function base64_decode(input) {
    var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    var output = "";
    var chr1, chr2, chr3;
    var enc1, enc2, enc3, enc4;
    var i = 0;
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
    while (i < input.length) {
	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);
	}
    }
    var utf8_decode = function (utftext) {
	var string = "";
	var i = 0;
	var c = c1 = c2 = 0;
	while ( i < utftext.length ) {
	      c = utftext.charCodeAt(i);
	      if (c < 128) {
		  string += String.fromCharCode(c);
		  i++;
	      } else if((c > 191) && (c < 224)) {
		  c2 = utftext.charCodeAt(i+1);
		  string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
		  i += 2;
	      } else {
		  c2 = utftext.charCodeAt(i+1);
		  c3 = utftext.charCodeAt(i+2);
		  string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
		  i += 3;
	      }
	}
	return string;
    }
    output = utf8_decode(output);
    return output;
}