rxcipher.4.0.js

/**
 *  XORShiftPlus "non-linear" PRNG
 *  Author: k98kurz (@gmail)
 *  License: MIT
 *  Date: 2020-09-07
 *  Description: Based upon the xorshift128+ generator, one of the fastest generators passing BigCrush.
 *  Methods:
 *      next(n)         returns Uint32Array of n random numbers
 *      nextHex(n)      returns Array of n hexidecimal numbers
 *      bytes(n)        returns Uint8Array of n random bytes
 *      bytesHex(n)     returns Array of n random bytes in hexidecimal
 *      hex(n)          returns hexidecimal string of n bytes
 *  Note: This generates with higher periodicity and better random distribution than the linear XORShift.
 */
class XORShiftPlus {
  #booted = false;
  #x;
  #y;
  #z;
  #w;

  constructor (seed) {
    this.#x = new Uint32Array(1);
    this.#y = new Uint32Array(1);
    this.#z = new Uint32Array(1);
    this.#w = new Uint32Array(1);
    this.#x[0] = seed ? seed|0 : 317973455;
    this.#y[0] = this.#x[0]<<362436069;
    this.#z[0] = this.#y[0]+this.#x[0];
    this.#w[0] = this.#z[0]^this.#x[0]+this.#y[0];
  }

  #next () {
    let t = new Uint32Array(1);
    t[0] = this.#x[0]^(this.#x[0]<<11);
    this.#x[0] = this.#y[0];
    this.#y[0] = this.#z[0];
    this.#z[0] = this.#w[0];
    this.#w[0] = this.#w[0]^(this.#w[0]>>19)^(t[0]^(t[0]>>8));
    return this.#w[0]+this.#y[0];
  }

  #boot () {
    // if not booted, discard the first numbers as they are somewhat predictable
    if (this.#booted)
      return;
    for (let i=0, n=this.#next(), j=this.#next()%256; i<=j; this.#next(), ++i);
    this.#booted = true;
  }

  next (n, option) {
    this.#boot();
    n = (n === undefined || typeof n !== 'number') ? 1 : n;
    let t; n |= 0; n = n>0 ? n : 1;
    option = (option === undefined || typeof n !== 'number') ? 0 : option;

    // redundant code, but improved performance
    switch (option) {
      // nextHex
      case 1:
        t = [];
        for (let i=0, il=n; i<il; t[i++] = this.#next().toString(16));
        break;
      // bytes
      case 2:
        t = new Uint8Array(n);
        for (let i=0, il=n; i<il; t[i++] = this.#next());
        break;
      // bytesHex
      case 3:
        t = [];
        for (let i=0, il=n; i<il; t[i] = (this.#next()%256).toString(16), t[i] = t[i].length%2 ? '0'+t[i] : t[i], ++i);
        break;
      // hex
      case 4:
        t = [];
        for (let i=0, il=n; i<il; t[i] = (this.#next()%256).toString(16), t[i] = t[i].length%2 ? '0'+t[i] : t[i], ++i);
        t = t.join('');
        break;
      // next
      default:
        t = new Uint32Array(n);
        for (let i=0, il=n; i<il; t[i++] = this.#next());
    }
    return t;
  };

  nextHex (n) { return this.next(n, 1); };

  bytes (n) { return this.next(n, 2); };

  bytesHex (n) { return this.next(n, 3); };

  hex (n) { return this.next(n, 4); };
}

/**
 *  KeyStream
 *  Author: k98kurz
 *  License: MIT
 *  Date: 2020-09-07
 *  Description: Takes a key and iv, mixes them, and uses the result to seed several XORShiftPlus PRNGs.
 *  Dependency: XORShiftPlus
 *  Methods:
 *
 */
class KeyStream {
  #csprngs;
  #state;
  #keyLength;
  #keyIndex;
  #stateIndex;
  #workingByte = new Uint8Array(1);
  #key;
  #iv;

  constructor (key, iv) {
    if (typeof key == 'undefined')
      throw new Error('KeyStream: key required');
    if (typeof key == 'object' && key instanceof Array)
      key = (typeof key[0] == 'number') ? new Uint8Array(key) : key.join('');
    if (typeof key == 'string')
      key = KeyStream.toUTF8Array(key);
    if (typeof key !== 'object' && !(key instanceof Uint8Array))
      throw new Error('KeyStream: expected key of type String, Array, or Uint8Array');

