function decode64(input) {
	var output = new StringMaker();
	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, "");
 
	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.append(String.fromCharCode(chr1));
 
		if (enc3 != 64) {
			output.append(String.fromCharCode(chr2));
		}
		if (enc4 != 64) {
			output.append(String.fromCharCode(chr3));
		}
	}
 
	return output.toString();
}