var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
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 =
	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);
	  }
	} while (i < input.length);
	return output;
}