text: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
  /*  AES counter-mode (CTR) implementation in JavaScript               (c) Chris Veness 2005-2016  */
  /*                                                                                   MIT Licence  */
  /* www.movable-type.co.uk/scripts/aes.html                                                        */
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
  
  /* eslint no-redeclare: 0 *//* global WorkerGlobalScope */
  'use strict';
  if (typeof module!='undefined' && module.exports) var Aes = require('./aes.js'); // ≡ import Aes from 'aes.js'
  
  
  /**
   * Aes.Ctr: Counter-mode (CTR) wrapper for AES.
   *
   * This encrypts a Unicode string to produces a base64 ciphertext using 128/192/256-bit AES,
   * and the converse to decrypt an encrypted ciphertext.
   *
   * See http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
   *
   * @augments Aes
   */
  Aes.Ctr = {};
  
  
  /**
   * Encrypt a text using AES encryption in Counter mode of operation.
   *
   * Unicode multi-byte character safe
   *
   * @param   {string} plaintext - Source text to be encrypted.
   * @param   {string} password - The password to use to generate a key for encryption.
   * @param   {number} nBits - Number of bits to be used in the key; 128 / 192 / 256.
   * @returns {string} Encrypted text.
   *
   * @example
   *   var encr = Aes.Ctr.encrypt('big secret', 'pāşšŵōřđ', 256); // 'lwGl66VVwVObKIr6of8HVqJr'
   */
  Aes.Ctr.encrypt = function(plaintext, password, nBits) {
      var blockSize = 16;  // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
      if (!(nBits==128 || nBits==192 || nBits==256)) throw new Error('Key size is not 128 / 192 / 256');
      plaintext = String(plaintext).utf8Encode();
      password = String(password).utf8Encode();
  
      // use AES itself to encrypt password to get cipher key (using plain password as source for key
      // expansion) - gives us well encrypted key (though hashed key might be preferred for prod'n use)
      var nBytes = nBits/8;  // no bytes in key (16/24/32)
      var pwBytes = new Array(nBytes);
      for (var i=0; i<nBytes; i++) {  // use 1st 16/24/32 chars of password for key
          pwBytes[i] = i<password.length ?  password.charCodeAt(i) : 0;
      }
      var key = Aes.cipher(pwBytes, Aes.keyExpansion(pwBytes)); // gives us 16-byte key
      key = key.concat(key.slice(0, nBytes-16));  // expand key to 16/24/32 bytes long
  
      // initialise 1st 8 bytes of counter block with nonce (NIST SP800-38A §B.2): [0-1] = millisec,
      // [2-3] = random, [4-7] = seconds, together giving full sub-millisec uniqueness up to Feb 2106
      var counterBlock = new Array(blockSize);
  
      var nonce = (new Date()).getTime();  // timestamp: milliseconds since 1-Jan-1970
      var nonceMs = nonce%1000;
      var nonceSec = Math.floor(nonce/1000);
      var nonceRnd = Math.floor(Math.random()*0xffff);
      // for debugging: nonce = nonceMs = nonceSec = nonceRnd = 0;
  
      for (var i=0; i<2; i++) counterBlock[i]   = (nonceMs  >>> i*8) & 0xff;
      for (var i=0; i<2; i++) counterBlock[i+2] = (nonceRnd >>> i*8) & 0xff;
      for (var i=0; i<4; i++) counterBlock[i+4] = (nonceSec >>> i*8) & 0xff;
  
      // and convert it to a string to go on the front of the ciphertext
      var ctrTxt = '';
      for (var i=0; i<8; i++) ctrTxt += String.fromCharCode(counterBlock[i]);
  
      // generate key schedule - an expansion of the key into distinct Key Rounds for each round
      var keySchedule = Aes.keyExpansion(key);
  
      var blockCount = Math.ceil(plaintext.length/blockSize);
      var ciphertext = '';
  
      for (var b=0; b<blockCount; b++) {
          // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
          // done in two stages for 32-bit ops: using two words allows us to go past 2^32 blocks (68GB)
          for (var c=0; c<4; c++) counterBlock[15-c] = (b >>> c*8) & 0xff;
          for (var c=0; c<4; c++) counterBlock[15-c-4] = (b/0x100000000 >>> c*8);
  
          var cipherCntr = Aes.cipher(counterBlock, keySchedule);  // -- encrypt counter block --
  
          // block size is reduced on final block
          var blockLength = b<blockCount-1 ? blockSize : (plaintext.length-1)%blockSize+1;
          var cipherChar = new Array(blockLength);
  
          for (var i=0; i<blockLength; i++) {
              // -- xor plaintext with ciphered counter char-by-char --
              cipherChar[i] = cipherCntr[i] ^ plaintext.charCodeAt(b*blockSize+i);
              cipherChar[i] = String.fromCharCode(cipherChar[i]);
          }
          ciphertext += cipherChar.join('');
  
          // if within web worker, announce progress every 1000 blocks (roughly every 50ms)
          if (typeof WorkerGlobalScope != 'undefined' && self instanceof WorkerGlobalScope) {
              if (b%1000 == 0) self.postMessage({ progress: b/blockCount });
          }
      }
  
      ciphertext =  (ctrTxt+ciphertext).base64Encode();
  
      return ciphertext;
  };
  
