// http://bitwiseshiftleft.github.io/sjcl/
// ./configure --without-all --with-sha256 --with-sha512 --with-sha1 --with-hmac --with-codecBase64 --with-codecString --with-aes --with-ccm --with-convenience --compress=none
// Copyright 2009-2010 Emily Stark, Mike Hamburg, Dan Boneh, Stanford University.
// SJCL is dual-licensed under the GNU GPL version 2.0 or higher, and a 2-clause BSD license.

/** @fileOverview Javascript cryptography implementation.
 *
 * Crush to remove comments, shorten variable names and
 * generally reduce transmission size.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

"use strict";
/*jslint indent: 2, bitwise: false, nomen: false, plusplus: false, white: false, regexp: false */
/*global document, window, escape, unescape, module, require, Uint32Array */

/** @namespace The Stanford Javascript Crypto Library, top-level namespace. */
var sjcl = {
  /** @namespace Symmetric ciphers. */
  cipher: {},

  /** @namespace Hash functions.  Right now only SHA256 is implemented. */
  hash: {},

  /** @namespace Key exchange functions.  Right now only SRP is implemented. */
  keyexchange: {},
  
  /** @namespace Block cipher modes of operation. */
  mode: {},

  /** @namespace Miscellaneous.  HMAC and PBKDF2. */
  misc: {},
  
  /**
   * @namespace Bit array encoders and decoders.
   *
   * @description
   * The members of this namespace are functions which translate between
   * SJCL's bitArrays and other objects (usually strings).  Because it
   * isn't always clear which direction is encoding and which is decoding,
   * the method names are "fromBits" and "toBits".
   */
  codec: {},
  
  /** @namespace Exceptions. */
  exception: {
    /** @constructor Ciphertext is corrupt. */
    corrupt: function(message) {
      this.toString = function() { return "CORRUPT: "+this.message; };
      this.message = message;
    },
    
    /** @constructor Invalid parameter. */
    invalid: function(message) {
      this.toString = function() { return "INVALID: "+this.message; };
      this.message = message;
    },
    
    /** @constructor Bug or missing feature in SJCL. @constructor */
    bug: function(message) {
      this.toString = function() { return "BUG: "+this.message; };
      this.message = message;
    },

    /** @constructor Something isn't ready. */
    notReady: function(message) {
      this.toString = function() { return "NOT READY: "+this.message; };
      this.message = message;
    }
  }
};

if(typeof module !== 'undefined' && module.exports){
  module.exports = sjcl;
}
/** @fileOverview Low-level AES implementation.
 *
 * This file contains a low-level implementation of AES, optimized for
 * size and for efficiency on several browsers.  It is based on
 * OpenSSL's aes_core.c, a public-domain implementation by Vincent
 * Rijmen, Antoon Bosselaers and Paulo Barreto.
 *
 * An older version of this implementation is available in the public
 * domain, but this one is (c) Emily Stark, Mike Hamburg, Dan Boneh,
 * Stanford University 2008-2010 and BSD-licensed for liability
 * reasons.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

/**
 * Schedule out an AES key for both encryption and decryption.  This
 * is a low-level class.  Use a cipher mode to do bulk encryption.
 *
 * @constructor
 * @param {Array} key The key as an array of 4, 6 or 8 words.
 *
 * @class Advanced Encryption Standard (low-level interface)
 */
sjcl.cipher.aes = function (key) {
  if (!this._tables[0][0][0]) {
    this._precompute();
  }
  
  var i, j, tmp,
    encKey, decKey,
    sbox = this._tables[0][4], decTable = this._tables[1],
    keyLen = key.length, rcon = 1;
  
  if (keyLen !== 4 && keyLen !== 6 && keyLen !== 8) {
    throw new sjcl.exception.invalid("invalid aes key size");
  }
  
  this._key = [encKey = key.slice(0), decKey = []];
  
  // schedule encryption keys
  for (i = keyLen; i < 4 * keyLen + 28; i++) {
    tmp = encKey[i-1];
    
    // apply sbox
    if (i%keyLen === 0 || (keyLen === 8 && i%keyLen === 4)) {
      tmp = sbox[tmp>>>24]<<24 ^ sbox[tmp>>16&255]<<16 ^ sbox[tmp>>8&255]<<8 ^ sbox[tmp&255];
      
      // shift rows and add rcon
      if (i%keyLen === 0) {
        tmp = tmp<<8 ^ tmp>>>24 ^ rcon<<24;
        rcon = rcon<<1 ^ (rcon>>7)*283;
      }
    }
    
    encKey[i] = encKey[i-keyLen] ^ tmp;
  }
  
  // schedule decryption keys
  for (j = 0; i; j++, i--) {
    tmp = encKey[j&3 ? i : i - 4];
    if (i<=4 || j<4) {
      decKey[j] = tmp;
    } else {
      decKey[j] = decTable[0][sbox[tmp>>>24      ]] ^
                  decTable[1][sbox[tmp>>16  & 255]] ^
                  decTable[2][sbox[tmp>>8   & 255]] ^
                  decTable[3][sbox[tmp      & 255]];
    }
  }
};

sjcl.cipher.aes.prototype = {
  // public
  /* Something like this might appear here eventually
  name: "AES",
  blockSize: 4,
  keySizes: [4,6,8],
  */
  
  /**
   * Encrypt an array of 4 big-endian words.
   * @param {Array} data The plaintext.
   * @return {Array} The ciphertext.
   */
  encrypt:function (data) { return this._crypt(data,0); },
  
  /**
   * Decrypt an array of 4 big-endian words.
   * @param {Array} data The ciphertext.
   * @return {Array} The plaintext.
   */
  decrypt:function (data) { return this._crypt(data,1); },
  
  /**
   * The expanded S-box and inverse S-box tables.  These will be computed
   * on the client so that we don't have to send them down the wire.
   *
   * There are two tables, _tables[0] is for encryption and
   * _tables[1] is for decryption.
   *
   * The first 4 sub-tables are the expanded S-box with MixColumns.  The
   * last (_tables[01][4]) is the S-box itself.
   *
   * @private
   */
  _tables: [[[],[],[],[],[]],[[],[],[],[],[]]],

  /**
   * Expand the S-box tables.
   *
   * @private
   */
  _precompute: function () {
   var encTable = this._tables[0], decTable = this._tables[1],
       sbox = encTable[4], sboxInv = decTable[4],
       i, x, xInv, d=[], th=[], x2, x4, x8, s, tEnc, tDec;

    // Compute double and third tables
   for (i = 0; i < 256; i++) {
     th[( d[i] = i<<1 ^ (i>>7)*283 )^i]=i;
   }
   
   for (x = xInv = 0; !sbox[x]; x ^= x2 || 1, xInv = th[xInv] || 1) {
     // Compute sbox
     s = xInv ^ xInv<<1 ^ xInv<<2 ^ xInv<<3 ^ xInv<<4;
     s = s>>8 ^ s&255 ^ 99;
     sbox[x] = s;
     sboxInv[s] = x;
     
     // Compute MixColumns
     x8 = d[x4 = d[x2 = d[x]]];
     tDec = x8*0x1010101 ^ x4*0x10001 ^ x2*0x101 ^ x*0x1010100;
     tEnc = d[s]*0x101 ^ s*0x1010100;
     
     for (i = 0; i < 4; i++) {
       encTable[i][x] = tEnc = tEnc<<24 ^ tEnc>>>8;
       decTable[i][s] = tDec = tDec<<24 ^ tDec>>>8;
     }
   }
   
   // Compactify.  Considerable speedup on Firefox.
   for (i = 0; i < 5; i++) {
     encTable[i] = encTable[i].slice(0);
     decTable[i] = decTable[i].slice(0);
   }
  },
  
  /**
   * Encryption and decryption core.
   * @param {Array} input Four words to be encrypted or decrypted.
   * @param dir The direction, 0 for encrypt and 1 for decrypt.
   * @return {Array} The four encrypted or decrypted words.
   * @private
   */
  _crypt:function (input, dir) {
    if (input.length !== 4) {
      throw new sjcl.exception.invalid("invalid aes block size");
    }
    
    var key = this._key[dir],
        // state variables a,b,c,d are loaded with pre-whitened data
        a = input[0]           ^ key[0],
        b = input[dir ? 3 : 1] ^ key[1],
        c = input[2]           ^ key[2],
        d = input[dir ? 1 : 3] ^ key[3],
        a2, b2, c2,
        
        nInnerRounds = key.length/4 - 2,
        i,
        kIndex = 4,
        out = [0,0,0,0],
        table = this._tables[dir],
        
        // load up the tables
        t0    = table[0],
        t1    = table[1],
        t2    = table[2],
        t3    = table[3],
        sbox  = table[4];
 
    // Inner rounds.  Cribbed from OpenSSL.
    for (i = 0; i < nInnerRounds; i++) {
      a2 = t0[a>>>24] ^ t1[b>>16 & 255] ^ t2[c>>8 & 255] ^ t3[d & 255] ^ key[kIndex];
      b2 = t0[b>>>24] ^ t1[c>>16 & 255] ^ t2[d>>8 & 255] ^ t3[a & 255] ^ key[kIndex + 1];
      c2 = t0[c>>>24] ^ t1[d>>16 & 255] ^ t2[a>>8 & 255] ^ t3[b & 255] ^ key[kIndex + 2];
      d  = t0[d>>>24] ^ t1[a>>16 & 255] ^ t2[b>>8 & 255] ^ t3[c & 255] ^ key[kIndex + 3];
      kIndex += 4;
      a=a2; b=b2; c=c2;
    }
        
    // Last round.
    for (i = 0; i < 4; i++) {
      out[dir ? 3&-i : i] =
        sbox[a>>>24      ]<<24 ^ 
        sbox[b>>16  & 255]<<16 ^
        sbox[c>>8   & 255]<<8  ^
        sbox[d      & 255]     ^
        key[kIndex++];
      a2=a; a=b; b=c; c=d; d=a2;
    }
    
    return out;
  }
};

/** @fileOverview Arrays of bits, encoded as arrays of Numbers.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

