;
  t23 += v * b15;
  v = a[9];
  t9 += v * b0;
  t10 += v * b1;
  t11 += v * b2;
  t12 += v * b3;
  t13 += v * b4;
  t14 += v * b5;
  t15 += v * b6;
  t16 += v * b7;
  t17 += v * b8;
  t18 += v * b9;
  t19 += v * b10;
  t20 += v * b11;
  t21 += v * b12;
  t22 += v * b13;
  t23 += v * b14;
  t24 += v * b15;
  v = a[10];
  t10 += v * b0;
  t11 += v * b1;
  t12 += v * b2;
  t13 += v * b3;
  t14 += v * b4;
  t15 += v * b5;
  t16 += v * b6;
  t17 += v * b7;
  t18 += v * b8;
  t19 += v * b9;
  t20 += v * b10;
  t21 += v * b11;
  t22 += v * b12;
  t23 += v * b13;
  t24 += v * b14;
  t25 += v * b15;
  v = a[11];
  t11 += v * b0;
  t12 += v * b1;
  t13 += v * b2;
  t14 += v * b3;
  t15 += v * b4;
  t16 += v * b5;
  t17 += v * b6;
  t18 += v * b7;
  t19 += v * b8;
  t20 += v * b9;
  t21 += v * b10;
  t22 += v * b11;
  t23 += v * b12;
  t24 += v * b13;
  t25 += v * b14;
  t26 += v * b15;
  v = a[12];
  t12 += v * b0;
  t13 += v * b1;
  t14 += v * b2;
  t15 += v * b3;
  t16 += v * b4;
  t17 += v * b5;
  t18 += v * b6;
  t19 += v * b7;
  t20 += v * b8;
  t21 += v * b9;
  t22 += v * b10;
  t23 += v * b11;
  t24 += v * b12;
  t25 += v * b13;
  t26 += v * b14;
  t27 += v * b15;
  v = a[13];
  t13 += v * b0;
  t14 += v * b1;
  t15 += v * b2;
  t16 += v * b3;
  t17 += v * b4;
  t18 += v * b5;
  t19 += v * b6;
  t20 += v * b7;
  t21 += v * b8;
  t22 += v * b9;
  t23 += v * b10;
  t24 += v * b11;
  t25 += v * b12;
  t26 += v * b13;
  t27 += v * b14;
  t28 += v * b15;
  v = a[14];
  t14 += v * b0;
  t15 += v * b1;
  t16 += v * b2;
  t17 += v * b3;
  t18 += v * b4;
  t19 += v * b5;
  t20 += v * b6;
  t21 += v * b7;
  t22 += v * b8;
  t23 += v * b9;
  t24 += v * b10;
  t25 += v * b11;
  t26 += v * b12;
  t27 += v * b13;
  t28 += v * b14;
  t29 += v * b15;
  v = a[15];
  t15 += v * b0;
  t16 += v * b1;
  t17 += v * b2;
  t18 += v * b3;
  t19 += v * b4;
  t20 += v * b5;
  t21 += v * b6;
  t22 += v * b7;
  t23 += v * b8;
  t24 += v * b9;
  t25 += v * b10;
  t26 += v * b11;
  t27 += v * b12;
  t28 += v * b13;
  t29 += v * b14;
  t30 += v * b15;

  t0  += 38 * t16;
  t1  += 38 * t17;
  t2  += 38 * t18;
  t3  += 38 * t19;
  t4  += 38 * t20;
  t5  += 38 * t21;
  t6  += 38 * t22;
  t7  += 38 * t23;
  t8  += 38 * t24;
  t9  += 38 * t25;
  t10 += 38 * t26;
  t11 += 38 * t27;
  t12 += 38 * t28;
  t13 += 38 * t29;
  t14 += 38 * t30;
  // t15 left as is

  // first car
  c = 1;
  v =  t0 + c + 65535; c = Math.floor(v / 65536);  t0 = v - c * 65536;
  v =  t1 + c + 65535; c = Math.floor(v / 65536);  t1 = v - c * 65536;
  v =  t2 + c + 65535; c = Math.floor(v / 65536);  t2 = v - c * 65536;
  v =  t3 + c + 65535; c = Math.floor(v / 65536);  t3 = v - c * 65536;
  v =  t4 + c + 65535; c = Math.floor(v / 65536);  t4 = v - c * 65536;
  v =  t5 + c + 65535; c = Math.floor(v / 65536);  t5 = v - c * 65536;
  v =  t6 + c + 65535; c = Math.floor(v / 65536);  t6 = v - c * 65536;
  v =  t7 + c + 65535; c = Math.floor(v / 65536);  t7 = v - c * 65536;
  v =  t8 + c + 65535; c = Math.floor(v / 65536);  t8 = v - c * 65536;
  v =  t9 + c + 65535; c = Math.floor(v / 65536);  t9 = v - c * 65536;
  v = t10 + c + 65535; c = Math.floor(v / 65536); t10 = v - c * 65536;
  v = t11 + c + 65535; c = Math.floor(v / 65536); t11 = v - c * 65536;
  v = t12 + c + 65535; c = Math.floor(v / 65536); t12 = v - c * 65536;
  v = t13 + c + 65535; c = Math.floor(v / 65536); t13 = v - c * 65536;
  v = t14 + c + 65535; c = Math.floor(v / 65536); t14 = v - c * 65536;
  v = t15 + c + 65535; c = Math.floor(v / 65536); t15 = v - c * 65536;
  t0 += c-1 + 37 * (c-1);