  
  /**
   * Decrypt a text encrypted by AES in counter mode of operation
   *
   * @param   {string} ciphertext - Cipher text to be decrypted.
   * @param   {string} password - Password to use to generate a key for decryption.
   * @param   {number} nBits - Number of bits to be used in the key; 128 / 192 / 256.
   * @returns {string} Decrypted text
   *
   * @example
   *   var decr = Aes.Ctr.decrypt('lwGl66VVwVObKIr6of8HVqJr', 'pāşšŵōřđ', 256); // 'big secret'
   */
  Aes.Ctr.decrypt = function(ciphertext, password, nBits) {
      var blockSize = 16;  // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
      if (!(nBits==128 || nBits==192 || nBits==256)) throw new Error('Key size is not 128 / 192 / 256');
      ciphertext = String(ciphertext).base64Decode();
      password = String(password).utf8Encode();
  
      // use AES to encrypt password (mirroring encrypt routine)
      var nBytes = nBits/8;  // no bytes in key
      var pwBytes = new Array(nBytes);
      for (var i=0; i<nBytes; i++) {
          pwBytes[i] = i<password.length ?  password.charCodeAt(i) : 0;
      }
      var key = Aes.cipher(pwBytes, Aes.keyExpansion(pwBytes));
      key = key.concat(key.slice(0, nBytes-16));  // expand key to 16/24/32 bytes long
  
      // recover nonce from 1st 8 bytes of ciphertext
      var counterBlock = new Array(8);
      var ctrTxt = ciphertext.slice(0, 8);
      for (var i=0; i<8; i++) counterBlock[i] = ctrTxt.charCodeAt(i);
  
      // generate key schedule
      var keySchedule = Aes.keyExpansion(key);
  
      // separate ciphertext into blocks (skipping past initial 8 bytes)
      var nBlocks = Math.ceil((ciphertext.length-8) / blockSize);
      var ct = new Array(nBlocks);
      for (var b=0; b<nBlocks; b++) ct[b] = ciphertext.slice(8+b*blockSize, 8+b*blockSize+blockSize);
      ciphertext = ct;  // ciphertext is now array of block-length strings
  
      // plaintext will get generated block-by-block into array of block-length strings
      var plaintext = '';
  
      for (var b=0; b<nBlocks; b++) {
          // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
          for (var c=0; c<4; c++) counterBlock[15-c] = ((b) >>> c*8) & 0xff;
          for (var c=0; c<4; c++) counterBlock[15-c-4] = (((b+1)/0x100000000-1) >>> c*8) & 0xff;
  
          var cipherCntr = Aes.cipher(counterBlock, keySchedule);  // encrypt counter block
  
          var plaintxtByte = new Array(ciphertext[b].length);
          for (var i=0; i<ciphertext[b].length; i++) {
              // -- xor plaintext with ciphered counter byte-by-byte --
              plaintxtByte[i] = cipherCntr[i] ^ ciphertext[b].charCodeAt(i);
              plaintxtByte[i] = String.fromCharCode(plaintxtByte[i]);
          }
          plaintext += plaintxtByte.join('');
  
          // if within web worker, announce progress every 1000 blocks (roughly every 50ms)
          if (typeof WorkerGlobalScope != 'undefined' && self instanceof WorkerGlobalScope) {
              if (b%1000 == 0) self.postMessage({ progress: b/nBlocks });
          }
      }
  
      plaintext = plaintext.utf8Decode();  // decode from UTF8 back to Unicode multi-byte chars
  
      return plaintext;
  };
  
  
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
  
  /* Extend String object with method to encode multi-byte string to utf8
   * - monsur.hossa.in/2012/07/20/utf-8-in-javascript.html
   * - note utf8Encode is an identity function with 7-bit ascii strings, but not with 8-bit strings;
   * - utf8Encode('x') = 'x', but utf8Encode('ça') = 'Ã§a', and utf8Encode('Ã§a') = 'ÃÂ§a'*/
  if (typeof String.prototype.utf8Encode == 'undefined') {
      String.prototype.utf8Encode = function() {
          return unescape( encodeURIComponent( this ) );
      };
  }
  
  /* Extend String object with method to decode utf8 string to multi-byte */
  if (typeof String.prototype.utf8Decode == 'undefined') {
      String.prototype.utf8Decode = function() {
          try {
              return decodeURIComponent( escape( this ) );
          } catch (e) {
              return this; // invalid UTF-8? return as-is
          }
      };
  }
  
  /* Extend String object with method to encode base64
   * - developer.mozilla.org/en-US/docs/Web/API/window.btoa, nodejs.org/api/buffer.html
   * - note: btoa & Buffer/binary work on single-byte Unicode (C0/C1), so ok for utf8 strings, not for general Unicode...
   * - note: if btoa()/atob() are not available (eg IE9-), try github.com/davidchambers/Base64.js */
  if (typeof String.prototype.base64Encode == 'undefined') {
      String.prototype.base64Encode = function() {
          if (typeof btoa != 'undefined') return btoa(this); // browser
          if (typeof Buffer != 'undefined') return new Buffer(this, 'binary').toString('base64'); // Node.js
          throw new Error('No Base64 Encode');
      };
  }
  
  /* Extend String object with method to decode base64 */
  if (typeof String.prototype.base64Decode == 'undefined') {
      String.prototype.base64Decode = function() {
          if (typeof atob != 'undefined') return atob(this); // browser
          if (typeof Buffer != 'undefined') return new Buffer(this, 'base64').toString('binary'); // Node.js
          throw new Error('No Base64 Decode');
      };
  }
  
  
  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
  if (typeof module != 'undefined' && module.exports) module.exports = Aes.Ctr; // ≡ export default Aes.Ctr