wwwroot/js/rc4.js

   1 /* RC4 symmetric cipher encryption/decryption
   2  * Copyright (c) 2006 by Ali Farhadi.
   3  * released under the terms of the Gnu Public License.
   4  * see the GPL for details.
   5  *
   6  * Email: ali[at]farhadi[dot]ir
   7  * Website: http://farhadi.ir/
   8  */
   9
  10 /**
  11  * Encrypt given plain text using the key with RC4 algorithm.
  12  * All parameters and return value are in binary format.
  13  *
  14  * @param string key - secret key for encryption
  15  * @param string pt - plain text to be encrypted
  16  * @return string
  17  */
  18 function rc4Encrypt(key, pt) {
  19         s = new Array();
  20         for (var i=0; i<256; i++) {
  21                 s[i] = i;
  22         }
  23         var j = 0;
  24         var x;
  25         for (i=0; i<256; i++) {
  26                 j = (j + s[i] + key.charCodeAt(i % key.length)) % 256;
  27                 x = s[i];
  28                 s[i] = s[j];
  29                 s[j] = x;
  30         }
  31         i = 0;
  32         j = 0;
  33         var ct = '';
  34         for (var y=0; y<pt.length; y++) {
  35                 i = (i + 1) % 256;
  36                 j = (j + s[i]) % 256;
  37                 x = s[i];
  38                 s[i] = s[j];
  39                 s[j] = x;
  40                 ct += String.fromCharCode(pt.charCodeAt(y) ^ s[(s[i] + s[j]) % 256]);
  41         }
  42         return ct;
  43 }
  44
  45 /**
  46  * Decrypt given cipher text using the key with RC4 algorithm.
  47  * All parameters and return value are in binary format.
  48  *
  49  * @param string key - secret key for decryption
  50  * @param string ct - cipher text to be decrypted
  51  * @return string
  52 */
  53 function rc4Decrypt(key, ct) {
  54         return rc4Encrypt(key, ct);
  55 }