/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  AES implementation in JavaScript                     (c) Chris Veness 2005-2014 / MIT Licence */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/* jshint node:true *//* global define */


/**
 * AES (Rijndael cipher) encryption routines,
 *
 * Reference implementation of FIPS-197 http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf.
 *
 * @namespace
 */
var Aes = {};


/**
 * AES Cipher function: encrypt 'input' state with Rijndael algorithm [§5.1];
 *   applies Nr rounds (10/12/14) using key schedule w for 'add round key' stage.
 *
 * @param   {number[]}   input - 16-byte (128-bit) input state array.
 * @param   {number[][]} w - Key schedule as 2D byte-array (Nr+1 x Nb bytes).
 * @returns {number[]}   Encrypted output state array.
 */
Aes.cipher = function (input, w) {
  const Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
  const Nr = w.length / Nb - 1; // no of rounds: 10/12/14 for 128/192/256-bit keys

  let state = [[], [], [], []]; // initialise 4xNb byte-array 'state' with input [§3.4]
  for (var i = 0; i < 4 * Nb; i++) state[i % 4][Math.floor(i / 4)] = input[i];

  state = Aes.addRoundKey(state, w, 0, Nb);

  for (let round = 1; round < Nr; round++) {
    state = Aes.subBytes(state, Nb);
    state = Aes.shiftRows(state, Nb);
    state = Aes.mixColumns(state, Nb);
    state = Aes.addRoundKey(state, w, round, Nb);
  }

  state = Aes.subBytes(state, Nb);
  state = Aes.shiftRows(state, Nb);
  state = Aes.addRoundKey(state, w, Nr, Nb);

  const output = new Array(4 * Nb); // convert state to 1-d array before returning [§3.4]
  for (var i = 0; i < 4 * Nb; i++) output[i] = state[i % 4][Math.floor(i / 4)];

  return output;
};


/**
 * Perform key expansion to generate a key schedule from a cipher key [§5.2].
 *
 * @param   {number[]}   key - Cipher key as 16/24/32-byte array.
 * @returns {number[][]} Expanded key schedule as 2D byte-array (Nr+1 x Nb bytes).
 */
Aes.keyExpansion = function (key) {
  const Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
  const Nk = key.length / 4; // key length (in words): 4/6/8 for 128/192/256-bit keys
  const Nr = Nk + 6; // no of rounds: 10/12/14 for 128/192/256-bit keys

  const w = new Array(Nb * (Nr + 1));
  let temp = new Array(4);

  // initialise first Nk words of expanded key with cipher key
  for (var i = 0; i < Nk; i++) {
    const r = [key[4 * i], key[4 * i + 1], key[4 * i + 2], key[4 * i + 3]];
    w[i] = r;
  }

  // expand the key into the remainder of the schedule
  for (var i = Nk; i < (Nb * (Nr + 1)); i++) {
    w[i] = new Array(4);
    for (var t = 0; t < 4; t++) temp[t] = w[i - 1][t];
    // each Nk'th word has extra transformation
    if (i % Nk == 0) {
      temp = Aes.subWord(Aes.rotWord(temp));
      for (var t = 0; t < 4; t++) temp[t] ^= Aes.rCon[i / Nk][t];
    }
    // 256-bit key has subWord applied every 4th word
    else if (Nk > 6 && i % Nk == 4) {
      temp = Aes.subWord(temp);
    }
    // xor w[i] with w[i-1] and w[i-Nk]
    for (var t = 0; t < 4; t++) w[i][t] = w[i - Nk][t] ^ temp[t];
  }

  return w;
};


/**
 * Apply SBox to state S [§5.1.1]
 * @private
 */
Aes.subBytes = function (s, Nb) {
  for (let r = 0; r < 4; r++) {
    for (let c = 0; c < Nb; c++) s[r][c] = Aes.sBox[s[r][c]];
  }
  return s;
};


/**
 * Shift row r of state S left by r bytes [§5.1.2]
 * @private
 */
Aes.shiftRows = function (s, Nb) {
  const t = new Array(4);
  for (let r = 1; r < 4; r++) {
    for (var c = 0; c < 4; c++) t[c] = s[r][(c + r) % Nb]; // shift into temp copy
    for (var c = 0; c < 4; c++) s[r][c] = t[c]; // and copy back
  } // note that this will work for Nb=4,5,6, but not 7,8 (always 4 for AES):
  return s; // see asmaes.sourceforge.net/rijndael/rijndaelImplementation.pdf
};