/** @namespace Arrays of bits, encoded as arrays of Numbers.
 *
 * @description
 * <p>
 * These objects are the currency accepted by SJCL's crypto functions.
 * </p>
 *
 * <p>
 * Most of our crypto primitives operate on arrays of 4-byte words internally,
 * but many of them can take arguments that are not a multiple of 4 bytes.
 * This library encodes arrays of bits (whose size need not be a multiple of 8
 * bits) as arrays of 32-bit words.  The bits are packed, big-endian, into an
 * array of words, 32 bits at a time.  Since the words are double-precision
 * floating point numbers, they fit some extra data.  We use this (in a private,
 * possibly-changing manner) to encode the number of bits actually  present
 * in the last word of the array.
 * </p>
 *
 * <p>
 * Because bitwise ops clear this out-of-band data, these arrays can be passed
 * to ciphers like AES which want arrays of words.
 * </p>
 */
sjcl.bitArray = {
  /**
   * Array slices in units of bits.
   * @param {bitArray} a The array to slice.
   * @param {Number} bstart The offset to the start of the slice, in bits.
   * @param {Number} bend The offset to the end of the slice, in bits.  If this is undefined,
   * slice until the end of the array.
   * @return {bitArray} The requested slice.
   */
  bitSlice: function (a, bstart, bend) {
    a = sjcl.bitArray._shiftRight(a.slice(bstart/32), 32 - (bstart & 31)).slice(1);
    return (bend === undefined) ? a : sjcl.bitArray.clamp(a, bend-bstart);
  },

  /**
   * Extract a number packed into a bit array.
   * @param {bitArray} a The array to slice.
   * @param {Number} bstart The offset to the start of the slice, in bits.
   * @param {Number} length The length of the number to extract.
   * @return {Number} The requested slice.
   */
  extract: function(a, bstart, blength) {
    // FIXME: this Math.floor is not necessary at all, but for some reason
    // seems to suppress a bug in the Chromium JIT.
    var x, sh = Math.floor((-bstart-blength) & 31);
    if ((bstart + blength - 1 ^ bstart) & -32) {
      // it crosses a boundary
      x = (a[bstart/32|0] << (32 - sh)) ^ (a[bstart/32+1|0] >>> sh);
    } else {
      // within a single word
      x = a[bstart/32|0] >>> sh;
    }
    return x & ((1<<blength) - 1);
  },

  /**
   * Concatenate two bit arrays.
   * @param {bitArray} a1 The first array.
   * @param {bitArray} a2 The second array.
   * @return {bitArray} The concatenation of a1 and a2.
   */
  concat: function (a1, a2) {
    if (a1.length === 0 || a2.length === 0) {
      return a1.concat(a2);
    }
    
    var out, i, last = a1[a1.length-1], shift = sjcl.bitArray.getPartial(last);
    if (shift === 32) {
      return a1.concat(a2);
    } else {
      return sjcl.bitArray._shiftRight(a2, shift, last|0, a1.slice(0,a1.length-1));
    }
  },

  /**
   * Find the length of an array of bits.
   * @param {bitArray} a The array.
   * @return {Number} The length of a, in bits.
   */
  bitLength: function (a) {
    var l = a.length, x;
    if (l === 0) { return 0; }
    x = a[l - 1];
    return (l-1) * 32 + sjcl.bitArray.getPartial(x);
  },

  /**
   * Truncate an array.
   * @param {bitArray} a The array.
   * @param {Number} len The length to truncate to, in bits.
   * @return {bitArray} A new array, truncated to len bits.
   */
  clamp: function (a, len) {
    if (a.length * 32 < len) { return a; }
    a = a.slice(0, Math.ceil(len / 32));
    var l = a.length;
    len = len & 31;
    if (l > 0 && len) {
      a[l-1] = sjcl.bitArray.partial(len, a[l-1] & 0x80000000 >> (len-1), 1);
    }
    return a;
  },

  /**
   * Make a partial word for a bit array.
   * @param {Number} len The number of bits in the word.
   * @param {Number} x The bits.
   * @param {Number} [0] _end Pass 1 if x has already been shifted to the high side.
   * @return {Number} The partial word.
   */
  partial: function (len, x, _end) {
    if (len === 32) { return x; }
    return (_end ? x|0 : x << (32-len)) + len * 0x10000000000;
  },

  /**
   * Get the number of bits used by a partial word.
   * @param {Number} x The partial word.
   * @return {Number} The number of bits used by the partial word.
   */
  getPartial: function (x) {
    return Math.round(x/0x10000000000) || 32;
  },

  /**
   * Compare two arrays for equality in a predictable amount of time.
   * @param {bitArray} a The first array.
   * @param {bitArray} b The second array.
   * @return {boolean} true if a == b; false otherwise.
   */
  equal: function (a, b) {
    if (sjcl.bitArray.bitLength(a) !== sjcl.bitArray.bitLength(b)) {
      return false;
    }
    var x = 0, i;
    for (i=0; i<a.length; i++) {
      x |= a[i]^b[i];
    }
    return (x === 0);
  },

  /** Shift an array right.
   * @param {bitArray} a The array to shift.
   * @param {Number} shift The number of bits to shift.
   * @param {Number} [carry=0] A byte to carry in
   * @param {bitArray} [out=[]] An array to prepend to the output.
   * @private
   */
  _shiftRight: function (a, shift, carry, out) {
    var i, last2=0, shift2;
    if (out === undefined) { out = []; }
    
    for (; shift >= 32; shift -= 32) {
      out.push(carry);
      carry = 0;
    }
    if (shift === 0) {
      return out.concat(a);
    }
    
    for (i=0; i<a.length; i++) {
      out.push(carry | a[i]>>>shift);
      carry = a[i] << (32-shift);
    }
    last2 = a.length ? a[a.length-1] : 0;
    shift2 = sjcl.bitArray.getPartial(last2);
    out.push(sjcl.bitArray.partial(shift+shift2 & 31, (shift + shift2 > 32) ? carry : out.pop(),1));
    return out;
  },
  
  /** xor a block of 4 words together.
   * @private
   */
  _xor4: function(x,y) {
    return [x[0]^y[0],x[1]^y[1],x[2]^y[2],x[3]^y[3]];
  }
};
/** @fileOverview Bit array codec implementations.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */
 
/** @namespace UTF-8 strings */
sjcl.codec.utf8String = {
  /** Convert from a bitArray to a UTF-8 string. */
  fromBits: function (arr) {
    var out = "", bl = sjcl.bitArray.bitLength(arr), i, tmp;
    for (i=0; i<bl/8; i++) {
      if ((i&3) === 0) {
        tmp = arr[i/4];
      }
      out += String.fromCharCode(tmp >>> 24);
      tmp <<= 8;
    }
    return decodeURIComponent(escape(out));
  },
  
  /** Convert from a UTF-8 string to a bitArray. */
  toBits: function (str) {
    str = unescape(encodeURIComponent(str));
    var out = [], i, tmp=0;
    for (i=0; i<str.length; i++) {
      tmp = tmp << 8 | str.charCodeAt(i);
      if ((i&3) === 3) {
        out.push(tmp);
        tmp = 0;
      }
    }
    if (i&3) {
      out.push(sjcl.bitArray.partial(8*(i&3), tmp));
    }
    return out;
  }
};
/** @fileOverview Bit array codec implementations.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

/** @namespace Base64 encoding/decoding */
sjcl.codec.base64 = {
  /** The base64 alphabet.
   * @private
   */
  _chars: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
  
  /** Convert from a bitArray to a base64 string. */
  fromBits: function (arr, _noEquals, _url) {
    var out = "", i, bits=0, c = sjcl.codec.base64._chars, ta=0, bl = sjcl.bitArray.bitLength(arr);
    if (_url) {
      c = c.substr(0,62) + '-_';
    }
    for (i=0; out.length * 6 < bl; ) {
      out += c.charAt((ta ^ arr[i]>>>bits) >>> 26);
      if (bits < 6) {
        ta = arr[i] << (6-bits);
        bits += 26;
        i++;
      } else {
        ta <<= 6;
        bits -= 6;
      }
    }
    while ((out.length & 3) && !_noEquals) { out += "="; }
    return out;
  },
  
  /** Convert from a base64 string to a bitArray */
  toBits: function(str, _url) {
    str = str.replace(/\s|=/g,'');
    var out = [], i, bits=0, c = sjcl.codec.base64._chars, ta=0, x;
    if (_url) {
      c = c.substr(0,62) + '-_';
    }
    for (i=0; i<str.length; i++) {
      x = c.indexOf(str.charAt(i));
      if (x < 0) {
        throw new sjcl.exception.invalid("this isn't base64!");
      }
      if (bits > 26) {
        bits -= 26;
        out.push(ta ^ x>>>bits);
        ta  = x << (32-bits);
      } else {
        bits += 6;
        ta ^= x << (32-bits);
      }
    }
    if (bits&56) {
      out.push(sjcl.bitArray.partial(bits&56, ta, 1));
    }
    return out;
  }
};

sjcl.codec.base64url = {
  fromBits: function (arr) { return sjcl.codec.base64.fromBits(arr,1,1); },
  toBits: function (str) { return sjcl.codec.base64.toBits(str,1); }
};
/** @fileOverview Javascript SHA-256 implementation.
 *
 * An older version of this implementation is available in the public
 * domain, but this one is (c) Emily Stark, Mike Hamburg, Dan Boneh,
 * Stanford University 2008-2010 and BSD-licensed for liability
 * reasons.
 *
 * Special thanks to Aldo Cortesi for pointing out several bugs in
 * this code.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

/**
 * Context for a SHA-256 operation in progress.
 * @constructor
 * @class Secure Hash Algorithm, 256 bits.
 */
sjcl.hash.sha256 = function (hash) {
  if (!this._key[0]) { this._precompute(); }
  if (hash) {
    this._h = hash._h.slice(0);
    this._buffer = hash._buffer.slice(0);
    this._length = hash._length;
  } else {
    this.reset();
  }
};

/**
 * Hash a string or an array of words.
 * @static
 * @param {bitArray|String} data the data to hash.
 * @return {bitArray} The hash value, an array of 16 big-endian words.
 */
sjcl.hash.sha256.hash = function (data) {
  return (new sjcl.hash.sha256()).update(data).finalize();
};

sjcl.hash.sha256.prototype = {
  /**
   * The hash's block size, in bits.
   * @constant
   */
  blockSize: 512,
   
