function base64_decode( data ) 
{
	var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
	var o1, o2, o3, h1, h2, h3, h4, bits, i=0, enc='';
 
	do 
	{  
		// unpack four hexets into three octets using index points in b64
		
		h1 = b64.indexOf(data.charAt(i++));
		h2 = b64.indexOf(data.charAt(i++));
		h3 = b64.indexOf(data.charAt(i++));
		h4 = b64.indexOf(data.charAt(i++));
 
		bits = h1<<18 | h2<<12 | h3<<6 | h4;
 
		o1 = bits>>16 & 0xff;
		o2 = bits>>8 & 0xff;
		o3 = bits & 0xff;
 
		if (h3 == 64)      enc += String.fromCharCode(o1);
		else if (h4 == 64) enc += String.fromCharCode(o1, o2);
		else               enc += String.fromCharCode(o1, o2, o3);
	} 
	while ( i < data.length );
 
	return enc;
}