/**
 * Combine bytes of each col of state S [§5.1.3]
 * @private
 */
Aes.mixColumns = function (s, Nb) {
  for (let c = 0; c < 4; c++) {
    const a = new Array(4); // 'a' is a copy of the current column from 's'
    const b = new Array(4); // 'b' is a•{02} in GF(2^8)
    for (let i = 0; i < 4; i++) {
      a[i] = s[i][c];
      b[i] = s[i][c] & 0x80 ? s[i][c] << 1 ^ 0x011b : s[i][c] << 1;
    }
    // a[n] ^ b[n] is a•{03} in GF(2^8)
    s[0][c] = b[0] ^ a[1] ^ b[1] ^ a[2] ^ a[3]; // {02}•a0 + {03}•a1 + a2 + a3
    s[1][c] = a[0] ^ b[1] ^ a[2] ^ b[2] ^ a[3]; // a0 • {02}•a1 + {03}•a2 + a3
    s[2][c] = a[0] ^ a[1] ^ b[2] ^ a[3] ^ b[3]; // a0 + a1 + {02}•a2 + {03}•a3
    s[3][c] = a[0] ^ b[0] ^ a[1] ^ a[2] ^ b[3]; // {03}•a0 + a1 + a2 + {02}•a3
  }
  return s;
};


/**
 * Xor Round Key into state S [§5.1.4]
 * @private
 */
Aes.addRoundKey = function (state, w, rnd, Nb) {
  for (let r = 0; r < 4; r++) {
    for (let c = 0; c < Nb; c++) state[r][c] ^= w[rnd * 4 + c][r];
  }
  return state;
};


/**
 * Apply SBox to 4-byte word w
 * @private
 */
Aes.subWord = function (w) {
  for (let i = 0; i < 4; i++) w[i] = Aes.sBox[w[i]];
  return w;
};


/**
 * Rotate 4-byte word w left by one byte
 * @private
 */
Aes.rotWord = function (w) {
  const tmp = w[0];
  for (let i = 0; i < 3; i++) w[i] = w[i + 1];
  w[3] = tmp;
  return w;
};


// sBox is pre-computed multiplicative inverse in GF(2^8) used in subBytes and keyExpansion [§5.1.1]
Aes.sBox = [0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
  0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
  0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
  0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
  0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
  0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
  0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
  0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
  0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
  0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
  0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
  0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
  0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
  0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
  0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
  0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16];


// rCon is Round Constant used for the Key Expansion [1st col is 2^(r-1) in GF(2^8)] [§5.2]
Aes.rCon = [[0x00, 0x00, 0x00, 0x00],
  [0x01, 0x00, 0x00, 0x00],
  [0x02, 0x00, 0x00, 0x00],
  [0x04, 0x00, 0x00, 0x00],
  [0x08, 0x00, 0x00, 0x00],
  [0x10, 0x00, 0x00, 0x00],
  [0x20, 0x00, 0x00, 0x00],
  [0x40, 0x00, 0x00, 0x00],
  [0x80, 0x00, 0x00, 0x00],
  [0x1b, 0x00, 0x00, 0x00],
  [0x36, 0x00, 0x00, 0x00]];


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
if (typeof module !== 'undefined' && module.exports) module.exports = Aes; // CommonJs export
if (typeof define === 'function' && define.amd) define([], () => Aes); // AMD


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  AES Counter-mode implementation in JavaScript       (c) Chris Veness 2005-2014 / MIT Licence  */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/* jshint node:true *//* global define, escape, unescape, btoa, atob */
'use strict';
if (typeof module !== 'undefined' && module.exports) var Aes = require('./aes'); // CommonJS (Node.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.
 * @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); // encr: 'lwGl66VVwVObKIr6of8HVqJr'
 */
Aes.Ctr.encrypt = function (plaintext, password, nBits) {
  const blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
  if (!(nBits == 128 || nBits == 192 || nBits == 256)) return ''; // standard allows 128/192/256 bit keys
  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)
  const nBytes = nBits / 8; // no bytes in key (16/24/32)
  const pwBytes = new Array(nBytes);
  for (var i = 0; i < nBytes; i++) { // use 1st 16/24/32 chars of password for key
    pwBytes[i] = isNaN(password.charCodeAt(i)) ? 0 : password.charCodeAt(i);
  }
  let 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
  const counterBlock = new Array(blockSize);

  const nonce = (new Date()).getTime(); // timestamp: milliseconds since 1-Jan-1970
  const nonceMs = nonce % 1000;
  const nonceSec = Math.floor(nonce / 1000);
  const 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
  let 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
  const keySchedule = Aes.keyExpansion(key);

  const blockCount = Math.ceil(plaintext.length / blockSize);
  const ciphertxt = new Array(blockCount); // ciphertext as array of strings

  for (let 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);

    const cipherCntr = Aes.cipher(counterBlock, keySchedule); // -- encrypt counter block --

    // block size is reduced on final block
    const blockLength = b < blockCount - 1 ? blockSize : (plaintext.length - 1) % blockSize + 1;
    const 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]);
    }
    ciphertxt[b] = cipherChar.join('');
  }

  // use Array.join() for better performance than repeated string appends
  let ciphertext = ctrTxt + ciphertxt.join('');
  ciphertext = ciphertext.base64Encode();

  return ciphertext;
};