  /**
   * Reset the hash state.
   * @return this
   */
  reset:function () {
    this._h = this._init.slice(0);
    this._buffer = [];
    this._length = 0;
    return this;
  },
  
  /**
   * Input several words to the hash.
   * @param {bitArray|String} data the data to hash.
   * @return this
   */
  update: function (data) {
    if (typeof data === "string") {
      data = sjcl.codec.utf8String.toBits(data);
    }
    var i, b = this._buffer = sjcl.bitArray.concat(this._buffer, data),
        ol = this._length,
        nl = this._length = ol + sjcl.bitArray.bitLength(data);
    for (i = 512+ol & -512; i <= nl; i+= 512) {
      this._block(b.splice(0,16));
    }
    return this;
  },
  
  /**
   * Complete hashing and output the hash value.
   * @return {bitArray} The hash value, an array of 8 big-endian words.
   */
  finalize:function () {
    var i, b = this._buffer, h = this._h;

    // Round out and push the buffer
    b = sjcl.bitArray.concat(b, [sjcl.bitArray.partial(1,1)]);
    
    // Round out the buffer to a multiple of 16 words, less the 2 length words.
    for (i = b.length + 2; i & 15; i++) {
      b.push(0);
    }
    
    // append the length
    b.push(Math.floor(this._length / 0x100000000));
    b.push(this._length | 0);

    while (b.length) {
      this._block(b.splice(0,16));
    }

    this.reset();
    return h;
  },

  /**
   * The SHA-256 initialization vector, to be precomputed.
   * @private
   */
  _init:[],
  /*
  _init:[0x6a09e667,0xbb67ae85,0x3c6ef372,0xa54ff53a,0x510e527f,0x9b05688c,0x1f83d9ab,0x5be0cd19],
  */
  
  /**
   * The SHA-256 hash key, to be precomputed.
   * @private
   */
  _key:[],
  /*
  _key:
    [0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
     0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
     0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
     0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
     0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
     0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
     0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
     0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2],
  */


  /**
   * Function to precompute _init and _key.
   * @private
   */
  _precompute: function () {
    var i = 0, prime = 2, factor;

    function frac(x) { return (x-Math.floor(x)) * 0x100000000 | 0; }

    outer: for (; i<64; prime++) {
      for (factor=2; factor*factor <= prime; factor++) {
        if (prime % factor === 0) {
          // not a prime
          continue outer;
        }
      }
      
      if (i<8) {
        this._init[i] = frac(Math.pow(prime, 1/2));
      }
      this._key[i] = frac(Math.pow(prime, 1/3));
      i++;
    }
  },
  
  /**
   * Perform one cycle of SHA-256.
   * @param {bitArray} words one block of words.
   * @private
   */
  _block:function (words) {  
    var i, tmp, a, b,
      w = words.slice(0),
      h = this._h,
      k = this._key,
      h0 = h[0], h1 = h[1], h2 = h[2], h3 = h[3],
      h4 = h[4], h5 = h[5], h6 = h[6], h7 = h[7];

    /* Rationale for placement of |0 :
     * If a value can overflow is original 32 bits by a factor of more than a few
     * million (2^23 ish), there is a possibility that it might overflow the
     * 53-bit mantissa and lose precision.
     *
     * To avoid this, we clamp back to 32 bits by |'ing with 0 on any value that
     * propagates around the loop, and on the hash state h[].  I don't believe
     * that the clamps on h4 and on h0 are strictly necessary, but it's close
     * (for h4 anyway), and better safe than sorry.
     *
     * The clamps on h[] are necessary for the output to be correct even in the
     * common case and for short inputs.
     */
    for (i=0; i<64; i++) {
      // load up the input word for this round
      if (i<16) {
        tmp = w[i];
      } else {
        a   = w[(i+1 ) & 15];
        b   = w[(i+14) & 15];
        tmp = w[i&15] = ((a>>>7  ^ a>>>18 ^ a>>>3  ^ a<<25 ^ a<<14) + 
                         (b>>>17 ^ b>>>19 ^ b>>>10 ^ b<<15 ^ b<<13) +
                         w[i&15] + w[(i+9) & 15]) | 0;
      }
      
      tmp = (tmp + h7 + (h4>>>6 ^ h4>>>11 ^ h4>>>25 ^ h4<<26 ^ h4<<21 ^ h4<<7) +  (h6 ^ h4&(h5^h6)) + k[i]); // | 0;
      
      // shift register
      h7 = h6; h6 = h5; h5 = h4;
      h4 = h3 + tmp | 0;
      h3 = h2; h2 = h1; h1 = h0;

      h0 = (tmp +  ((h1&h2) ^ (h3&(h1^h2))) + (h1>>>2 ^ h1>>>13 ^ h1>>>22 ^ h1<<30 ^ h1<<19 ^ h1<<10)) | 0;
    }

    h[0] = h[0]+h0 | 0;
    h[1] = h[1]+h1 | 0;
    h[2] = h[2]+h2 | 0;
    h[3] = h[3]+h3 | 0;
    h[4] = h[4]+h4 | 0;
    h[5] = h[5]+h5 | 0;
    h[6] = h[6]+h6 | 0;
    h[7] = h[7]+h7 | 0;
  }
};


/** @fileOverview Javascript SHA-512 implementation.
 *
 * This implementation was written for CryptoJS by Jeff Mott and adapted for
 * SJCL by Stefan Thomas.
 *
 * CryptoJS (c) 2009–2012 by Jeff Mott. All rights reserved.
 * Released with New BSD License
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 * @author Jeff Mott
 * @author Stefan Thomas
 */

/**
 * Context for a SHA-512 operation in progress.
 * @constructor
 * @class Secure Hash Algorithm, 512 bits.
 */
sjcl.hash.sha512 = function (hash) {
  if (!this._key[0]) { this._precompute(); }
  if (hash) {
    this._h = hash._h.slice(0);
    this._buffer = hash._buffer.slice(0);
    this._length = hash._length;
  } else {
    this.reset();
  }
};

/**
 * Hash a string or an array of words.
 * @static
 * @param {bitArray|String} data the data to hash.
 * @return {bitArray} The hash value, an array of 16 big-endian words.
 */
sjcl.hash.sha512.hash = function (data) {
  return (new sjcl.hash.sha512()).update(data).finalize();
};

sjcl.hash.sha512.prototype = {
  /**
   * The hash's block size, in bits.
   * @constant
   */
  blockSize: 1024,
   
  /**
   * Reset the hash state.
   * @return this
   */
  reset:function () {
    this._h = this._init.slice(0);
    this._buffer = [];
    this._length = 0;
    return this;
  },
  
  /**
   * Input several words to the hash.
   * @param {bitArray|String} data the data to hash.
   * @return this
   */
  update: function (data) {
    if (typeof data === "string") {
      data = sjcl.codec.utf8String.toBits(data);
    }
    var i, b = this._buffer = sjcl.bitArray.concat(this._buffer, data),
        ol = this._length,
        nl = this._length = ol + sjcl.bitArray.bitLength(data);
    for (i = 1024+ol & -1024; i <= nl; i+= 1024) {
      this._block(b.splice(0,32));
    }
    return this;
  },
  
  /**
   * Complete hashing and output the hash value.
   * @return {bitArray} The hash value, an array of 16 big-endian words.
   */
  finalize:function () {
    var i, b = this._buffer, h = this._h;

    // Round out and push the buffer
    b = sjcl.bitArray.concat(b, [sjcl.bitArray.partial(1,1)]);

    // Round out the buffer to a multiple of 32 words, less the 4 length words.
    for (i = b.length + 4; i & 31; i++) {
      b.push(0);
    }

    // append the length
    b.push(0);
    b.push(0);
    b.push(Math.floor(this._length / 0x100000000));
    b.push(this._length | 0);

    while (b.length) {
      this._block(b.splice(0,32));
    }

    this.reset();
    return h;
  },

  /**
   * The SHA-512 initialization vector, to be precomputed.
   * @private
   */
  _init:[],

  /**
   * Least significant 24 bits of SHA512 initialization values.
   *
   * Javascript only has 53 bits of precision, so we compute the 40 most
   * significant bits and add the remaining 24 bits as constants.
   *
   * @private
   */
  _initr: [ 0xbcc908, 0xcaa73b, 0x94f82b, 0x1d36f1, 0xe682d1, 0x3e6c1f, 0x41bd6b, 0x7e2179 ],

  /*
  _init:
  [0x6a09e667, 0xf3bcc908, 0xbb67ae85, 0x84caa73b, 0x3c6ef372, 0xfe94f82b, 0xa54ff53a, 0x5f1d36f1,
   0x510e527f, 0xade682d1, 0x9b05688c, 0x2b3e6c1f, 0x1f83d9ab, 0xfb41bd6b, 0x5be0cd19, 0x137e2179],
  */

  /**
   * The SHA-512 hash key, to be precomputed.
   * @private
   */
  _key:[],

  /**
   * Least significant 24 bits of SHA512 key values.
   * @private
   */
  _keyr:
  [0x28ae22, 0xef65cd, 0x4d3b2f, 0x89dbbc, 0x48b538, 0x05d019, 0x194f9b, 0x6d8118,
   0x030242, 0x706fbe, 0xe4b28c, 0xffb4e2, 0x7b896f, 0x1696b1, 0xc71235, 0x692694,
   0xf14ad2, 0x4f25e3, 0x8cd5b5, 0xac9c65, 0x2b0275, 0xa6e483, 0x41fbd4, 0x1153b5,
   0x66dfab, 0xb43210, 0xfb213f, 0xef0ee4, 0xa88fc2, 0x0aa725, 0x03826f, 0x0e6e70,
   0xd22ffc, 0x26c926, 0xc42aed, 0x95b3df, 0xaf63de, 0x77b2a8, 0xedaee6, 0x82353b,
   0xf10364, 0x423001, 0xf89791, 0x54be30, 0xef5218, 0x65a910, 0x71202a, 0xbbd1b8,
   0xd2d0c8, 0x41ab53, 0x8eeb99, 0x9b48a8, 0xc95a63, 0x418acb, 0x63e373, 0xb2b8a3,
   0xefb2fc, 0x172f60, 0xf0ab72, 0x6439ec, 0x631e28, 0x82bde9, 0xc67915, 0x72532b,
   0x26619c, 0xc0c207, 0xe0eb1e, 0x6ed178, 0x176fba, 0xc898a6, 0xf90dae, 0x1c471b,
   0x047d84, 0xc72493, 0xc9bebc, 0x100d4c, 0x3e42b6, 0x657e2a, 0xd6faec, 0x475817],