  // second car
  c = 1;
  v =  t0 + c + 65535; c = Math.floor(v / 65536);  t0 = v - c * 65536;
  v =  t1 + c + 65535; c = Math.floor(v / 65536);  t1 = v - c * 65536;
  v =  t2 + c + 65535; c = Math.floor(v / 65536);  t2 = v - c * 65536;
  v =  t3 + c + 65535; c = Math.floor(v / 65536);  t3 = v - c * 65536;
  v =  t4 + c + 65535; c = Math.floor(v / 65536);  t4 = v - c * 65536;
  v =  t5 + c + 65535; c = Math.floor(v / 65536);  t5 = v - c * 65536;
  v =  t6 + c + 65535; c = Math.floor(v / 65536);  t6 = v - c * 65536;
  v =  t7 + c + 65535; c = Math.floor(v / 65536);  t7 = v - c * 65536;
  v =  t8 + c + 65535; c = Math.floor(v / 65536);  t8 = v - c * 65536;
  v =  t9 + c + 65535; c = Math.floor(v / 65536);  t9 = v - c * 65536;
  v = t10 + c + 65535; c = Math.floor(v / 65536); t10 = v - c * 65536;
  v = t11 + c + 65535; c = Math.floor(v / 65536); t11 = v - c * 65536;
  v = t12 + c + 65535; c = Math.floor(v / 65536); t12 = v - c * 65536;
  v = t13 + c + 65535; c = Math.floor(v / 65536); t13 = v - c * 65536;
  v = t14 + c + 65535; c = Math.floor(v / 65536); t14 = v - c * 65536;
  v = t15 + c + 65535; c = Math.floor(v / 65536); t15 = v - c * 65536;
  t0 += c-1 + 37 * (c-1);

  o[ 0] = t0;
  o[ 1] = t1;
  o[ 2] = t2;
  o[ 3] = t3;
  o[ 4] = t4;
  o[ 5] = t5;
  o[ 6] = t6;
  o[ 7] = t7;
  o[ 8] = t8;
  o[ 9] = t9;
  o[10] = t10;
  o[11] = t11;
  o[12] = t12;
  o[13] = t13;
  o[14] = t14;
  o[15] = t15;
}

function S(o, a) {
  M(o, a, a);
}

function inv25519(o, i) {
  var c = gf();
  var a;
  for (a = 0; a < 16; a++) c[a] = i[a];
  for (a = 253; a >= 0; a--) {
    S(c, c);
    if(a !== 2 && a !== 4) M(c, c, i);
  }
  for (a = 0; a < 16; a++) o[a] = c[a];
}

function pow2523(o, i) {
  var c = gf();
  var a;
  for (a = 0; a < 16; a++) c[a] = i[a];
  for (a = 250; a >= 0; a--) {
      S(c, c);
      if(a !== 1) M(c, c, i);
  }
  for (a = 0; a < 16; a++) o[a] = c[a];
}

function crypto_scalarmult(q, n, p) {
  var z = new Uint8Array(32);
  var x = new Float64Array(80), r, i;
  var a = gf(), b = gf(), c = gf(),
      d = gf(), e = gf(), f = gf();
  for (i = 0; i < 31; i++) z[i] = n[i];
  z[31]=(n[31]&127)|64;
  z[0]&=248;
  unpack25519(x,p);
  for (i = 0; i < 16; i++) {
    b[i]=x[i];
    d[i]=a[i]=c[i]=0;
  }
  a[0]=d[0]=1;
  for (i=254; i>=0; --i) {
    r=(z[i>>>3]>>>(i&7))&1;
    sel25519(a,b,r);
    sel25519(c,d,r);
    A(e,a,c);
    Z(a,a,c);
    A(c,b,d);
    Z(b,b,d);
    S(d,e);
    S(f,a);
    M(a,c,a);
    M(c,b,e);
    A(e,a,c);
    Z(a,a,c);
    S(b,a);
    Z(c,d,f);
    M(a,c,_121665);
    A(a,a,d);
    M(c,c,a);
    M(a,d,f);
    M(d,b,x);
    S(b,e);
    sel25519(a,b,r);
    sel25519(c,d,r);
  }
  for (i = 0; i < 16; i++) {
    x[i+16]=a[i];
    x[i+32]=c[i];
    x[i+48]=b[i];
    x[i+64]=d[i];
  }
  var x32 = x.subarray(32);
  var x16 = x.subarray(16);
  inv25519(x32,x32);
  M(x16,x16,x32);
  pack25519(q,x16);
  return 0;
}

function crypto_scalarmult_base(q, n) {
  return crypto_scalarmult(q, n, _9);
}

async function crypto_box_keypair(y, x) {
  await randombytes(x, 32);
  return crypto_scalarmult_base(y, x);
}

function crypto_box_beforenm(k, y, x) {
  var s = new Uint8Array(32);
  crypto_scalarmult(s, x, y);
  return crypto_core_hsalsa20(k, _0, s, sigma);
}

var crypto_box_afternm = crypto_secretbox;
var crypto_box_open_afternm = crypto_secretbox_open;

function crypto_box(c, m, d, n, y, x) {
  var k = new Uint8Array(32);
  crypto_box_beforenm(k, y, x);
  return crypto_box_afternm(c, m, d, n, k);
}

function crypto_box_open(m, c, d, n, y, x) {
  var k = new Uint8Array(32);
  crypto_box_beforenm(k, y, x);
  return crypto_box_open_afternm(m, c, d, n, k);
}