    if (typeof iv == 'undefined')
      throw new Error('KeyStream: iv required');
    if (typeof iv == 'object' && iv instanceof Array)
      iv = (typeof iv[0] == 'number') ? new Uint8Array(iv) : iv.join('');
    if (typeof iv == 'string')
      iv = KeyStream.toUTF8Array(iv);
    if (!(iv instanceof Uint8Array) || iv.length == 0)
      throw new Error('KeyStream: expected iv of type String, Array or Uint8Array');

    // set the key and iv private properties
    this.#key = key;
    this.#iv = iv;

    // initialize some internal state
    this.#csprngs = []; this.#keyLength = this.#key.length; this.#keyIndex = 0; this.#state = new Uint8Array(64); this.#stateIndex = 0;
    for (let i = 0; i < this.#keyLength; i++) {
      this.#csprngs[i] = new XORShiftPlus(this.#key[i]);
    }
    for (let i = 0, j = 0, c = 0; c < this.#keyLength * 4; ++i, ++j, ++c) {
      j = (j == this.#keyLength) ? 0 : j;
      i = (i == this.#iv.length) ? 0 : i;
      this.#key[j] = this.#key[j] + this.#iv[i];
    }
    for (let i = 0, j = 0; i < 64; ++i, ++j) {
      j = (j == this.#keyLength) ? 0 : j;
      this.#state[i] = this.#csprngs[j].next()[0];
    }
    for (let i = 63, j = 0, t, m; i >= 0; --i, ++j) {
      j = (j == this.#keyLength) ? 0 : j;
      t = (this.#csprngs[j].next()[0] + this.#key[j]) % 64;
      m = this.#state[t];
      this.#state[t] = KeyStream.RXEncrypt(this.#state[i], this.#key[j], this.#workingByte);
      this.#state[i] = KeyStream.RXDecrypt(m, t, this.#workingByte);
    }
  }

  #next () {
    this.#keyIndex = (++this.#keyIndex == this.#keyLength) ? 0 : this.#keyIndex;
    this.#stateIndex = (++this.#stateIndex == 64) ? 0 : this.#stateIndex;
    this.#state[this.#stateIndex] = KeyStream.RXEncrypt(this.#state[this.#stateIndex], this.#key[this.#keyIndex], this.#workingByte);
    this.#state[63 - this.#stateIndex] = KeyStream.RXEncrypt(this.#state[63 - this.#stateIndex], this.#state[this.#stateIndex], this.#workingByte);
    return this.#state[this.#stateIndex];
  }

  getBytes (nBytes) {
    nBytes = (nBytes|0 ? nBytes|0 : (parseInt(nBytes) ? parseInt(nBytes) : 1));
    let k = new Uint8Array(nBytes);
    for (let o=0; o<nBytes; ++o) {
      k[o] = this.#next();
    }
    return k;
  }

  static RXEncrypt (t, k, workingByte) {
    workingByte[0] = (t+k);
    return workingByte[0]^k;
  }

  static RXDecrypt (c, k, workingByte) {
    workingByte[0] = (c^k) - k;
    return workingByte[0];
  }

  // convert from JavaScript's internal UTF-16 strings to UTF-8
  // ripped from http://stackoverflow.com/a/18729931
  // credit: Joni Salonen
  static toUTF8Array(str) {
    let utf8 = [], charcode;
    for (let i=0; i < str.length; i++) {
      charcode = str.charCodeAt(i);
      if (charcode < 0x80) utf8.push(charcode);
      else if (charcode < 0x800) {
        utf8.push(0xc0 | (charcode >> 6),
            0x80 | (charcode & 0x3f));
      } else if (charcode < 0xd800 || charcode >= 0xe000) {
        utf8.push(0xe0 | (charcode >> 12),
            0x80 | ((charcode>>6) & 0x3f),
            0x80 | (charcode & 0x3f));
      } else { // surrogate pair
        i++;
        // UTF-16 encodes 0x10000-0x10FFFF by
        // subtracting 0x10000 and splitting the
        // 20 bits of 0x0-0xFFFFF into two halves
        charcode = 0x10000 + (((charcode & 0x3ff)<<10)
            | (str.charCodeAt(i) & 0x3ff));
        utf8.push(0xf0 | (charcode >>18),
            0x80 | ((charcode>>12) & 0x3f),
            0x80 | ((charcode>>6) & 0x3f),
            0x80 | (charcode & 0x3f));
      }
    }
    return new Uint8Array(utf8);
  }
}