  /*
  _key:
  [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 to precompute _init and _key.
   * @private
   */
  _precompute: function () {
    // XXX: This code is for precomputing the SHA256 constants, change for
    //      SHA512 and re-enable.
    var i = 0, prime = 2, factor;

    function frac(x)  { return (x-Math.floor(x)) * 0x100000000 | 0; }
    function frac2(x) { return (x-Math.floor(x)) * 0x10000000000 & 0xff; }

    outer: for (; i<80; prime++) {
      for (factor=2; factor*factor <= prime; factor++) {
        if (prime % factor === 0) {
          // not a prime
          continue outer;
        }
      }

      if (i<8) {
        this._init[i*2] = frac(Math.pow(prime, 1/2));
        this._init[i*2+1] = (frac2(Math.pow(prime, 1/2)) << 24) | this._initr[i];
      }
      this._key[i*2] = frac(Math.pow(prime, 1/3));
      this._key[i*2+1] = (frac2(Math.pow(prime, 1/3)) << 24) | this._keyr[i];
      i++;
    }
  },

  /**
   * Perform one cycle of SHA-512.
   * @param {bitArray} words one block of words.
   * @private
   */
  _block:function (words) {
    var i, wrh, wrl,
        w = words.slice(0),
        h = this._h,
        k = this._key,
        h0h = h[ 0], h0l = h[ 1], h1h = h[ 2], h1l = h[ 3],
        h2h = h[ 4], h2l = h[ 5], h3h = h[ 6], h3l = h[ 7],
        h4h = h[ 8], h4l = h[ 9], h5h = h[10], h5l = h[11],
        h6h = h[12], h6l = h[13], h7h = h[14], h7l = h[15];

    // Working variables
    var ah = h0h, al = h0l, bh = h1h, bl = h1l,
        ch = h2h, cl = h2l, dh = h3h, dl = h3l,
        eh = h4h, el = h4l, fh = h5h, fl = h5l,
        gh = h6h, gl = h6l, hh = h7h, hl = h7l;

    for (i=0; i<80; i++) {
      // load up the input word for this round
      if (i<16) {
        wrh = w[i * 2];
        wrl = w[i * 2 + 1];
      } else {
        // Gamma0
        var gamma0xh = w[(i-15) * 2];
        var gamma0xl = w[(i-15) * 2 + 1];
        var gamma0h =
          ((gamma0xl << 31) | (gamma0xh >>> 1)) ^
          ((gamma0xl << 24) | (gamma0xh >>> 8)) ^
           (gamma0xh >>> 7);
        var gamma0l =
          ((gamma0xh << 31) | (gamma0xl >>> 1)) ^
          ((gamma0xh << 24) | (gamma0xl >>> 8)) ^
          ((gamma0xh << 25) | (gamma0xl >>> 7));

        // Gamma1
        var gamma1xh = w[(i-2) * 2];
        var gamma1xl = w[(i-2) * 2 + 1];
        var gamma1h =
          ((gamma1xl << 13) | (gamma1xh >>> 19)) ^
          ((gamma1xh << 3)  | (gamma1xl >>> 29)) ^
           (gamma1xh >>> 6);
        var gamma1l =
          ((gamma1xh << 13) | (gamma1xl >>> 19)) ^
          ((gamma1xl << 3)  | (gamma1xh >>> 29)) ^
          ((gamma1xh << 26) | (gamma1xl >>> 6));

        // Shortcuts
        var wr7h = w[(i-7) * 2];
        var wr7l = w[(i-7) * 2 + 1];

        var wr16h = w[(i-16) * 2];
        var wr16l = w[(i-16) * 2 + 1];

        // W(round) = gamma0 + W(round - 7) + gamma1 + W(round - 16)
        wrl = gamma0l + wr7l;
        wrh = gamma0h + wr7h + ((wrl >>> 0) < (gamma0l >>> 0) ? 1 : 0);
        wrl += gamma1l;
        wrh += gamma1h + ((wrl >>> 0) < (gamma1l >>> 0) ? 1 : 0);
        wrl += wr16l;
        wrh += wr16h + ((wrl >>> 0) < (wr16l >>> 0) ? 1 : 0);
      }

      w[i*2]     = wrh |= 0;
      w[i*2 + 1] = wrl |= 0;

      // Ch
      var chh = (eh & fh) ^ (~eh & gh);
      var chl = (el & fl) ^ (~el & gl);

      // Maj
      var majh = (ah & bh) ^ (ah & ch) ^ (bh & ch);
      var majl = (al & bl) ^ (al & cl) ^ (bl & cl);

      // Sigma0
      var sigma0h = ((al << 4) | (ah >>> 28)) ^ ((ah << 30) | (al >>> 2)) ^ ((ah << 25) | (al >>> 7));
      var sigma0l = ((ah << 4) | (al >>> 28)) ^ ((al << 30) | (ah >>> 2)) ^ ((al << 25) | (ah >>> 7));

      // Sigma1
      var sigma1h = ((el << 18) | (eh >>> 14)) ^ ((el << 14) | (eh >>> 18)) ^ ((eh << 23) | (el >>> 9));
      var sigma1l = ((eh << 18) | (el >>> 14)) ^ ((eh << 14) | (el >>> 18)) ^ ((el << 23) | (eh >>> 9));

      // K(round)
      var krh = k[i*2];
      var krl = k[i*2+1];

      // t1 = h + sigma1 + ch + K(round) + W(round)
      var t1l = hl + sigma1l;
      var t1h = hh + sigma1h + ((t1l >>> 0) < (hl >>> 0) ? 1 : 0);
      t1l += chl;
      t1h += chh + ((t1l >>> 0) < (chl >>> 0) ? 1 : 0);
      t1l += krl;
      t1h += krh + ((t1l >>> 0) < (krl >>> 0) ? 1 : 0);
      t1l += wrl;
      t1h += wrh + ((t1l >>> 0) < (wrl >>> 0) ? 1 : 0);

      // t2 = sigma0 + maj
      var t2l = sigma0l + majl;
      var t2h = sigma0h + majh + ((t2l >>> 0) < (sigma0l >>> 0) ? 1 : 0);

      // Update working variables
      hh = gh;
      hl = gl;
      gh = fh;
      gl = fl;
      fh = eh;
      fl = el;
      el = (dl + t1l) | 0;
      eh = (dh + t1h + ((el >>> 0) < (dl >>> 0) ? 1 : 0)) | 0;
      dh = ch;
      dl = cl;
      ch = bh;
      cl = bl;
      bh = ah;
      bl = al;
      al = (t1l + t2l) | 0;
      ah = (t1h + t2h + ((al >>> 0) < (t1l >>> 0) ? 1 : 0)) | 0;
    }

    // Intermediate hash
    h0l = h[1] = (h0l + al) | 0;
    h[0] = (h0h + ah + ((h0l >>> 0) < (al >>> 0) ? 1 : 0)) | 0;
    h1l = h[3] = (h1l + bl) | 0;
    h[2] = (h1h + bh + ((h1l >>> 0) < (bl >>> 0) ? 1 : 0)) | 0;
    h2l = h[5] = (h2l + cl) | 0;
    h[4] = (h2h + ch + ((h2l >>> 0) < (cl >>> 0) ? 1 : 0)) | 0;
    h3l = h[7] = (h3l + dl) | 0;
    h[6] = (h3h + dh + ((h3l >>> 0) < (dl >>> 0) ? 1 : 0)) | 0;
    h4l = h[9] = (h4l + el) | 0;
    h[8] = (h4h + eh + ((h4l >>> 0) < (el >>> 0) ? 1 : 0)) | 0;
    h5l = h[11] = (h5l + fl) | 0;
    h[10] = (h5h + fh + ((h5l >>> 0) < (fl >>> 0) ? 1 : 0)) | 0;
    h6l = h[13] = (h6l + gl) | 0;
    h[12] = (h6h + gh + ((h6l >>> 0) < (gl >>> 0) ? 1 : 0)) | 0;
    h7l = h[15] = (h7l + hl) | 0;
    h[14] = (h7h + hh + ((h7l >>> 0) < (hl >>> 0) ? 1 : 0)) | 0;
  }
};


/** @fileOverview Javascript SHA-1 implementation.
 *
 * Based on the implementation in RFC 3174, method 1, and on the SJCL
 * SHA-256 implementation.
 *
 * @author Quinn Slack
 */

/**
 * Context for a SHA-1 operation in progress.
 * @constructor
 * @class Secure Hash Algorithm, 160 bits.
 */
sjcl.hash.sha1 = function (hash) {
  if (hash) {
    this._h = hash._h.slice(0);
    this._buffer = hash._buffer.slice(0);
    this._length = hash._length;
  } else {
    this.reset();
  }
};

/**
 * Hash a string or an array of words.
 * @static
 * @param {bitArray|String} data the data to hash.
 * @return {bitArray} The hash value, an array of 5 big-endian words.
 */
sjcl.hash.sha1.hash = function (data) {
  return (new sjcl.hash.sha1()).update(data).finalize();
};

sjcl.hash.sha1.prototype = {
  /**
   * The hash's block size, in bits.
   * @constant
   */
  blockSize: 512,
   
  /**
   * Reset the hash state.
   * @return this
   */
  reset:function () {
    this._h = this._init.slice(0);
    this._buffer = [];
    this._length = 0;
    return this;
  },
  
  /**
   * Input several words to the hash.
   * @param {bitArray|String} data the data to hash.
   * @return this
   */
  update: function (data) {
    if (typeof data === "string") {
      data = sjcl.codec.utf8String.toBits(data);
    }
    var i, b = this._buffer = sjcl.bitArray.concat(this._buffer, data),
        ol = this._length,
        nl = this._length = ol + sjcl.bitArray.bitLength(data);
    for (i = this.blockSize+ol & -this.blockSize; i <= nl;
         i+= this.blockSize) {
      this._block(b.splice(0,16));
    }
    return this;
  },
  
