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   1  /*
   2    Copyright (c) 2003 Jan-Klaas Kollhof
   3    
   4    This file is part of the JavaScript o lait library(jsolait).
   5    
   6    jsolait is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU Lesser General Public License as published by
   8    the Free Software Foundation; either version 2.1 of the License, or
   9    (at your option) any later version.
  10   
  11    This software is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU Lesser General Public License for more details.
  15   
  16    You should have received a copy of the GNU Lesser General Public License
  17    along with this software; if not, write to the Free Software
  18    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */ 
  20  
  21  /**
  22      Cryptography module.
  23      Provides String encryption/decryption and hashing. 
  24  */
  25  Module("crypto", "0.1.2", function(mod){
  26      /**
  27          Returns all all available encrypters.
  28          @return  An array of encrypters names.
  29      */
  30      mod.listEncrypters=function(){
  31          var c=[];
  32          for(var attr in String.prototype){
  33              if(attr.slice(0, 8) == "encrypt_"){
  34                  c.push(attr.slice(8));
  35              }
  36          }
  37          return c;
  38      }
  39      /**
  40          Returns all all available decrypters.
  41          @return  An array of decrypters names.
  42      */
  43      mod.listDecrypters=function(){
  44          var c=[];
  45          for(var attr in String.prototype){
  46              if(attr.slice(0, 8) == "decrypt_"){
  47                  c.push(attr.slice(8));
  48              }
  49          }
  50          return c;
  51      }
  52      
  53      /**
  54          Encrypts a string.
  55          Parameters but the crypdec parameter are forwardet to the crypdec.
  56          @param codec  The codec to use.
  57      */
  58      String.prototype.encrypt=function(crydec){
  59          var n = "encrypt_" + crydec;
  60          if(String.prototype[n]){
  61              var args=[];
  62              for(var i=1;i<arguments.length;i++){
  63                  args[i-1] = arguments[i];
  64              }
  65              return String.prototype[n].apply(this, args);
  66          }else{
  67              throw new mod.Exception("Decrypter '%s' not found.".format(crydec));
  68          }
  69      }
  70      /**
  71          Decrypts a string.
  72          Parameters but the crypdec parameter are forwardet to the crypdec.
  73          @param codec  The codec to use.
  74      */
  75      String.prototype.decrypt=function(crydec){
  76          var n = "decrypt_" + crydec;
  77          if(String.prototype[n]){
  78              var args=[];
  79              for(var i=1;i<arguments.length;i++){
  80                  args[i-1] = arguments[i];
  81              }
  82              return String.prototype[n].apply(this, args);
  83          }else{
  84              throw new mod.Exception("Encrypter '%s' not found.".format(crydec));
  85          }
  86      }
  87      
  88      /**
  89          Encrypts a string using XOR.
  90          The whole String will be XORed with the key. 
  91          If the key is shorter than the String then it will be multiplied to fit the length of the String.
  92          @param key  The key to use for encryption.
  93      */
  94      String.prototype.encrypt_xor=function(key){
  95          var e=new Array(this.length);
  96          var l=key.length;
  97          for(var i=0;i<this.length;i++){
  98              e[i] = String.fromCharCode(this.charCodeAt(i) ^ key.charCodeAt(i % l));
  99          }
 100          return e.join("");
 101      }
 102      /**
 103          Decrypts a string using XOR.
 104          Since XORing is symetric it is the same as the encrypter.
 105          @param key  The key to use for decryption.
 106      */
 107      String.prototype.decrypt_xor=String.prototype.encrypt_xor;
 108      /**
 109          Encrypts a string using the ARC4 algorithm.
 110          @param key  The key to use for encryption.
 111      */
 112      String.prototype.encrypt_rc4=function(key){
 113          //generate substitution box
 114          var sbox = new Array (256);
 115          for (var i=0; i<256; i++){
 116               sbox[i]=i;
 117          }
 118          
 119          //swap things around 
 120          var j=0;
 121          for (var i=0; i < 256; i++) {
 122               j = (j + sbox[i] + key.charCodeAt(i % key.length)) % 256;
 123               var tmp = sbox[i];
 124               sbox[i] = sbox[j];
 125               sbox[j] = tmp;
 126          }
 127          
 128          //calculate the result
 129          var i=256;    
 130          var j=256;
 131          var rslt=new Array(this.length);
 132          for (var k=0; k < this.length; k++) {
 133              i = (i + 1) % 256;
 134              j = (j + sbox[i]) % 256;
 135              var tmp = sbox[i];
 136              sbox[i] = sbox[j];
 137              sbox[j] = tmp;
 138              t = (sbox[i] + sbox[j]) % 256;
 139              rslt[k] = String.fromCharCode(this.charCodeAt(k) ^ sbox[t]);
 140          }
 141          return rslt.join("");
 142      }
 143      /**
 144          Decrypts a string using the ARC4 algorithm.
 145          Since it is symetric it is the same as the encrypter.
 146          @param key  The key to use for decryption.
 147      */
 148      String.prototype.decrypt_rc4=String.prototype.encrypt_rc4;
 149  })