/**
 * Decrypt a text encrypted by AES in counter mode of operation
 *
 * @param   {string} ciphertext - Source text to be encrypted.
 * @param   {string} password - Password to use to generate a key.
 * @param   {number} nBits - Number of bits to be used in the key; 128 / 192 / 256.
 * @returns {string} Decrypted text
 *
 * @example
 *   var decr = Aes.Ctr.encrypt('lwGl66VVwVObKIr6of8HVqJr', 'pāşšŵōřđ', 256); // decr: 'big secret'
 */
Aes.Ctr.decrypt = function (ciphertext, password, nBits) {
  const blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
  if (!(nBits == 128 || nBits == 192 || nBits == 256)) return ''; // standard allows 128/192/256 bit keys
  ciphertext = String(ciphertext).base64Decode();
  password = String(password).utf8Encode();

  // use AES to encrypt password (mirroring encrypt routine)
  const nBytes = nBits / 8; // no bytes in key
  const pwBytes = new Array(nBytes);
  for (var i = 0; i < nBytes; i++) {
    pwBytes[i] = isNaN(password.charCodeAt(i)) ? 0 : password.charCodeAt(i);
  }
  let 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
  const counterBlock = new Array(8);
  const ctrTxt = ciphertext.slice(0, 8);
  for (var i = 0; i < 8; i++) counterBlock[i] = ctrTxt.charCodeAt(i);

  // generate key schedule
  const keySchedule = Aes.keyExpansion(key);

  // separate ciphertext into blocks (skipping past initial 8 bytes)
  const nBlocks = Math.ceil((ciphertext.length - 8) / blockSize);
  const 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
  const plaintxt = new Array(ciphertext.length);

  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;

    const cipherCntr = Aes.cipher(counterBlock, keySchedule); // encrypt counter block

    const plaintxtByte = new Array(ciphertext[b].length);
    for (var i = 0; i < ciphertext[b].length; i++) {
      // -- xor plaintxt with ciphered counter byte-by-byte --
      plaintxtByte[i] = cipherCntr[i] ^ ciphertext[b].charCodeAt(i);
      plaintxtByte[i] = String.fromCharCode(plaintxtByte[i]);
    }
    plaintxt[b] = plaintxtByte.join('');
  }

  // join array of blocks into single plaintext string
  let plaintext = plaintxt.join('');
  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 */
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: 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, 'utf8').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('utf8'); // Node.js
    throw new Error('No Base64 Decode');
  };
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
if (typeof module !== 'undefined' && module.exports) module.exports = Aes.Ctr; // CommonJs export
if (typeof define === 'function' && define.amd) define(['Aes'], () => Aes.Ctr); // AMD


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  Encrypt/decrypt files                                                                         */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

function encryptFile(file) {
  // use FileReader.readAsArrayBuffer to handle binary files
  const reader = new FileReader();
  reader.readAsArrayBuffer(file);
  reader.onload = function (evt) {
    $('body').css({ cursor: 'wait' });

    // Aes.Ctr.encrypt expects a string, but converting binary file directly to string could
    // give invalid Unicode sequences, so convert bytestream ArrayBuffer to single-byte chars
    const contentBytes = new Uint8Array(reader.result); // ≡ evt.target.result
    let contentStr = '';
    for (let i = 0; i < contentBytes.length; i++) {
      contentStr += String.fromCharCode(contentBytes[i]);
    }

    const password = $('#password-file').val();

    const t1 = new Date();
    const ciphertext = Aes.Ctr.encrypt(contentStr, password, 256);
    const t2 = new Date();

    // use Blob to save encrypted file
    const blob = new Blob([ciphertext], { type: 'text/plain' });
    const filename = `${file.name}.encrypted`;
    saveAs(blob, filename);

    $('#encrypt-file-time').html(`${(t2 - t1) / 1000}s`); // display time taken
    $('body').css({ cursor: 'default' });
  };
}

function decryptFile(file) {
  // use FileReader.ReadAsText to read (base64-encoded) ciphertext file
  const reader = new FileReader();
  reader.readAsText(file);
  reader.onload = function (evt) {
    $('body').css({ cursor: 'wait' });

    const content = reader.result; // ≡ evt.target.result
    const password = $('#password-file').val();

    const t1 = new Date();
    const plaintext = Aes.Ctr.decrypt(content, password, 256);
    const t2 = new Date();

    // convert single-byte character stream to ArrayBuffer bytestream
    const contentBytes = new Uint8Array(plaintext.length);
    for (let i = 0; i < plaintext.length; i++) {
      contentBytes[i] = plaintext.charCodeAt(i);
    }

    // use Blob to save decrypted file
    const blob = new Blob([contentBytes], { type: 'application/octet-stream' });
    const filename = `${file.name.replace(/\.encrypted$/, '')}.decrypted`;
    saveAs(blob, filename);

    $('#decrypt-file-time').html(`${(t2 - t1) / 1000}s`); // display time taken
    $('body').css({ cursor: 'default' });
  };
}

export default Aes;