  /**
   * Complete hashing and output the hash value.
   * @return {bitArray} The hash value, an array of 5 big-endian words. TODO
   */
  finalize:function () {
    var i, b = this._buffer, h = this._h;

    // Round out and push the buffer
    b = sjcl.bitArray.concat(b, [sjcl.bitArray.partial(1,1)]);
    // Round out the buffer to a multiple of 16 words, less the 2 length words.
    for (i = b.length + 2; i & 15; i++) {
      b.push(0);
    }

    // append the length
    b.push(Math.floor(this._length / 0x100000000));
    b.push(this._length | 0);

    while (b.length) {
      this._block(b.splice(0,16));
    }

    this.reset();
    return h;
  },

  /**
   * The SHA-1 initialization vector.
   * @private
   */
  _init:[0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0],

  /**
   * The SHA-1 hash key.
   * @private
   */
  _key:[0x5A827999, 0x6ED9EBA1, 0x8F1BBCDC, 0xCA62C1D6],

  /**
   * The SHA-1 logical functions f(0), f(1), ..., f(79).
   * @private
   */
  _f:function(t, b, c, d) {
    if (t <= 19) {
      return (b & c) | (~b & d);
    } else if (t <= 39) {
      return b ^ c ^ d;
    } else if (t <= 59) {
      return (b & c) | (b & d) | (c & d);
    } else if (t <= 79) {
      return b ^ c ^ d;
    }
  },

  /**
   * Circular left-shift operator.
   * @private
   */
  _S:function(n, x) {
    return (x << n) | (x >>> 32-n);
  },
  
  /**
   * Perform one cycle of SHA-1.
   * @param {bitArray} words one block of words.
   * @private
   */
  _block:function (words) {  
    var t, tmp, a, b, c, d, e,
    w = words.slice(0),
    h = this._h,
    k = this._key;
   
    a = h[0]; b = h[1]; c = h[2]; d = h[3]; e = h[4]; 

    for (t=0; t<=79; t++) {
      if (t >= 16) {
        w[t] = this._S(1, w[t-3] ^ w[t-8] ^ w[t-14] ^ w[t-16]);
      }
      tmp = (this._S(5, a) + this._f(t, b, c, d) + e + w[t] +
             this._key[Math.floor(t/20)]) | 0;
      e = d;
      d = c;
      c = this._S(30, b);
      b = a;
      a = tmp;
   }

   h[0] = (h[0]+a) |0;
   h[1] = (h[1]+b) |0;
   h[2] = (h[2]+c) |0;
   h[3] = (h[3]+d) |0;
   h[4] = (h[4]+e) |0;
  }
};
/** @fileOverview CCM mode implementation.
 *
 * Special thanks to Roy Nicholson for pointing out a bug in our
 * implementation.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

/** @namespace CTR mode with CBC MAC. */
sjcl.mode.ccm = {
  /** The name of the mode.
   * @constant
   */
  name: "ccm",
  
  /** Encrypt in CCM mode.
   * @static
   * @param {Object} prf The pseudorandom function.  It must have a block size of 16 bytes.
   * @param {bitArray} plaintext The plaintext data.
   * @param {bitArray} iv The initialization value.
   * @param {bitArray} [adata=[]] The authenticated data.
   * @param {Number} [tlen=64] the desired tag length, in bits.
   * @return {bitArray} The encrypted data, an array of bytes.
   */
  encrypt: function(prf, plaintext, iv, adata, tlen) {
    var L, i, out = plaintext.slice(0), tag, w=sjcl.bitArray, ivl = w.bitLength(iv) / 8, ol = w.bitLength(out) / 8;
    tlen = tlen || 64;
    adata = adata || [];
    
    if (ivl < 7) {
      throw new sjcl.exception.invalid("ccm: iv must be at least 7 bytes");
    }
    
    // compute the length of the length
    for (L=2; L<4 && ol >>> 8*L; L++) {}
    if (L < 15 - ivl) { L = 15-ivl; }
    iv = w.clamp(iv,8*(15-L));
    
    // compute the tag
    tag = sjcl.mode.ccm._computeTag(prf, plaintext, iv, adata, tlen, L);
    
    // encrypt
    out = sjcl.mode.ccm._ctrMode(prf, out, iv, tag, tlen, L);
    
    return w.concat(out.data, out.tag);
  },
  
  /** Decrypt in CCM mode.
   * @static
   * @param {Object} prf The pseudorandom function.  It must have a block size of 16 bytes.
   * @param {bitArray} ciphertext The ciphertext data.
   * @param {bitArray} iv The initialization value.
   * @param {bitArray} [[]] adata The authenticated data.
   * @param {Number} [64] tlen the desired tag length, in bits.
   * @return {bitArray} The decrypted data.
   */
  decrypt: function(prf, ciphertext, iv, adata, tlen) {
    tlen = tlen || 64;
    adata = adata || [];
    var L, i, 
        w=sjcl.bitArray,
        ivl = w.bitLength(iv) / 8,
        ol = w.bitLength(ciphertext), 
        out = w.clamp(ciphertext, ol - tlen),
        tag = w.bitSlice(ciphertext, ol - tlen), tag2;
    

    ol = (ol - tlen) / 8;
        
    if (ivl < 7) {
      throw new sjcl.exception.invalid("ccm: iv must be at least 7 bytes");
    }
    
    // compute the length of the length
    for (L=2; L<4 && ol >>> 8*L; L++) {}
    if (L < 15 - ivl) { L = 15-ivl; }
    iv = w.clamp(iv,8*(15-L));
    
    // decrypt
    out = sjcl.mode.ccm._ctrMode(prf, out, iv, tag, tlen, L);
    
    // check the tag
    tag2 = sjcl.mode.ccm._computeTag(prf, out.data, iv, adata, tlen, L);
    if (!w.equal(out.tag, tag2)) {
      throw new sjcl.exception.corrupt("ccm: tag doesn't match");
    }
    
    return out.data;
  },

  /* Compute the (unencrypted) authentication tag, according to the CCM specification
   * @param {Object} prf The pseudorandom function.
   * @param {bitArray} plaintext The plaintext data.
   * @param {bitArray} iv The initialization value.
   * @param {bitArray} adata The authenticated data.
   * @param {Number} tlen the desired tag length, in bits.
   * @return {bitArray} The tag, but not yet encrypted.
   * @private
   */
  _computeTag: function(prf, plaintext, iv, adata, tlen, L) {
    // compute B[0]
    var q, mac, field = 0, offset = 24, tmp, i, macData = [], w=sjcl.bitArray, xor = w._xor4;

    tlen /= 8;
  
    // check tag length and message length
    if (tlen % 2 || tlen < 4 || tlen > 16) {
      throw new sjcl.exception.invalid("ccm: invalid tag length");
    }
  
    if (adata.length > 0xFFFFFFFF || plaintext.length > 0xFFFFFFFF) {
      // I don't want to deal with extracting high words from doubles.
      throw new sjcl.exception.bug("ccm: can't deal with 4GiB or more data");
    }

    // mac the flags
    mac = [w.partial(8, (adata.length ? 1<<6 : 0) | (tlen-2) << 2 | L-1)];

    // mac the iv and length
    mac = w.concat(mac, iv);
    mac[3] |= w.bitLength(plaintext)/8;
    mac = prf.encrypt(mac);
    
  
    if (adata.length) {
      // mac the associated data.  start with its length...
      tmp = w.bitLength(adata)/8;
      if (tmp <= 0xFEFF) {
        macData = [w.partial(16, tmp)];
      } else if (tmp <= 0xFFFFFFFF) {
        macData = w.concat([w.partial(16,0xFFFE)], [tmp]);
      } // else ...
    
      // mac the data itself
      macData = w.concat(macData, adata);
      for (i=0; i<macData.length; i += 4) {
        mac = prf.encrypt(xor(mac, macData.slice(i,i+4).concat([0,0,0])));
      }
    }
  
    // mac the plaintext
    for (i=0; i<plaintext.length; i+=4) {
      mac = prf.encrypt(xor(mac, plaintext.slice(i,i+4).concat([0,0,0])));
    }

    return w.clamp(mac, tlen * 8);
  },

  /** CCM CTR mode.
   * Encrypt or decrypt data and tag with the prf in CCM-style CTR mode.
   * May mutate its arguments.
   * @param {Object} prf The PRF.
   * @param {bitArray} data The data to be encrypted or decrypted.
   * @param {bitArray} iv The initialization vector.
   * @param {bitArray} tag The authentication tag.
   * @param {Number} tlen The length of th etag, in bits.
   * @param {Number} L The CCM L value.
   * @return {Object} An object with data and tag, the en/decryption of data and tag values.
   * @private
   */
  _ctrMode: function(prf, data, iv, tag, tlen, L) {
    var enc, i, w=sjcl.bitArray, xor = w._xor4, ctr, b, l = data.length, bl=w.bitLength(data);

    // start the ctr
    ctr = w.concat([w.partial(8,L-1)],iv).concat([0,0,0]).slice(0,4);
    
    // en/decrypt the tag
    tag = w.bitSlice(xor(tag,prf.encrypt(ctr)), 0, tlen);
  
    // en/decrypt the data
    if (!l) { return {tag:tag, data:[]}; }
    
    for (i=0; i<l; i+=4) {
      ctr[3]++;
      enc = prf.encrypt(ctr);
      data[i]   ^= enc[0];
      data[i+1] ^= enc[1];
      data[i+2] ^= enc[2];
      data[i+3] ^= enc[3];
    }
    return { tag:tag, data:w.clamp(data,bl) };
  }
};
/** @fileOverview HMAC implementation.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

/** HMAC with the specified hash function.
 * @constructor
 * @param {bitArray} key the key for HMAC.
 * @param {Object} [hash=sjcl.hash.sha256] The hash function to use.
 */
sjcl.misc.hmac = function (key, Hash) {
  this._hash = Hash = Hash || sjcl.hash.sha256;
  var exKey = [[],[]], i,
      bs = Hash.prototype.blockSize / 32;
  this._baseHash = [new Hash(), new Hash()];

  if (key.length > bs) {
    key = Hash.hash(key);
  }
  
  for (i=0; i<bs; i++) {
    exKey[0][i] = key[i]^0x36363636;
    exKey[1][i] = key[i]^0x5C5C5C5C;
  }
  
  this._baseHash[0].update(exKey[0]);
  this._baseHash[1].update(exKey[1]);
  this._resultHash = new Hash(this._baseHash[0]);
};

