var keyStr = "ABCDEFGHIJKLMNOP" +
                "QRSTUVWXYZabcdef" +
                "ghijklmnopqrstuv" +
                "wxyz0123456789+/" +
                "=";

   function encode64(input) {
      var output = "";
      var chr1, chr2, chr3 = "";
      var enc1, enc2, enc3, enc4 = "";
      var i = 0;

      do {
         chr1 = input.charCodeAt(i++);
         chr2 = input.charCodeAt(i++);
         chr3 = input.charCodeAt(i++);

         enc1 = chr1 >> 2;
         enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
         enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
         enc4 = chr3 & 63;

         if (isNaN(chr2)) {
            enc3 = enc4 = 64;
         } else if (isNaN(chr3)) {
            enc4 = 64;
         }

         output = output + 
            keyStr.charAt(enc1) + 
            keyStr.charAt(enc2) + 
            keyStr.charAt(enc3) + 
            keyStr.charAt(enc4);
         chr1 = chr2 = chr3 = "";
         enc1 = enc2 = enc3 = enc4 = "";
      } while (i < input.length);

      return output;
   }

   function decode64(input) {
      var output = "";
      var chr1, chr2, chr3 = "";
      var enc1, enc2, enc3, enc4 = "";
      var i = 0;

      // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
      var base64test = /[^A-Za-z0-9\+\/\=]/g;
      //if (base64test.exec(input)) {
         //alert("There were invalid base64 characters in the input text.\n" +
         //      "Valid base64 characters are A-Z, a-z, 0-9, '+', '/', and '='\n" +
         //      "Expect errors in decoding.");
      //}
      input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

      do {
         enc1 = keyStr.indexOf(input.charAt(i++));
         enc2 = keyStr.indexOf(input.charAt(i++));
         enc3 = keyStr.indexOf(input.charAt(i++));
         enc4 = keyStr.indexOf(input.charAt(i++));

         chr1 = (enc1 << 2) | (enc2 >> 4);
         chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
         chr3 = ((enc3 & 3) << 6) | enc4;

         output = output + String.fromCharCode(chr1);

         if (enc3 != 64) {
            output = output + String.fromCharCode(chr2);
         }
         if (enc4 != 64) {
            output = output + String.fromCharCode(chr3);
         }

         chr1 = chr2 = chr3 = "";
         enc1 = enc2 = enc3 = enc4 = "";

      } while (i < input.length);

      return output;
   }
   
   
   /**
    * Read the JavaScript cookies tutorial at:
    *   http://www.netspade.com/articles/javascript/cookies.xml
    */
   
   /**
    * Sets a Cookie with the given name and value.
    *
    * name       Name of the cookie
    * value      Value of the cookie
    * [expires]  Expiration date of the cookie (default: end of current session)
    * [path]     Path where the cookie is valid (default: path of calling document)
    * [domain]   Domain where the cookie is valid
    *              (default: domain of calling document)
    * [secure]   Boolean value indicating if the cookie transmission requires a
    *              secure transmission
    */
   function setCookie(name, value, expires, path, domain, secure)
   {
       document.cookie= name + "=" + escape(value) +
           ((expires) ? "; expires=" + expires.toGMTString() : "") +
           ((path) ? "; path=" + path : "") +
           ((domain) ? "; domain=" + domain : "") +
           ((secure) ? "; secure" : "");
   }
   
   /**
    * Gets the value of the specified cookie.
    *
    * name  Name of the desired cookie.
    *
    * Returns a string containing value of specified cookie,
    *   or null if cookie does not exist.
    */
   function getCookie(name)
   {
       var dc = document.cookie;
       var prefix = name + "=";
       var begin = dc.indexOf("; " + prefix);
       if (begin == -1)
       {
           begin = dc.indexOf(prefix);
           if (begin != 0) return null;
       }
       else
       {
           begin += 2;
       }
       var end = document.cookie.indexOf(";", begin);
       if (end == -1)
       {
           end = dc.length;
       }
       return (dc.substring(begin + prefix.length, end));
   }
   
   /**
    * Deletes the specified cookie.
    *
    * name      name of the cookie
    * [path]    path of the cookie (must be same as path used to create cookie)
    * [domain]  domain of the cookie (must be same as domain used to create cookie)
    */
   function deleteCookie(name, path, domain)
   {
       if (getCookie(name))
       {
           document.cookie = name + "=" + 
               ((path) ? "; path=" + path : "") +
               ((domain) ? "; domain=" + domain : "") +
               "; expires=Thu, 01-Jan-70 00:00:01 GMT";
       }
   }