more progress :D

lib/Crypto.cs

@@ -1,11 +0,0 @@
-using System.Security.Cryptography;
-
-namespace lib;
-
-public static class Crypto {
-    public static RSA GenerateKey() {
-        return RSA.Create(512);
-    }
-
-
-}

lib/Request.cs

@@ -3,8 +3,31 @@
 public enum RequestType {
     Register = 1,
     ConfirmRegister = 2,
-    GetMessages = 3,
-    GetUserKey = 4,
-    SendMessage = 5,
-    SendAck = 6
+    Login = 3,
+    GetMessages = 4,
+    GetUserKey = 5,
+    SendMessage = 6,
+}
+
+public static class Request {
+    public static byte[] CreateRequest(RequestType Type, ref byte counter, byte[] data) {
+        if(data.Length > 13) {
+            throw new Exception("extra data is too long");
+        }
+
+        byte[] msg = new byte[128];
+        msg[0] = 0; // version
+        msg[1] = (byte)Type;
+        msg[2] = counter;
+        if(counter == byte.MaxValue) {
+            counter = 0;
+        }
+        else {
+            counter += 1;
+        }
+
+        // insert data 3..16
+        Array.Copy(data, 0, msg, 3, data.Length);
+        return msg;
+    }
 }