var K = [
  0x428a2f98, 0xd728ae22, 0x71374491, 0x23ef65cd,
  0xb5c0fbcf, 0xec4d3b2f, 0xe9b5dba5, 0x8189dbbc,
  0x3956c25b, 0xf348b538, 0x59f111f1, 0xb605d019,
  0x923f82a4, 0xaf194f9b, 0xab1c5ed5, 0xda6d8118,
  0xd807aa98, 0xa3030242, 0x12835b01, 0x45706fbe,
  0x243185be, 0x4ee4b28c, 0x550c7dc3, 0xd5ffb4e2,
  0x72be5d74, 0xf27b896f, 0x80deb1fe, 0x3b1696b1,
  0x9bdc06a7, 0x25c71235, 0xc19bf174, 0xcf692694,
  0xe49b69c1, 0x9ef14ad2, 0xefbe4786, 0x384f25e3,
  0x0fc19dc6, 0x8b8cd5b5, 0x240ca1cc, 0x77ac9c65,
  0x2de92c6f, 0x592b0275, 0x4a7484aa, 0x6ea6e483,
  0x5cb0a9dc, 0xbd41fbd4, 0x76f988da, 0x831153b5,
  0x983e5152, 0xee66dfab, 0xa831c66d, 0x2db43210,
  0xb00327c8, 0x98fb213f, 0xbf597fc7, 0xbeef0ee4,
  0xc6e00bf3, 0x3da88fc2, 0xd5a79147, 0x930aa725,
  0x06ca6351, 0xe003826f, 0x14292967, 0x0a0e6e70,
  0x27b70a85, 0x46d22ffc, 0x2e1b2138, 0x5c26c926,
  0x4d2c6dfc, 0x5ac42aed, 0x53380d13, 0x9d95b3df,
  0x650a7354, 0x8baf63de, 0x766a0abb, 0x3c77b2a8,
  0x81c2c92e, 0x47edaee6, 0x92722c85, 0x1482353b,
  0xa2bfe8a1, 0x4cf10364, 0xa81a664b, 0xbc423001,
  0xc24b8b70, 0xd0f89791, 0xc76c51a3, 0x0654be30,
  0xd192e819, 0xd6ef5218, 0xd6990624, 0x5565a910,
  0xf40e3585, 0x5771202a, 0x106aa070, 0x32bbd1b8,
  0x19a4c116, 0xb8d2d0c8, 0x1e376c08, 0x5141ab53,
  0x2748774c, 0xdf8eeb99, 0x34b0bcb5, 0xe19b48a8,
  0x391c0cb3, 0xc5c95a63, 0x4ed8aa4a, 0xe3418acb,
  0x5b9cca4f, 0x7763e373, 0x682e6ff3, 0xd6b2b8a3,
  0x748f82ee, 0x5defb2fc, 0x78a5636f, 0x43172f60,
  0x84c87814, 0xa1f0ab72, 0x8cc70208, 0x1a6439ec,
  0x90befffa, 0x23631e28, 0xa4506ceb, 0xde82bde9,
  0xbef9a3f7, 0xb2c67915, 0xc67178f2, 0xe372532b,
  0xca273ece, 0xea26619c, 0xd186b8c7, 0x21c0c207,
  0xeada7dd6, 0xcde0eb1e, 0xf57d4f7f, 0xee6ed178,
  0x06f067aa, 0x72176fba, 0x0a637dc5, 0xa2c898a6,
  0x113f9804, 0xbef90dae, 0x1b710b35, 0x131c471b,
  0x28db77f5, 0x23047d84, 0x32caab7b, 0x40c72493,
  0x3c9ebe0a, 0x15c9bebc, 0x431d67c4, 0x9c100d4c,
  0x4cc5d4be, 0xcb3e42b6, 0x597f299c, 0xfc657e2a,
  0x5fcb6fab, 0x3ad6faec, 0x6c44198c, 0x4a475817
];

function crypto_hashblocks_hl(hh, hl, m, n) {
  var wh = new Int32Array(16), wl = new Int32Array(16),
      bh0, bh1, bh2, bh3, bh4, bh5, bh6, bh7,
      bl0, bl1, bl2, bl3, bl4, bl5, bl6, bl7,
      th, tl, i, j, h, l, a, b, c, d;

  var ah0 = hh[0],
      ah1 = hh[1],
      ah2 = hh[2],
      ah3 = hh[3],
      ah4 = hh[4],
      ah5 = hh[5],
      ah6 = hh[6],
      ah7 = hh[7],

      al0 = hl[0],
      al1 = hl[1],
      al2 = hl[2],
      al3 = hl[3],
      al4 = hl[4],
      al5 = hl[5],
      al6 = hl[6],
      al7 = hl[7];

  var pos = 0;
  while (n >= 128) {
    for (i = 0; i < 16; i++) {
      j = 8 * i + pos;
      wh[i] = (m[j+0] << 24) | (m[j+1] << 16) | (m[j+2] << 8) | m[j+3];
      wl[i] = (m[j+4] << 24) | (m[j+5] << 16) | (m[j+6] << 8) | m[j+7];
    }
    for (i = 0; i < 80; i++) {
      bh0 = ah0;
      bh1 = ah1;
      bh2 = ah2;
      bh3 = ah3;
      bh4 = ah4;
      bh5 = ah5;
      bh6 = ah6;
      bh7 = ah7;

      bl0 = al0;
      bl1 = al1;
      bl2 = al2;
      bl3 = al3;
      bl4 = al4;
      bl5 = al5;
      bl6 = al6;
      bl7 = al7;

      // add
      h = ah7;
      l = al7;

      a = l & 0xffff; b = l >>> 16;
      c = h & 0xffff; d = h >>> 16;

      // Sigma1
      h = ((ah4 >>> 14) | (al4 << (32-14))) ^ ((ah4 >>> 18) | (al4 << (32-18))) ^ ((al4 >>> (41-32)) | (ah4 << (32-(41-32))));
      l = ((al4 >>> 14) | (ah4 << (32-14))) ^ ((al4 >>> 18) | (ah4 << (32-18))) ^ ((ah4 >>> (41-32)) | (al4 << (32-(41-32))));

      a += l & 0xffff; b += l >>> 16;
      c += h & 0xffff; d += h >>> 16;

      // Ch
      h = (ah4 & ah5) ^ (~ah4 & ah6);
      l = (al4 & al5) ^ (~al4 & al6);

      a += l & 0xffff; b += l >>> 16;
      c += h & 0xffff; d += h >>> 16;

      // K
      h = K[i*2];
      l = K[i*2+1];

      a += l & 0xffff; b += l >>> 16;
      c += h & 0xffff; d += h >>> 16;

      // w
      h = wh[i%16];
      l = wl[i%16];

      a += l & 0xffff; b += l >>> 16;
      c += h & 0xffff; d += h >>> 16;

      b += a >>> 16;
      c += b >>> 16;
      d += c >>> 16;

      th = c & 0xffff | d << 16;
      tl = a & 0xffff | b << 16;