/**
 * Title:    RXCipher
 * Description:    Simple and relatively quick stream cipher algorithm - JavaScript implementation
 * Author:    Jonathan Voss
 * Date:    8/7/2012 (v1.0); 12/16/2014 (v2.0); 11/19/2015 (v3.0); 09/07/2020 (4.0)
 * Version:    4.0
 * Namespace:    pastebin.com/u/k98kurz; github.com/k98kurz
 * License:    ISC
 *
 * Basic byte-level algorithm
 * t = plaintext byte, c = ciphertext byte, k = encryption keystream byte
 *    function enc (t, k) { return (t+k>255 ? t+k-256 : t+k)^k; }
 *    function dec (c, k) { return (c^k)-k<0 ? (c^k)-k+256 : (c^k)-k; }
 *
 *
 * Class implementation
 * Instance Methods:
 *    encrypt ( plaintext )
 *      encrypts plaintext with key stream derived from skey
 *    decrypt ( ciphertext)
 *      decrypts ciphertext with key stream derived from skey
 *    getKeyStream ()
 *      returns a KeyStream for PRNG generation
 *    reset ()
 *      resets the internal KeyStream
 * Static Methods:
 *    rxencrypt ( key, plaintext, optional iv )
 *      creates ephemeral RXCipher instance, calls encrypt, and returns {iv}.{ciphertext}
 *    rxdecrypt ( key, ciphertextString )
 *      decrypts rxencrypt output
 *
 * Changes:
 *  2.0 (12/16/2014): added pseudo-random key stream; dropped automatic hex conversion of ciphertext
 *  2.1 (12/29/2014): changed default seed value for XORShiftPlus PRNG
 *  2.2 (11/18/2015): converts to/from UTF-8 encoding; new keystream uses multiple csprngs and XORs the key with csprng values
 *  2.3 (11/18/2015): added explicit IV support; made base RXEncrypt & RXDecrypt use a Uint8 byte
 *  3.0 (11/19/2015): changed KeyStream to use an internally mixed 64 byte state; improved IV handling; improved performance
 *  3.1 (02/01/2016): updated KeyStream to use improved/fixed XORShiftPlus class; encrypt/decrypt use hex; encryptRaw/decryptRaw use Uint8Array
 *  3.2 (03/08/2016): bug fix: getKeyStream now returns actual KeyStream; reset method returns this
 *  4.0 (09/07/2020): converted to es6 class; added static helper methods
*/
class RXCipher {
  #key;
  #iv;
  #stream;

  constructor (key, iv) {
    this.#key = (typeof key == 'object' && key instanceof Uint8Array) ? RXCipher.fromUTF8Array(key) : key;
    this.#iv = (typeof iv == 'object' && iv instanceof Uint8Array) ? RXCipher.fromUTF8Array(iv) : iv;
    this.#stream = new KeyStream(this.#key, this.#iv);
  }

  #encrypt (plaintext) {
    let ciphertext = new Uint8Array(plaintext.length);
    let key = this.#stream.getBytes(plaintext.length);
    for (let i = 0, ij = plaintext.length; i < ij; ++i) {
      ciphertext[i] = plaintext[i] ^ key[i];
    }
    return ciphertext;
  }

