Well I got this xor encryption and trying to turn it in more complicated.
Any suggestions?

Code:
public static string EncryptMessage(string inputMessage)
        {
            StringBuilder inputMsg = new StringBuilder(inputMessage);
            StringBuilder outputMsg = new StringBuilder(inputMessage.Length);
            byte xorKey = 0xAC;
            
            char c;
            for (int i = 0; i < inputMsg.Length; i++ )
            {
                c = inputMsg[i];
                c = (char)(c ^ xorKey);
                xorKey ^= (byte)((inputMsg.Length - 1)+i);
                outputMsg.Append(c);
            }
            return outputMsg.ToString();
        }