      // add
      h = th;
      l = tl;

      a = l & 0xffff; b = l >>> 16;
      c = h & 0xffff; d = h >>> 16;

      // Sigma0
      h = ((ah0 >>> 28) | (al0 << (32-28))) ^ ((al0 >>> (34-32)) | (ah0 << (32-(34-32)))) ^ ((al0 >>> (39-32)) | (ah0 << (32-(39-32))));
      l = ((al0 >>> 28) | (ah0 << (32-28))) ^ ((ah0 >>> (34-32)) | (al0 << (32-(34-32)))) ^ ((ah0 >>> (39-32)) | (al0 << (32-(39-32))));

      a += l & 0xffff; b += l >>> 16;
      c += h & 0xffff; d += h >>> 16;

      // Maj
      h = (ah0 & ah1) ^ (ah0 & ah2) ^ (ah1 & ah2);
      l = (al0 & al1) ^ (al0 & al2) ^ (al1 & al2);

      a += l & 0xffff; b += l >>> 16;
      c += h & 0xffff; d += h >>> 16;

      b += a >>> 16;
      c += b >>> 16;
      d += c >>> 16;

      bh7 = (c & 0xffff) | (d << 16);
      bl7 = (a & 0xffff) | (b << 16);

      // add
      h = bh3;
      l = bl3;

      a = l & 0xffff; b = l >>> 16;
      c = h & 0xffff; d = h >>> 16;

      h = th;
      l = tl;

      a += l & 0xffff; b += l >>> 16;
      c += h & 0xffff; d += h >>> 16;

      b += a >>> 16;
      c += b >>> 16;
      d += c >>> 16;

      bh3 = (c & 0xffff) | (d << 16);
      bl3 = (a & 0xffff) | (b << 16);

      ah1 = bh0;
      ah2 = bh1;
      ah3 = bh2;
      ah4 = bh3;
      ah5 = bh4;
      ah6 = bh5;
      ah7 = bh6;
      ah0 = bh7;

      al1 = bl0;
      al2 = bl1;
      al3 = bl2;
      al4 = bl3;
      al5 = bl4;
      al6 = bl5;
      al7 = bl6;
      al0 = bl7;

      if (i%16 === 15) {
        for (j = 0; j < 16; j++) {
          // add
          h = wh[j];
          l = wl[j];

          a = l & 0xffff; b = l >>> 16;
          c = h & 0xffff; d = h >>> 16;

          h = wh[(j+9)%16];
          l = wl[(j+9)%16];

          a += l & 0xffff; b += l >>> 16;
          c += h & 0xffff; d += h >>> 16;

          // sigma0
          th = wh[(j+1)%16];
          tl = wl[(j+1)%16];
          h = ((th >>> 1) | (tl << (32-1))) ^ ((th >>> 8) | (tl << (32-8))) ^ (th >>> 7);
          l = ((tl >>> 1) | (th << (32-1))) ^ ((tl >>> 8) | (th << (32-8))) ^ ((tl >>> 7) | (th << (32-7)));

          a += l & 0xffff; b += l >>> 16;
          c += h & 0xffff; d += h >>> 16;

          // sigma1
          th = wh[(j+14)%16];
          tl = wl[(j+14)%16];
          h = ((th >>> 19) | (tl << (32-19))) ^ ((tl >>> (61-32)) | (th << (32-(61-32)))) ^ (th >>> 6);
          l = ((tl >>> 19) | (th << (32-19))) ^ ((th >>> (61-32)) | (tl << (32-(61-32)))) ^ ((tl >>> 6) | (th << (32-6)));

          a += l & 0xffff; b += l >>> 16;
          c += h & 0xffff; d += h >>> 16;

          b += a >>> 16;
          c += b >>> 16;
          d += c >>> 16;

          wh[j] = (c & 0xffff) | (d << 16);
          wl[j] = (a & 0xffff) | (b << 16);
        }
      }
    }

    // add
    h = ah0;
    l = al0;

    a = l & 0xffff; b = l >>> 16;
    c = h & 0xffff; d = h >>> 16;

    h = hh[0];
    l = hl[0];

    a += l & 0xffff; b += l >>> 16;
    c += h & 0xffff; d += h >>> 16;

    b += a >>> 16;
    c += b >>> 16;
    d += c >>> 16;

    hh[0] = ah0 = (c & 0xffff) | (d << 16);
    hl[0] = al0 = (a & 0xffff) | (b << 16);

    h = ah1;
    l = al1;

    a = l & 0xffff; b = l >>> 16;
    c = h & 0xffff; d = h >>> 16;

    h = hh[1];
    l = hl[1];

    a += l & 0xffff; b += l >>> 16;
    c += h & 0xffff; d += h >>> 16;

    b += a >>> 16;
    c += b >>> 16;
    d += c >>> 16;

    hh[1] = ah1 = (c & 0xffff) | (d << 16);
    hl[1] = al1 = (a & 0xffff) | (b << 16);

    h = ah2;
    l = al2;

    a = l & 0xffff; b = l >>> 16;
    c = h & 0xffff; d = h >>> 16;

    h = hh[2];
    l = hl[2];

    a += l & 0xffff; b += l >>> 16;
    c += h & 0xffff; d += h >>> 16;

    b += a >>> 16;
    c += b >>> 16;
    d += c >>> 16;

    hh[2] = ah2 = (c & 0xffff) | (d << 16);
    hl[2] = al2 = (a & 0xffff) | (b << 16);

    h = ah3;
    l = al3;

    a = l & 0xffff; b = l >>> 16;
    c = h & 0xffff; d = h >>> 16;

    h = hh[3];
    l = hl[3];

    a += l & 0xffff; b += l >>> 16;
    c += h & 0xffff; d += h >>> 16;

    b += a >>> 16;
    c += b >>> 16;
    d += c >>> 16;