/** HMAC with the specified hash function.  Also called encrypt since it's a prf.
 * @param {bitArray|String} data The data to mac.
 */
sjcl.misc.hmac.prototype.encrypt = sjcl.misc.hmac.prototype.mac = function (data) {
  if (!this._updated) {
    this.update(data);
    return this.digest(data);
  } else {
    throw new sjcl.exception.invalid("encrypt on already updated hmac called!");
  }
};

sjcl.misc.hmac.prototype.reset = function () {
  this._resultHash = new this._hash(this._baseHash[0]);
  this._updated = false;
};

sjcl.misc.hmac.prototype.update = function (data) {
  this._updated = true;
  this._resultHash.update(data);
};

sjcl.misc.hmac.prototype.digest = function () {
  var w = this._resultHash.finalize(), result = new (this._hash)(this._baseHash[1]).update(w).finalize();

  this.reset();

  return result;
};/** @fileOverview Password-based key-derivation function, version 2.0.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

/** Password-Based Key-Derivation Function, version 2.0.
 *
 * Generate keys from passwords using PBKDF2-HMAC-SHA256.
 *
 * This is the method specified by RSA's PKCS #5 standard.
 *
 * @param {bitArray|String} password  The password.
 * @param {bitArray|String} salt The salt.  Should have lots of entropy.
 * @param {Number} [count=1000] The number of iterations.  Higher numbers make the function slower but more secure.
 * @param {Number} [length] The length of the derived key.  Defaults to the
                            output size of the hash function.
 * @param {Object} [Prff=sjcl.misc.hmac] The pseudorandom function family.
 * @return {bitArray} the derived key.
 */
sjcl.misc.pbkdf2 = function (password, salt, count, length, Prff) {
  count = count || 1000;
  
  if (length < 0 || count < 0) {
    throw sjcl.exception.invalid("invalid params to pbkdf2");
  }
  
  if (typeof password === "string") {
    password = sjcl.codec.utf8String.toBits(password);
  }
  
  if (typeof salt === "string") {
    salt = sjcl.codec.utf8String.toBits(salt);
  }
  
  Prff = Prff || sjcl.misc.hmac;
  
  var prf = new Prff(password),
      u, ui, i, j, k, out = [], b = sjcl.bitArray;

  for (k = 1; 32 * out.length < (length || 1); k++) {
    u = ui = prf.encrypt(b.concat(salt,[k]));
    
    for (i=1; i<count; i++) {
      ui = prf.encrypt(ui);
      for (j=0; j<ui.length; j++) {
        u[j] ^= ui[j];
      }
    }
    
    out = out.concat(u);
  }

  if (length) { out = b.clamp(out, length); }

  return out;
};
/** @fileOverview Random number generator.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 * @author Michael Brooks
 */

/** @constructor
 * @class Random number generator
 * @description
 * <b>Use sjcl.random as a singleton for this class!</b>
 * <p>
 * This random number generator is a derivative of Ferguson and Schneier's
 * generator Fortuna.  It collects entropy from various events into several
 * pools, implemented by streaming SHA-256 instances.  It differs from
 * ordinary Fortuna in a few ways, though.
 * </p>
 *
 * <p>
 * Most importantly, it has an entropy estimator.  This is present because
 * there is a strong conflict here between making the generator available
 * as soon as possible, and making sure that it doesn't "run on empty".
 * In Fortuna, there is a saved state file, and the system is likely to have
 * time to warm up.
 * </p>
 *
 * <p>
 * Second, because users are unlikely to stay on the page for very long,
 * and to speed startup time, the number of pools increases logarithmically:
 * a new pool is created when the previous one is actually used for a reseed.
 * This gives the same asymptotic guarantees as Fortuna, but gives more
 * entropy to early reseeds.
 * </p>
 *
 * <p>
 * The entire mechanism here feels pretty klunky.  Furthermore, there are
 * several improvements that should be made, including support for
 * dedicated cryptographic functions that may be present in some browsers;
 * state files in local storage; cookies containing randomness; etc.  So
 * look for improvements in future versions.
 * </p>
 */
sjcl.prng = function(defaultParanoia) {
  
  /* private */
  this._pools                   = [new sjcl.hash.sha256()];
  this._poolEntropy             = [0];
  this._reseedCount             = 0;
  this._robins                  = {};
  this._eventId                 = 0;
  
  this._collectorIds            = {};
  this._collectorIdNext         = 0;
  
  this._strength                = 0;
  this._poolStrength            = 0;
  this._nextReseed              = 0;
  this._key                     = [0,0,0,0,0,0,0,0];
  this._counter                 = [0,0,0,0];
  this._cipher                  = undefined;
  this._defaultParanoia         = defaultParanoia;
  
  /* event listener stuff */
  this._collectorsStarted       = false;
  this._callbacks               = {progress: {}, seeded: {}};
  this._callbackI               = 0;
  
  /* constants */
  this._NOT_READY               = 0;
  this._READY                   = 1;
  this._REQUIRES_RESEED         = 2;

  this._MAX_WORDS_PER_BURST     = 65536;
  this._PARANOIA_LEVELS         = [0,48,64,96,128,192,256,384,512,768,1024];
  this._MILLISECONDS_PER_RESEED = 30000;
  this._BITS_PER_RESEED         = 80;
};
 
sjcl.prng.prototype = {
  /** Generate several random words, and return them in an array.
   * A word consists of 32 bits (4 bytes)
   * @param {Number} nwords The number of words to generate.
   */
  randomWords: function (nwords, paranoia) {
    var out = [], i, readiness = this.isReady(paranoia), g;
  
    if (readiness === this._NOT_READY) {
      throw new sjcl.exception.notReady("generator isn't seeded");
    } else if (readiness & this._REQUIRES_RESEED) {
      this._reseedFromPools(!(readiness & this._READY));
    }
  
    for (i=0; i<nwords; i+= 4) {
      if ((i+1) % this._MAX_WORDS_PER_BURST === 0) {
        this._gate();
      }
   
      g = this._gen4words();
      out.push(g[0],g[1],g[2],g[3]);
    }
    this._gate();
  
    return out.slice(0,nwords);
  },
  
  setDefaultParanoia: function (paranoia, allowZeroParanoia) {
    if (paranoia === 0 && allowZeroParanoia !== "Setting paranoia=0 will ruin your security; use it only for testing") {
      throw "Setting paranoia=0 will ruin your security; use it only for testing";
    }

    this._defaultParanoia = paranoia;
  },
  
  /**
   * Add entropy to the pools.
   * @param data The entropic value.  Should be a 32-bit integer, array of 32-bit integers, or string
   * @param {Number} estimatedEntropy The estimated entropy of data, in bits
   * @param {String} source The source of the entropy, eg "mouse"
   */
  addEntropy: function (data, estimatedEntropy, source) {
    source = source || "user";
  
    var id,
      i, tmp,
      t = (new Date()).valueOf(),
      robin = this._robins[source],
      oldReady = this.isReady(), err = 0, objName;
      
    id = this._collectorIds[source];
    if (id === undefined) { id = this._collectorIds[source] = this._collectorIdNext ++; }
      
    if (robin === undefined) { robin = this._robins[source] = 0; }
    this._robins[source] = ( this._robins[source] + 1 ) % this._pools.length;
  
    switch(typeof(data)) {
      
    case "number":
      if (estimatedEntropy === undefined) {
        estimatedEntropy = 1;
      }
      this._pools[robin].update([id,this._eventId++,1,estimatedEntropy,t,1,data|0]);
      break;
      
    case "object":
      objName = Object.prototype.toString.call(data);
      if (objName === "[object Uint32Array]") {
        tmp = [];
        for (i = 0; i < data.length; i++) {
          tmp.push(data[i]);
        }
        data = tmp;
      } else {
        if (objName !== "[object Array]") {
          err = 1;
        }
        for (i=0; i<data.length && !err; i++) {
          if (typeof(data[i]) !== "number") {
            err = 1;
          }
        }
      }
      if (!err) {
        if (estimatedEntropy === undefined) {
          /* horrible entropy estimator */
          estimatedEntropy = 0;
          for (i=0; i<data.length; i++) {
            tmp= data[i];
            while (tmp>0) {
              estimatedEntropy++;
              tmp = tmp >>> 1;
            }
          }
        }
        this._pools[robin].update([id,this._eventId++,2,estimatedEntropy,t,data.length].concat(data));
      }
      break;
      
    case "string":
      if (estimatedEntropy === undefined) {
       /* English text has just over 1 bit per character of entropy.
        * But this might be HTML or something, and have far less
        * entropy than English...  Oh well, let's just say one bit.
        */
       estimatedEntropy = data.length;
      }
      this._pools[robin].update([id,this._eventId++,3,estimatedEntropy,t,data.length]);
      this._pools[robin].update(data);
      break;
      
    default:
      err=1;
    }
    if (err) {
      throw new sjcl.exception.bug("random: addEntropy only supports number, array of numbers or string");
    }
  
    /* record the new strength */
    this._poolEntropy[robin] += estimatedEntropy;
    this._poolStrength += estimatedEntropy;
  
    /* fire off events */
    if (oldReady === this._NOT_READY) {
      if (this.isReady() !== this._NOT_READY) {
        this._fireEvent("seeded", Math.max(this._strength, this._poolStrength));
      }
      this._fireEvent("progress", this.getProgress());
    }
  },
  
  /** Is the generator ready? */
  isReady: function (paranoia) {
    var entropyRequired = this._PARANOIA_LEVELS[ (paranoia !== undefined) ? paranoia : this._defaultParanoia ];
  
    if (this._strength && this._strength >= entropyRequired) {
      return (this._poolEntropy[0] > this._BITS_PER_RESEED && (new Date()).valueOf() > this._nextReseed) ?
        this._REQUIRES_RESEED | this._READY :
        this._READY;
    } else {
      return (this._poolStrength >= entropyRequired) ?
        this._REQUIRES_RESEED | this._NOT_READY :
        this._NOT_READY;
    }
  },
  