  #decrypt (ciphertext) {
    let plaintext = new Uint8Array(ciphertext.length);
    let key = this.#stream.getBytes(ciphertext.length);
    for (let i = 0, ij = ciphertext.length; i < ij; ++i) {
      plaintext[i] = ciphertext[i] ^ key[i];
    }
    return plaintext;
  }

  encrypt (plaintext) {
    let ciphertext = this.#encrypt(RXCipher.toUTF8Array(plaintext));
    return RXCipher.toHex(ciphertext);
  }

  decrypt (ciphertext) {
    let plaintext = this.#decrypt(RXCipher.fromHex(ciphertext));
    return RXCipher.fromUTF8Array(plaintext);
  }

  encryptRaw (plaintext) {
    return this.#encrypt(RXCipher.toUTF8Array(plaintext));
  }

  decryptRaw (ciphertext) {
    return RXCipher.fromUTF8Array(this.#decrypt(ciphertext));
  }

  static rxencrypt (key, plaintext, iv) {
    if (iv === undefined)
      iv = (new XORShiftPlus(Date.now())).bytes(8);

    let rxc = new RXCipher(key, iv);
    let ciphertext = rxc.encrypt(plaintext);

    return ciphertext + '.' + RXCipher.toHex(iv);
  }

  static rxdecrypt (key, ciphertextString) {
    let ctSplit = ciphertextString.split('.');
    let ciphertext = ctSplit[0];
    let iv = RXCipher.fromHex(ctSplit[1]);
    let rxc = new RXCipher(key, iv);

    return rxc.decrypt(ciphertext);
  }

  getKeyStream () {
    return new KeyStream(this.#key, this.#iv);
  }

  reset () {
    this.#stream = new KeyStream (this.#key, this.#iv);
    return this;
  }

  static RXEncrypt (t, k, workingByte) {
    workingByte[0] = (t+k);
    return workingByte[0]^k;
  }

  static RXDecrypt (c, k, workingByte) {
    workingByte[0] = (c^k) - k;
    return workingByte[0];
  }

  // convert from JavaScript's internal UTF-16 strings to UTF-8
  // ripped from http://stackoverflow.com/a/18729931
  // credit: Joni Salonen
  static toUTF8Array(str) {
    let utf8 = [], charcode;
    for (let i=0; i < str.length; i++) {
      charcode = str.charCodeAt(i);
      if (charcode < 0x80) utf8.push(charcode);
      else if (charcode < 0x800) {
        utf8.push(0xc0 | (charcode >> 6),
            0x80 | (charcode & 0x3f));
      } else if (charcode < 0xd800 || charcode >= 0xe000) {
        utf8.push(0xe0 | (charcode >> 12),
            0x80 | ((charcode>>6) & 0x3f),
            0x80 | (charcode & 0x3f));
      } else { // surrogate pair
        i++;
        // UTF-16 encodes 0x10000-0x10FFFF by
        // subtracting 0x10000 and splitting the
        // 20 bits of 0x0-0xFFFFF into two halves
        charcode = 0x10000 + (((charcode & 0x3ff)<<10)
            | (str.charCodeAt(i) & 0x3ff));
        utf8.push(0xf0 | (charcode >>18),
            0x80 | ((charcode>>12) & 0x3f),
            0x80 | ((charcode>>6) & 0x3f),
            0x80 | (charcode & 0x3f));
      }
    }
    return new Uint8Array(utf8);
  }

  // convert from UTF-8 to JavaScript's internal UTF-16 strings
  // ripped from https://github.com/coolaj86/TextEncoderLite
  // credit: AJ ONeal (coolaj86) && Feross Aboukhadijeh (feross)
  static fromUTF8Array (arr) {
    let utf16 = '', tmp = '';
    for (let i = 0, ij = arr.length; i < ij; i++) {
      if (arr[i] <= 0x7F) {
        utf16 += RXCipher.decodeUtf8Char(tmp) + String.fromCharCode(arr[i]);
        tmp = '';
      } else {
        tmp += '%' + arr[i].toString(16);
      }
    }

    return utf16 + RXCipher.decodeUtf8Char(tmp);
  }

  static decodeUtf8Char (str) {
    try {
      return decodeURIComponent(str);
    } catch (err) {
      return String.fromCharCode(0xFFFD); // UTF 8 invalid char
    }
  }

  static toHex (raw) {
    let t = [];
    for (let i=0, il=raw.length; i<il; ++i) {
        t[i] = raw[i].toString(16); t[i] = t[i].length%2 ? '0'+t[i] : t[i];
    }
    return t.join('');
  }

  static fromHex (hex) {
    let t = new Uint8Array(hex.length/2);
    for (let i=0, j=0, il=hex.length; i<il; ++i, ++j) {
        t[j] = parseInt(hex[i] + hex[++i], 16);
    }
    return t;
  }
}