    hh[3] = ah3 = (c & 0xffff) | (d << 16);
    hl[3] = al3 = (a & 0xffff) | (b << 16);

    h = ah4;
    l = al4;

    a = l & 0xffff; b = l >>> 16;
    c = h & 0xffff; d = h >>> 16;

    h = hh[4];
    l = hl[4];

    a += l & 0xffff; b += l >>> 16;
    c += h & 0xffff; d += h >>> 16;

    b += a >>> 16;
    c += b >>> 16;
    d += c >>> 16;

    hh[4] = ah4 = (c & 0xffff) | (d << 16);
    hl[4] = al4 = (a & 0xffff) | (b << 16);

    h = ah5;
    l = al5;

    a = l & 0xffff; b = l >>> 16;
    c = h & 0xffff; d = h >>> 16;

    h = hh[5];
    l = hl[5];

    a += l & 0xffff; b += l >>> 16;
    c += h & 0xffff; d += h >>> 16;

    b += a >>> 16;
    c += b >>> 16;
    d += c >>> 16;

    hh[5] = ah5 = (c & 0xffff) | (d << 16);
    hl[5] = al5 = (a & 0xffff) | (b << 16);

    h = ah6;
    l = al6;

    a = l & 0xffff; b = l >>> 16;
    c = h & 0xffff; d = h >>> 16;

    h = hh[6];
    l = hl[6];

    a += l & 0xffff; b += l >>> 16;
    c += h & 0xffff; d += h >>> 16;

    b += a >>> 16;
    c += b >>> 16;
    d += c >>> 16;

    hh[6] = ah6 = (c & 0xffff) | (d << 16);
    hl[6] = al6 = (a & 0xffff) | (b << 16);

    h = ah7;
    l = al7;

    a = l & 0xffff; b = l >>> 16;
    c = h & 0xffff; d = h >>> 16;

    h = hh[7];
    l = hl[7];

    a += l & 0xffff; b += l >>> 16;
    c += h & 0xffff; d += h >>> 16;

    b += a >>> 16;
    c += b >>> 16;
    d += c >>> 16;

    hh[7] = ah7 = (c & 0xffff) | (d << 16);
    hl[7] = al7 = (a & 0xffff) | (b << 16);

    pos += 128;
    n -= 128;
  }

  return n;
}

function crypto_hash(out, m, n) {
  var hh = new Int32Array(8),
      hl = new Int32Array(8),
      x = new Uint8Array(256),
      i, b = n;

  hh[0] = 0x6a09e667;
  hh[1] = 0xbb67ae85;
  hh[2] = 0x3c6ef372;
  hh[3] = 0xa54ff53a;
  hh[4] = 0x510e527f;
  hh[5] = 0x9b05688c;
  hh[6] = 0x1f83d9ab;
  hh[7] = 0x5be0cd19;

  hl[0] = 0xf3bcc908;
  hl[1] = 0x84caa73b;
  hl[2] = 0xfe94f82b;
  hl[3] = 0x5f1d36f1;
  hl[4] = 0xade682d1;
  hl[5] = 0x2b3e6c1f;
  hl[6] = 0xfb41bd6b;
  hl[7] = 0x137e2179;

  crypto_hashblocks_hl(hh, hl, m, n);
  n %= 128;

  for (i = 0; i < n; i++) x[i] = m[b-n+i];
  x[n] = 128;

  n = 256-128*(n<112?1:0);
  x[n-9] = 0;
  ts64(x, n-8,  (b / 0x20000000) | 0, b << 3);
  crypto_hashblocks_hl(hh, hl, x, n);

  for (i = 0; i < 8; i++) ts64(out, 8*i, hh[i], hl[i]);

  return 0;
}

function add(p, q) {
  var a = gf(), b = gf(), c = gf(),
      d = gf(), e = gf(), f = gf(),
      g = gf(), h = gf(), t = gf();

  Z(a, p[1], p[0]);
  Z(t, q[1], q[0]);
  M(a, a, t);
  A(b, p[0], p[1]);
  A(t, q[0], q[1]);
  M(b, b, t);
  M(c, p[3], q[3]);
  M(c, c, D2);
  M(d, p[2], q[2]);
  A(d, d, d);
  Z(e, b, a);
  Z(f, d, c);
  A(g, d, c);
  A(h, b, a);

  M(p[0], e, f);
  M(p[1], h, g);
  M(p[2], g, f);
  M(p[3], e, h);
}

function cswap(p, q, b) {
  var i;
  for (i = 0; i < 4; i++) {
    sel25519(p[i], q[i], b);
  }
}

function pack(r, p) {
  var tx = gf(), ty = gf(), zi = gf();
  inv25519(zi, p[2]);
  M(tx, p[0], zi);
  M(ty, p[1], zi);
  pack25519(r, ty);
  r[31] ^= par25519(tx) << 7;
}

function scalarmult(p, q, s) {
  var b, i;
  set25519(p[0], gf0);
  set25519(p[1], gf1);
  set25519(p[2], gf1);
  set25519(p[3], gf0);
  for (i = 255; i >= 0; --i) {
    b = (s[(i/8)|0] >> (i&7)) & 1;
    cswap(p, q, b);
    add(q, p);
    add(p, p);
    cswap(p, q, b);
  }
}

function scalarbase(p, s) {
  var q = [gf(), gf(), gf(), gf()];
  set25519(q[0], X);
  set25519(q[1], Y);
  set25519(q[2], gf1);
  M(q[3], X, Y);
  scalarmult(p, q, s);
}

async function crypto_sign_keypair(pk, sk, seeded) {
  var d = new Uint8Array(64);
  var p = [gf(), gf(), gf(), gf()];
  var i;

  if (!seeded) await randombytes(sk, 32);
  crypto_hash(d, sk, 32);
  d[0] &= 248;
  d[31] &= 127;
  d[31] |= 64;

  scalarbase(p, d);
  pack(pk, p);

  for (i = 0; i < 32; i++) sk[i+32] = pk[i];
  return 0;
}

var L = new Float64Array([0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58, 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x10]);

