var base64s = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabc'+
              'defghijklmnopqrstuvwxyz0123456789+/';

function decode(encStr)
{
 var bits;
 var decOut = '';
 var i = 0;
 for(; i<encStr.length; i += 4)
 {
 bits = (base64s.indexOf(encStr.charAt(i)) & 0xff) <<18 |
 (base64s.indexOf(encStr.charAt(i +1)) & 0xff) <<12 |
 (base64s.indexOf(encStr.charAt(i +2)) & 0xff) << 6 |
 base64s.indexOf(encStr.charAt(i +3)) & 0xff;
 decOut += String.fromCharCode((bits & 0xff0000) >>16, (bits & 0xff00) >>8, bits & 0xff);
 }
 if(encStr.charCodeAt(i -2) == 61)
 {
 return(decOut.substring(0, decOut.length -2));
 }
 else if(encStr.charCodeAt(i -1) == 61)
 {
 return(decOut.substring(0, decOut.length -1));
 }
 else {return(decOut)};
}