  /** Get the generator's progress toward readiness, as a fraction */
  getProgress: function (paranoia) {
    var entropyRequired = this._PARANOIA_LEVELS[ paranoia ? paranoia : this._defaultParanoia ];
  
    if (this._strength >= entropyRequired) {
      return 1.0;
    } else {
      return (this._poolStrength > entropyRequired) ?
        1.0 :
        this._poolStrength / entropyRequired;
    }
  },
  
  /** start the built-in entropy collectors */
  startCollectors: function () {
    if (this._collectorsStarted) { return; }
  
    this._eventListener = {
      loadTimeCollector: this._bind(this._loadTimeCollector),
      mouseCollector: this._bind(this._mouseCollector),
      keyboardCollector: this._bind(this._keyboardCollector),
      accelerometerCollector: this._bind(this._accelerometerCollector)
    }

    if (window.addEventListener) {
      window.addEventListener("load", this._eventListener.loadTimeCollector, false);
      window.addEventListener("mousemove", this._eventListener.mouseCollector, false);
      window.addEventListener("keypress", this._eventListener.keyboardCollector, false);
      window.addEventListener("devicemotion", this._eventListener.accelerometerCollector, false);
    } else if (document.attachEvent) {
      document.attachEvent("onload", this._eventListener.loadTimeCollector);
      document.attachEvent("onmousemove", this._eventListener.mouseCollector);
      document.attachEvent("keypress", this._eventListener.keyboardCollector);
    } else {
      throw new sjcl.exception.bug("can't attach event");
    }
  
    this._collectorsStarted = true;
  },
  
  /** stop the built-in entropy collectors */
  stopCollectors: function () {
    if (!this._collectorsStarted) { return; }
  
    if (window.removeEventListener) {
      window.removeEventListener("load", this._eventListener.loadTimeCollector, false);
      window.removeEventListener("mousemove", this._eventListener.mouseCollector, false);
      window.removeEventListener("keypress", this._eventListener.keyboardCollector, false);
      window.removeEventListener("devicemotion", this._eventListener.accelerometerCollector, false);
    } else if (document.detachEvent) {
      document.detachEvent("onload", this._eventListener.loadTimeCollector);
      document.detachEvent("onmousemove", this._eventListener.mouseCollector);
      document.detachEvent("keypress", this._eventListener.keyboardCollector);
    }

    this._collectorsStarted = false;
  },
  
  /* use a cookie to store entropy.
  useCookie: function (all_cookies) {
      throw new sjcl.exception.bug("random: useCookie is unimplemented");
  },*/
  
  /** add an event listener for progress or seeded-ness. */
  addEventListener: function (name, callback) {
    this._callbacks[name][this._callbackI++] = callback;
  },
  
  /** remove an event listener for progress or seeded-ness */
  removeEventListener: function (name, cb) {
    var i, j, cbs=this._callbacks[name], jsTemp=[];

    /* I'm not sure if this is necessary; in C++, iterating over a
     * collection and modifying it at the same time is a no-no.
     */

    for (j in cbs) {
      if (cbs.hasOwnProperty(j) && cbs[j] === cb) {
        jsTemp.push(j);
      }
    }

    for (i=0; i<jsTemp.length; i++) {
      j = jsTemp[i];
      delete cbs[j];
    }
  },
  
  _bind: function (func) {
    var that = this;
    return function () {
      func.apply(that, arguments);
    };
  },

  /** Generate 4 random words, no reseed, no gate.
   * @private
   */
  _gen4words: function () {
    for (var i=0; i<4; i++) {
      this._counter[i] = this._counter[i]+1 | 0;
      if (this._counter[i]) { break; }
    }
    return this._cipher.encrypt(this._counter);
  },
  
  /* Rekey the AES instance with itself after a request, or every _MAX_WORDS_PER_BURST words.
   * @private
   */
  _gate: function () {
    this._key = this._gen4words().concat(this._gen4words());
    this._cipher = new sjcl.cipher.aes(this._key);
  },
  
  /** Reseed the generator with the given words
   * @private
   */
  _reseed: function (seedWords) {
    this._key = sjcl.hash.sha256.hash(this._key.concat(seedWords));
    this._cipher = new sjcl.cipher.aes(this._key);
    for (var i=0; i<4; i++) {
      this._counter[i] = this._counter[i]+1 | 0;
      if (this._counter[i]) { break; }
    }
  },
  
  /** reseed the data from the entropy pools
   * @param full If set, use all the entropy pools in the reseed.
   */
  _reseedFromPools: function (full) {
    var reseedData = [], strength = 0, i;
  
    this._nextReseed = reseedData[0] =
      (new Date()).valueOf() + this._MILLISECONDS_PER_RESEED;
    
    for (i=0; i<16; i++) {
      /* On some browsers, this is cryptographically random.  So we might
       * as well toss it in the pot and stir...
       */
      reseedData.push(Math.random()*0x100000000|0);
    }
    
    for (i=0; i<this._pools.length; i++) {
     reseedData = reseedData.concat(this._pools[i].finalize());
     strength += this._poolEntropy[i];
     this._poolEntropy[i] = 0;
   
     if (!full && (this._reseedCount & (1<<i))) { break; }
    }
  
    /* if we used the last pool, push a new one onto the stack */
    if (this._reseedCount >= 1 << this._pools.length) {
     this._pools.push(new sjcl.hash.sha256());
     this._poolEntropy.push(0);
    }
  
    /* how strong was this reseed? */
    this._poolStrength -= strength;
    if (strength > this._strength) {
      this._strength = strength;
    }
  
    this._reseedCount ++;
    this._reseed(reseedData);
  },
  
  _keyboardCollector: function () {
    this._addCurrentTimeToEntropy(1);
  },
  
  _mouseCollector: function (ev) {
    var x = ev.x || ev.clientX || ev.offsetX || 0, y = ev.y || ev.clientY || ev.offsetY || 0;
    sjcl.random.addEntropy([x,y], 2, "mouse");
    this._addCurrentTimeToEntropy(0);
  },
  
  _loadTimeCollector: function () {
    this._addCurrentTimeToEntropy(2);
  },

  _addCurrentTimeToEntropy: function (estimatedEntropy) {
    if (window && window.performance && typeof window.performance.now === "function") {
      //how much entropy do we want to add here?
      sjcl.random.addEntropy(window.performance.now(), estimatedEntropy, "loadtime");
    } else {
      sjcl.random.addEntropy((new Date()).valueOf(), estimatedEntropy, "loadtime");
    }
  },
  _accelerometerCollector: function (ev) {
    var ac = ev.accelerationIncludingGravity.x||ev.accelerationIncludingGravity.y||ev.accelerationIncludingGravity.z;
    if(window.orientation){
      var or = window.orientation;
      if (typeof or === "number") {
        sjcl.random.addEntropy(or, 1, "accelerometer");
      }
    }
    if (ac) {
      sjcl.random.addEntropy(ac, 2, "accelerometer");
    }
    this._addCurrentTimeToEntropy(0);
  },

  _fireEvent: function (name, arg) {
    var j, cbs=sjcl.random._callbacks[name], cbsTemp=[];
    /* TODO: there is a race condition between removing collectors and firing them */

    /* I'm not sure if this is necessary; in C++, iterating over a
     * collection and modifying it at the same time is a no-no.
     */

    for (j in cbs) {
      if (cbs.hasOwnProperty(j)) {
        cbsTemp.push(cbs[j]);
      }
    }

    for (j=0; j<cbsTemp.length; j++) {
      cbsTemp[j](arg);
    }
  }
};

/** an instance for the prng.
* @see sjcl.prng
*/
sjcl.random = new sjcl.prng(6);

(function(){
  // function for getting nodejs crypto module. catches and ignores errors.
  function getCryptoModule() {
    try {
      return require('crypto');
    }
    catch (e) {
      return null;
    }
  }

  try {
    var buf, crypt, getRandomValues, ab;

    // get cryptographically strong entropy depending on runtime environment
    if (typeof module !== 'undefined' && module.exports && (crypt = getCryptoModule()) && crypt.randomBytes) {
      buf = crypt.randomBytes(1024/8);
      buf = new Uint32Array(new Uint8Array(buf).buffer);
      sjcl.random.addEntropy(buf, 1024, "crypto.randomBytes");

    } else if (window && Uint32Array) {
      ab = new Uint32Array(32);
      if (window.crypto && window.crypto.getRandomValues) {
        window.crypto.getRandomValues(ab);
      } else if (window.msCrypto && window.msCrypto.getRandomValues) {
        window.msCrypto.getRandomValues(ab);
      } else {
        return;
      }

      // get cryptographically strong entropy in Webkit
      sjcl.random.addEntropy(ab, 1024, "crypto.getRandomValues");

    } else {
      // no getRandomValues :-(
    }
  } catch (e) {
    if (typeof window !== 'undefined' && window.console) {
      console.log("There was an error collecting entropy from the browser:");
      console.log(e);
      //we do not want the library to fail due to randomness not being maintained.
    }
  }
}());
/** @fileOverview Convenince functions centered around JSON encapsulation.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */
 
 /** @namespace JSON encapsulation */
 sjcl.json = {
  /** Default values for encryption */
  defaults: { v:1, iter:1000, ks:128, ts:64, mode:"ccm", adata:"", cipher:"aes" },