function modL(r, x) {
  var carry, i, j, k;
  for (i = 63; i >= 32; --i) {
    carry = 0;
    for (j = i - 32, k = i - 12; j < k; ++j) {
      x[j] += carry - 16 * x[i] * L[j - (i - 32)];
      carry = (x[j] + 128) >> 8;
      x[j] -= carry * 256;
    }
    x[j] += carry;
    x[i] = 0;
  }
  carry = 0;
  for (j = 0; j < 32; j++) {
    x[j] += carry - (x[31] >> 4) * L[j];
    carry = x[j] >> 8;
    x[j] &= 255;
  }
  for (j = 0; j < 32; j++) x[j] -= carry * L[j];
  for (i = 0; i < 32; i++) {
    x[i+1] += x[i] >> 8;
    r[i] = x[i] & 255;
  }
}

function reduce(r) {
  var x = new Float64Array(64), i;
  for (i = 0; i < 64; i++) x[i] = r[i];
  for (i = 0; i < 64; i++) r[i] = 0;
  modL(r, x);
}

// Note: difference from C - smlen returned, not passed as argument.
function crypto_sign(sm, m, n, sk) {
  var d = new Uint8Array(64), h = new Uint8Array(64), r = new Uint8Array(64);
  var i, j, x = new Float64Array(64);
  var p = [gf(), gf(), gf(), gf()];

  crypto_hash(d, sk, 32);
  d[0] &= 248;
  d[31] &= 127;
  d[31] |= 64;

  var smlen = n + 64;
  for (i = 0; i < n; i++) sm[64 + i] = m[i];
  for (i = 0; i < 32; i++) sm[32 + i] = d[32 + i];

  crypto_hash(r, sm.subarray(32), n+32);
  reduce(r);
  scalarbase(p, r);
  pack(sm, p);

  for (i = 32; i < 64; i++) sm[i] = sk[i];
  crypto_hash(h, sm, n + 64);
  reduce(h);

  for (i = 0; i < 64; i++) x[i] = 0;
  for (i = 0; i < 32; i++) x[i] = r[i];
  for (i = 0; i < 32; i++) {
    for (j = 0; j < 32; j++) {
      x[i+j] += h[i] * d[j];
    }
  }

  modL(sm.subarray(32), x);
  return smlen;
}

function unpackneg(r, p) {
  var t = gf(), chk = gf(), num = gf(),
      den = gf(), den2 = gf(), den4 = gf(),
      den6 = gf();

  set25519(r[2], gf1);
  unpack25519(r[1], p);
  S(num, r[1]);
  M(den, num, D);
  Z(num, num, r[2]);
  A(den, r[2], den);

  S(den2, den);
  S(den4, den2);
  M(den6, den4, den2);
  M(t, den6, num);
  M(t, t, den);

  pow2523(t, t);
  M(t, t, num);
  M(t, t, den);
  M(t, t, den);
  M(r[0], t, den);

  S(chk, r[0]);
  M(chk, chk, den);
  if (neq25519(chk, num)) M(r[0], r[0], I);

  S(chk, r[0]);
  M(chk, chk, den);
  if (neq25519(chk, num)) return -1;

  if (par25519(r[0]) === (p[31]>>7)) Z(r[0], gf0, r[0]);

  M(r[3], r[0], r[1]);
  return 0;
}

function crypto_sign_open(m, sm, n, pk) {
  var i, mlen;
  var t = new Uint8Array(32), h = new Uint8Array(64);
  var p = [gf(), gf(), gf(), gf()],
      q = [gf(), gf(), gf(), gf()];

  mlen = -1;
  if (n < 64) return -1;

  if (unpackneg(q, pk)) return -1;

  for (i = 0; i < n; i++) m[i] = sm[i];
  for (i = 0; i < 32; i++) m[i+32] = pk[i];
  crypto_hash(h, m, n);
  reduce(h);
  scalarmult(p, q, h);

  scalarbase(q, sm.subarray(32));
  add(p, q);
  pack(t, p);

  n -= 64;
  if (crypto_verify_32(sm, 0, t, 0)) {
    for (i = 0; i < n; i++) m[i] = 0;
    return -1;
  }

  for (i = 0; i < n; i++) m[i] = sm[i + 64];
  mlen = n;
  return mlen;
}

var crypto_secretbox_KEYBYTES = 32,
    crypto_secretbox_NONCEBYTES = 24,
    crypto_secretbox_ZEROBYTES = 32,
    crypto_secretbox_BOXZEROBYTES = 16,
    crypto_scalarmult_BYTES = 32,
    crypto_scalarmult_SCALARBYTES = 32,
    crypto_box_PUBLICKEYBYTES = 32,
    crypto_box_SECRETKEYBYTES = 32,
    crypto_box_BEFORENMBYTES = 32,
    crypto_box_NONCEBYTES = crypto_secretbox_NONCEBYTES,
    crypto_box_ZEROBYTES = crypto_secretbox_ZEROBYTES,
    crypto_box_BOXZEROBYTES = crypto_secretbox_BOXZEROBYTES,
    crypto_sign_BYTES = 64,
    crypto_sign_PUBLICKEYBYTES = 32,
    crypto_sign_SECRETKEYBYTES = 64,
    crypto_sign_SEEDBYTES = 32,
    crypto_hash_BYTES = 64;

nacl.lowlevel = {
  crypto_core_hsalsa20: crypto_core_hsalsa20,
  crypto_stream_xor: crypto_stream_xor,
  crypto_stream: crypto_stream,
  crypto_stream_salsa20_xor: crypto_stream_salsa20_xor,
  crypto_stream_salsa20: crypto_stream_salsa20,
  crypto_onetimeauth: crypto_onetimeauth,
  crypto_onetimeauth_verify: crypto_onetimeauth_verify,
  crypto_verify_16: crypto_verify_16,
  crypto_verify_32: crypto_verify_32,
  crypto_secretbox: crypto_secretbox,
  crypto_secretbox_open: crypto_secretbox_open,
  crypto_scalarmult: crypto_scalarmult,
  crypto_scalarmult_base: crypto_scalarmult_base,
  crypto_box_beforenm: crypto_box_beforenm,
  crypto_box_afternm: crypto_box_afternm,
  crypto_box: crypto_box,
  crypto_box_open: crypto_box_open,
  crypto_box_keypair: crypto_box_keypair,
  crypto_hash: crypto_hash,
  crypto_sign: crypto_sign,
  crypto_sign_keypair: crypto_sign_keypair,
  crypto_sign_open: crypto_sign_open,

