diff --git a/src/main/java/dslab/client/MessageClient.java b/src/main/java/dslab/client/MessageClient.java
index 620acb7..102ca2e 100644
--- a/src/main/java/dslab/client/MessageClient.java
+++ b/src/main/java/dslab/client/MessageClient.java
@@ -174,26 +174,28 @@ public class MessageClient implements IMessageClient, Runnable {
         IvParameterSpec iv = generateIv();
         // Save AES cipher for subsequent communication
         setAesCipher(secretKeySpec, iv);
-        // Concatenate challenge, secretKey and IV
-        byte[] concatenated = new byte[80];
-        System.arraycopy(clearTextChallenge, 0, concatenated, 0, 32);
-        System.arraycopy(secretKeySpec.getEncoded(), 0, concatenated, 32, 32);
-        System.arraycopy(iv.getIV(), 0, concatenated, 64, 16);
-        String base64Encoded = Base64.getEncoder().encodeToString(concatenated);
-        // Encrypt "ok <base64Encoded>"
-        Cipher cipher = null;
+        // Encode parameters to base64
+        String clearTextChallengeEncoded = Base64.getEncoder().encodeToString(clearTextChallenge);
+        String secretKeyEncoded = Base64.getEncoder().encodeToString(secretKeySpec.getEncoded());
+        String ivEncoded = Base64.getEncoder().encodeToString(iv.getIV());
+        // Concatenate command and parameters (challenge, secretKey and IV)
+        String concatenated = "ok" + clearTextChallengeEncoded + secretKeyEncoded + ivEncoded;
+        // Encrypt "<base64Encoded>"
+        Cipher cipher;
+        byte[] cipherTextChallenge;
         try {
             cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
             cipher.init(Cipher.ENCRYPT_MODE, serverPublicKey);
-            cipher.update(("ok " + base64Encoded).getBytes(StandardCharsets.UTF_8));
-            byte[] cipherTextChallenge = cipher.doFinal();
-            return (new String(cipherTextChallenge, StandardCharsets.UTF_8));
+            cipher.update((concatenated).getBytes(StandardCharsets.UTF_8));
+            cipherTextChallenge = cipher.doFinal();
         } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e) {
             logger.severe("This should not be happening!");
             e.printStackTrace();
             shutdown();
+            return null;
         }
-        return null;
+        // Return base64 encoded cipherMessage
+        return (Base64.getEncoder().encodeToString(cipherTextChallenge));
     }
 
     @Override