  /** Simple encryption function.
   * @param {String|bitArray} password The password or key.
   * @param {String} plaintext The data to encrypt.
   * @param {Object} [params] The parameters including tag, iv and salt.
   * @param {Object} [rp] A returned version with filled-in parameters.
   * @return {Object} The cipher raw data.
   * @throws {sjcl.exception.invalid} if a parameter is invalid.
   */
  _encrypt: function (password, plaintext, params, rp) {
    params = params || {};
    rp = rp || {};

    var j = sjcl.json, p = j._add({ iv: sjcl.random.randomWords(4,0) },
                                  j.defaults), tmp, prp, adata;
    j._add(p, params);
    adata = p.adata;
    if (typeof p.salt === "string") {
      p.salt = sjcl.codec.base64.toBits(p.salt);
    }
    if (typeof p.iv === "string") {
      p.iv = sjcl.codec.base64.toBits(p.iv);
    }

    if (!sjcl.mode[p.mode] ||
        !sjcl.cipher[p.cipher] ||
        (typeof password === "string" && p.iter <= 100) ||
        (p.ts !== 64 && p.ts !== 96 && p.ts !== 128) ||
        (p.ks !== 128 && p.ks !== 192 && p.ks !== 256) ||
        (p.iv.length < 2 || p.iv.length > 4)) {
      throw new sjcl.exception.invalid("json encrypt: invalid parameters");
    }

    if (typeof password === "string") {
      tmp = sjcl.misc.cachedPbkdf2(password, p);
      password = tmp.key.slice(0,p.ks/32);
      p.salt = tmp.salt;
    } else if (sjcl.ecc && password instanceof sjcl.ecc.elGamal.publicKey) {
      tmp = password.kem();
      p.kemtag = tmp.tag;
      password = tmp.key.slice(0,p.ks/32);
    }
    if (typeof plaintext === "string") {
      plaintext = sjcl.codec.utf8String.toBits(plaintext);
    }
    if (typeof adata === "string") {
      adata = sjcl.codec.utf8String.toBits(adata);
    }
    prp = new sjcl.cipher[p.cipher](password);

    /* return the json data */
    j._add(rp, p);
    rp.key = password;

    /* do the encryption */
    p.ct = sjcl.mode[p.mode].encrypt(prp, plaintext, p.iv, adata, p.ts);

    //return j.encode(j._subtract(p, j.defaults));
    return p;
  },

  /** Simple encryption function.
   * @param {String|bitArray} password The password or key.
   * @param {String} plaintext The data to encrypt.
   * @param {Object} [params] The parameters including tag, iv and salt.
   * @param {Object} [rp] A returned version with filled-in parameters.
   * @return {String} The ciphertext serialized data.
   * @throws {sjcl.exception.invalid} if a parameter is invalid.
   */
  encrypt: function (password, plaintext, params, rp) {
    var j = sjcl.json, p = j._encrypt.apply(j, arguments);
    return j.encode(p);
  },

  /** Simple decryption function.
   * @param {String|bitArray} password The password or key.
   * @param {Object} ciphertext The cipher raw data to decrypt.
   * @param {Object} [params] Additional non-default parameters.
   * @param {Object} [rp] A returned object with filled parameters.
   * @return {String} The plaintext.
   * @throws {sjcl.exception.invalid} if a parameter is invalid.
   * @throws {sjcl.exception.corrupt} if the ciphertext is corrupt.
   */
  _decrypt: function (password, ciphertext, params, rp) {
    params = params || {};
    rp = rp || {};

    var j = sjcl.json, p = j._add(j._add(j._add({},j.defaults),ciphertext), params, true), ct, tmp, prp, adata=p.adata;
    if (typeof p.salt === "string") {
      p.salt = sjcl.codec.base64.toBits(p.salt);
    }
    if (typeof p.iv === "string") {
      p.iv = sjcl.codec.base64.toBits(p.iv);
    }

    if (!sjcl.mode[p.mode] ||
        !sjcl.cipher[p.cipher] ||
        (typeof password === "string" && p.iter <= 100) ||
        (p.ts !== 64 && p.ts !== 96 && p.ts !== 128) ||
        (p.ks !== 128 && p.ks !== 192 && p.ks !== 256) ||
        (!p.iv) ||
        (p.iv.length < 2 || p.iv.length > 4)) {
      throw new sjcl.exception.invalid("json decrypt: invalid parameters");
    }

    if (typeof password === "string") {
      tmp = sjcl.misc.cachedPbkdf2(password, p);
      password = tmp.key.slice(0,p.ks/32);
      p.salt  = tmp.salt;
    } else if (sjcl.ecc && password instanceof sjcl.ecc.elGamal.secretKey) {
      password = password.unkem(sjcl.codec.base64.toBits(p.kemtag)).slice(0,p.ks/32);
    }
    if (typeof adata === "string") {
      adata = sjcl.codec.utf8String.toBits(adata);
    }
    prp = new sjcl.cipher[p.cipher](password);

    /* do the decryption */
    ct = sjcl.mode[p.mode].decrypt(prp, p.ct, p.iv, adata, p.ts);

    /* return the json data */
    j._add(rp, p);
    rp.key = password;

    return sjcl.codec.utf8String.fromBits(ct);
  },

  /** Simple decryption function.
   * @param {String|bitArray} password The password or key.
   * @param {String} ciphertext The ciphertext to decrypt.
   * @param {Object} [params] Additional non-default parameters.
   * @param {Object} [rp] A returned object with filled parameters.
   * @return {String} The plaintext.
   * @throws {sjcl.exception.invalid} if a parameter is invalid.
   * @throws {sjcl.exception.corrupt} if the ciphertext is corrupt.
   */
  decrypt: function (password, ciphertext, params, rp) {
    var j = sjcl.json;
    return j._decrypt(password, j.decode(ciphertext), params, rp);
  },
  
  /** Encode a flat structure into a JSON string.
   * @param {Object} obj The structure to encode.
   * @return {String} A JSON string.
   * @throws {sjcl.exception.invalid} if obj has a non-alphanumeric property.
   * @throws {sjcl.exception.bug} if a parameter has an unsupported type.
   */
  encode: function (obj) {
    var i, out='{', comma='';
    for (i in obj) {
      if (obj.hasOwnProperty(i)) {
        if (!i.match(/^[a-z0-9]+$/i)) {
          throw new sjcl.exception.invalid("json encode: invalid property name");
        }
        out += comma + '"' + i + '":';
        comma = ',';

        switch (typeof obj[i]) {
          case 'number':
          case 'boolean':
            out += obj[i];
            break;

          case 'string':
            out += '"' + escape(obj[i]) + '"';
            break;

          case 'object':
            out += '"' + sjcl.codec.base64.fromBits(obj[i],0) + '"';
            break;

          default:
            throw new sjcl.exception.bug("json encode: unsupported type");
        }
      }
    }
    return out+'}';
  },
  
  /** Decode a simple (flat) JSON string into a structure.  The ciphertext,
   * adata, salt and iv will be base64-decoded.
   * @param {String} str The string.
   * @return {Object} The decoded structure.
   * @throws {sjcl.exception.invalid} if str isn't (simple) JSON.
   */
  decode: function (str) {
    str = str.replace(/\s/g,'');
    if (!str.match(/^\{.*\}$/)) { 
      throw new sjcl.exception.invalid("json decode: this isn't json!");
    }
    var a = str.replace(/^\{|\}$/g, '').split(/,/), out={}, i, m;
    for (i=0; i<a.length; i++) {
      if (!(m=a[i].match(/^(?:(["']?)([a-z][a-z0-9]*)\1):(?:(\d+)|"([a-z0-9+\/%*_.@=\-]*)")$/i))) {
        throw new sjcl.exception.invalid("json decode: this isn't json!");
      }
      if (m[3]) {
        out[m[2]] = parseInt(m[3],10);
      } else {
        out[m[2]] = m[2].match(/^(ct|salt|iv)$/) ? sjcl.codec.base64.toBits(m[4]) : unescape(m[4]);
      }
    }
    return out;
  },
  
  /** Insert all elements of src into target, modifying and returning target.
   * @param {Object} target The object to be modified.
   * @param {Object} src The object to pull data from.
   * @param {boolean} [requireSame=false] If true, throw an exception if any field of target differs from corresponding field of src.
   * @return {Object} target.
   * @private
   */
  _add: function (target, src, requireSame) {
    if (target === undefined) { target = {}; }
    if (src === undefined) { return target; }
    var i;
    for (i in src) {
      if (src.hasOwnProperty(i)) {
        if (requireSame && target[i] !== undefined && target[i] !== src[i]) {
          throw new sjcl.exception.invalid("required parameter overridden");
        }
        target[i] = src[i];
      }
    }
    return target;
  },
  
  /** Remove all elements of minus from plus.  Does not modify plus.
   * @private
   */
  _subtract: function (plus, minus) {
    var out = {}, i;

    for (i in plus) {
      if (plus.hasOwnProperty(i) && plus[i] !== minus[i]) {
        out[i] = plus[i];
      }
    }

    return out;
  },
  
  /** Return only the specified elements of src.
   * @private
   */
  _filter: function (src, filter) {
    var out = {}, i;
    for (i=0; i<filter.length; i++) {
      if (src[filter[i]] !== undefined) {
        out[filter[i]] = src[filter[i]];
      }
    }
    return out;
  }
};

/** Simple encryption function; convenient shorthand for sjcl.json.encrypt.
 * @param {String|bitArray} password The password or key.
 * @param {String} plaintext The data to encrypt.
 * @param {Object} [params] The parameters including tag, iv and salt.
 * @param {Object} [rp] A returned version with filled-in parameters.
 * @return {String} The ciphertext.
 */
sjcl.encrypt = sjcl.json.encrypt;

/** Simple decryption function; convenient shorthand for sjcl.json.decrypt.
 * @param {String|bitArray} password The password or key.
 * @param {String} ciphertext The ciphertext to decrypt.
 * @param {Object} [params] Additional non-default parameters.
 * @param {Object} [rp] A returned object with filled parameters.
 * @return {String} The plaintext.
 */
sjcl.decrypt = sjcl.json.decrypt;

/** The cache for cachedPbkdf2.
 * @private
 */
sjcl.misc._pbkdf2Cache = {};

/** Cached PBKDF2 key derivation.
 * @param {String} password The password.
 * @param {Object} [obj] The derivation params (iteration count and optional salt).
 * @return {Object} The derived data in key, the salt in salt.
 */
sjcl.misc.cachedPbkdf2 = function (password, obj) {
  var cache = sjcl.misc._pbkdf2Cache, c, cp, str, salt, iter;
  
  obj = obj || {};
  iter = obj.iter || 1000;
  
  /* open the cache for this password and iteration count */
  cp = cache[password] = cache[password] || {};
  c = cp[iter] = cp[iter] || { firstSalt: (obj.salt && obj.salt.length) ?
                     obj.salt.slice(0) : sjcl.random.randomWords(2,0) };
          
  salt = (obj.salt === undefined) ? c.firstSalt : obj.salt;
  
  c[salt] = c[salt] || sjcl.misc.pbkdf2(password, salt, obj.iter);
  return { key: c[salt].slice(0), salt:salt.slice(0) };
};