  crypto_secretbox_KEYBYTES: crypto_secretbox_KEYBYTES,
  crypto_secretbox_NONCEBYTES: crypto_secretbox_NONCEBYTES,
  crypto_secretbox_ZEROBYTES: crypto_secretbox_ZEROBYTES,
  crypto_secretbox_BOXZEROBYTES: crypto_secretbox_BOXZEROBYTES,
  crypto_scalarmult_BYTES: crypto_scalarmult_BYTES,
  crypto_scalarmult_SCALARBYTES: crypto_scalarmult_SCALARBYTES,
  crypto_box_PUBLICKEYBYTES: crypto_box_PUBLICKEYBYTES,
  crypto_box_SECRETKEYBYTES: crypto_box_SECRETKEYBYTES,
  crypto_box_BEFORENMBYTES: crypto_box_BEFORENMBYTES,
  crypto_box_NONCEBYTES: crypto_box_NONCEBYTES,
  crypto_box_ZEROBYTES: crypto_box_ZEROBYTES,
  crypto_box_BOXZEROBYTES: crypto_box_BOXZEROBYTES,
  crypto_sign_BYTES: crypto_sign_BYTES,
  crypto_sign_PUBLICKEYBYTES: crypto_sign_PUBLICKEYBYTES,
  crypto_sign_SECRETKEYBYTES: crypto_sign_SECRETKEYBYTES,
  crypto_sign_SEEDBYTES: crypto_sign_SEEDBYTES,
  crypto_hash_BYTES: crypto_hash_BYTES
};

/* High-level API */

function checkLengths(k, n) {
  if (k.length !== crypto_secretbox_KEYBYTES) throw new Error('bad key size');
  if (n.length !== crypto_secretbox_NONCEBYTES) throw new Error('bad nonce size');
}

function checkBoxLengths(pk, sk) {
  if (pk.length !== crypto_box_PUBLICKEYBYTES) throw new Error('bad public key size');
  if (sk.length !== crypto_box_SECRETKEYBYTES) throw new Error('bad secret key size');
}

function checkArrayTypes() {
  for (var i = 0; i < arguments.length; i++) {
    if (!(arguments[i] instanceof Uint8Array))
      throw new TypeError('unexpected type, use Uint8Array');
  }
}

function cleanup(arr) {
  for (var i = 0; i < arr.length; i++) arr[i] = 0;
}

nacl.randomBytes = async function(n) {
  var b = new Uint8Array(n);
  await randombytes(b, n);
  return b;
};

nacl.secretbox = function(msg, nonce, key) {
  checkArrayTypes(msg, nonce, key);
  checkLengths(key, nonce);
  var m = new Uint8Array(crypto_secretbox_ZEROBYTES + msg.length);
  var c = new Uint8Array(m.length);
  for (var i = 0; i < msg.length; i++) m[i+crypto_secretbox_ZEROBYTES] = msg[i];
  crypto_secretbox(c, m, m.length, nonce, key);
  return c.subarray(crypto_secretbox_BOXZEROBYTES);
};

nacl.secretbox.open = function(box, nonce, key) {
  checkArrayTypes(box, nonce, key);
  checkLengths(key, nonce);
  var c = new Uint8Array(crypto_secretbox_BOXZEROBYTES + box.length);
  var m = new Uint8Array(c.length);
  for (var i = 0; i < box.length; i++) c[i+crypto_secretbox_BOXZEROBYTES] = box[i];
  if (c.length < 32) return null;
  if (crypto_secretbox_open(m, c, c.length, nonce, key) !== 0) return null;
  return m.subarray(crypto_secretbox_ZEROBYTES);
};

nacl.secretbox.keyLength = crypto_secretbox_KEYBYTES;
nacl.secretbox.nonceLength = crypto_secretbox_NONCEBYTES;
nacl.secretbox.overheadLength = crypto_secretbox_BOXZEROBYTES;

nacl.scalarMult = function(n, p) {
  checkArrayTypes(n, p);
  if (n.length !== crypto_scalarmult_SCALARBYTES) throw new Error('bad n size');
  if (p.length !== crypto_scalarmult_BYTES) throw new Error('bad p size');
  var q = new Uint8Array(crypto_scalarmult_BYTES);
  crypto_scalarmult(q, n, p);
  return q;
};

nacl.scalarMult.base = function(n) {
  checkArrayTypes(n);
  if (n.length !== crypto_scalarmult_SCALARBYTES) throw new Error('bad n size');
  var q = new Uint8Array(crypto_scalarmult_BYTES);
  crypto_scalarmult_base(q, n);
  return q;
};

nacl.scalarMult.scalarLength = crypto_scalarmult_SCALARBYTES;
nacl.scalarMult.groupElementLength = crypto_scalarmult_BYTES;

nacl.box = function(msg, nonce, publicKey, secretKey) {
  var k = nacl.box.before(publicKey, secretKey);
  return nacl.secretbox(msg, nonce, k);
};

nacl.box.before = function(publicKey, secretKey) {
  checkArrayTypes(publicKey, secretKey);
  checkBoxLengths(publicKey, secretKey);
  var k = new Uint8Array(crypto_box_BEFORENMBYTES);
  crypto_box_beforenm(k, publicKey, secretKey);
  return k;
};

nacl.box.after = nacl.secretbox;

nacl.box.open = function(msg, nonce, publicKey, secretKey) {
  var k = nacl.box.before(publicKey, secretKey);
  return nacl.secretbox.open(msg, nonce, k);
};

nacl.box.open.after = nacl.secretbox.open;

nacl.box.keyPair = async function() {
  var pk = new Uint8Array(crypto_box_PUBLICKEYBYTES);
  var sk = new Uint8Array(crypto_box_SECRETKEYBYTES);
  await crypto_box_keypair(pk, sk);
  return {publicKey: pk, secretKey: sk};
};

nacl.box.keyPair.fromSecretKey = function(secretKey) {
  checkArrayTypes(secretKey);
  if (secretKey.length !== crypto_box_SECRETKEYBYTES)
    throw new Error('bad secret key size');
  var pk = new Uint8Array(crypto_box_PUBLICKEYBYTES);
  crypto_scalarmult_base(pk, secretKey);
  return {publicKey: pk, secretKey: new Uint8Array(secretKey)};
};

nacl.box.publicKeyLength = crypto_box_PUBLICKEYBYTES;
nacl.box.secretKeyLength = crypto_box_SECRETKEYBYTES;
nacl.box.sharedKeyLength = crypto_box_BEFORENMBYTES;
nacl.box.nonceLength = crypto_box_NONCEBYTES;
nacl.box.overheadLength = nacl.secretbox.overheadLength;

nacl.sign = function(msg, secretKey) {
  checkArrayTypes(msg, secretKey);
  if (secretKey.length !== crypto_sign_SECRETKEYBYTES)
    throw new Error('bad secret key size');
  var signedMsg = new Uint8Array(crypto_sign_BYTES+msg.length);
  crypto_sign(signedMsg, msg, msg.length, secretKey);
  return signedMsg;
};

nacl.sign.open = function(signedMsg, publicKey) {
  checkArrayTypes(signedMsg, publicKey);
  if (publicKey.length !== crypto_sign_PUBLICKEYBYTES)
    throw new Error('bad public key size');
  var tmp = new Uint8Array(signedMsg.length);
  var mlen = crypto_sign_open(tmp, signedMsg, signedMsg.length, publicKey);
  if (mlen < 0) return null;
  var m = new Uint8Array(mlen);
  for (var i = 0; i < m.length; i++) m[i] = tmp[i];
  return m;
};

nacl.sign.detached = function(msg, secretKey) {
  var signedMsg = nacl.sign(msg, secretKey);
  var sig = new Uint8Array(crypto_sign_BYTES);
  for (var i = 0; i < sig.length; i++) sig[i] = signedMsg[i];
  return sig;
};

nacl.sign.detached.verify = function(msg, sig, publicKey) {
  checkArrayTypes(msg, sig, publicKey);
  if (sig.length !== crypto_sign_BYTES)
    throw new Error('bad signature size');
  if (publicKey.length !== crypto_sign_PUBLICKEYBYTES)
    throw new Error('bad public key size');
  var sm = new Uint8Array(crypto_sign_BYTES + msg.length);
  var m = new Uint8Array(crypto_sign_BYTES + msg.length);
  var i;
  for (i = 0; i < crypto_sign_BYTES; i++) sm[i] = sig[i];
  for (i = 0; i < msg.length; i++) sm[i+crypto_sign_BYTES] = msg[i];
  return (crypto_sign_open(m, sm, sm.length, publicKey) >= 0);
};

nacl.sign.keyPair = async function() {
  var pk = new Uint8Array(crypto_sign_PUBLICKEYBYTES);
  var sk = new Uint8Array(crypto_sign_SECRETKEYBYTES);
  await crypto_sign_keypair(pk, sk);
  return {publicKey: pk, secretKey: sk};
};

nacl.sign.keyPair.fromSecretKey = function(secretKey) {
  checkArrayTypes(secretKey);
  if (secretKey.length !== crypto_sign_SECRETKEYBYTES)
    throw new Error('bad secret key size');
  var pk = new Uint8Array(crypto_sign_PUBLICKEYBYTES);
  for (var i = 0; i < pk.length; i++) pk[i] = secretKey[32+i];
  return {publicKey: pk, secretKey: new Uint8Array(secretKey)};
};

nacl.sign.keyPair.fromSeed = async function(seed) {
  checkArrayTypes(seed);
  if (seed.length !== crypto_sign_SEEDBYTES)
    throw new Error('bad seed size');
  var pk = new Uint8Array(crypto_sign_PUBLICKEYBYTES);
  var sk = new Uint8Array(crypto_sign_SECRETKEYBYTES);
  for (var i = 0; i < 32; i++) sk[i] = seed[i];
  await crypto_sign_keypair(pk, sk, true);
  return {publicKey: pk, secretKey: sk};
};

nacl.sign.publicKeyLength = crypto_sign_PUBLICKEYBYTES;
nacl.sign.secretKeyLength = crypto_sign_SECRETKEYBYTES;
nacl.sign.seedLength = crypto_sign_SEEDBYTES;
nacl.sign.signatureLength = crypto_sign_BYTES;

nacl.hash = function(msg) {
  checkArrayTypes(msg);
  var h = new Uint8Array(crypto_hash_BYTES);
  crypto_hash(h, msg, msg.length);
  return h;
};

nacl.hash.hashLength = crypto_hash_BYTES;

nacl.verify = function(x, y) {
  checkArrayTypes(x, y);
  // Zero length arguments are considered not equal.
  if (x.length === 0 || y.length === 0) return false;
  if (x.length !== y.length) return false;
  return (vn(x, 0, y, 0, x.length) === 0) ? true : false;
};

nacl.setPRNG = function(fn) {
  randombytes = fn;
};

(function() {
  // initialize PRNG as a function to use getRandomBytes

  nacl.setPRNG(async function(x, n) {
    var i, v = await getRandomBytesAsync(n);
    for (i = 0; i < n; i++) x[i] = v[i];
    cleanup(v);
  });
})();

})(typeof module !== 'undefined' && module.exports ? module.exports : (self.nacl = self.nacl || {}));