diff --git a/src/main/java/dslab/client/MessageClient.java b/src/main/java/dslab/client/MessageClient.java
index 233baf6..0595dad 100644
--- a/src/main/java/dslab/client/MessageClient.java
+++ b/src/main/java/dslab/client/MessageClient.java
@@ -14,10 +14,8 @@ import java.util.logging.Logger;
 import dslab.ComponentFactory;
 import dslab.util.Config;
 
-import javax.crypto.BadPaddingException;
-import javax.crypto.Cipher;
-import javax.crypto.IllegalBlockSizeException;
-import javax.crypto.NoSuchPaddingException;
+import javax.crypto.*;
+import javax.crypto.spec.IvParameterSpec;
 
 public class MessageClient implements IMessageClient, Runnable {
     private static final Logger logger = Logger.getLogger(MessageClient.class.getName());
@@ -118,7 +116,20 @@ public class MessageClient implements IMessageClient, Runnable {
         }
     }
 
-    public String generateChallenge(PublicKey serverPublicKey) {
+    private SecretKey generateSecretKey() throws NoSuchAlgorithmException {
+        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
+        keyGenerator.init(256);
+        return keyGenerator.generateKey();
+    }
+
+    private byte[] generateIv() {
+        // Size of IV corresponds to AES block size (=128bits=16bytes)
+        byte[] iv = new byte[16];
+        new SecureRandom().nextBytes(iv);
+        return new IvParameterSpec(iv).getIV();
+    }
+
+    private String generateChallenge(PublicKey serverPublicKey) {
         SecureRandom secureRandom = new SecureRandom();
         try {
             Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");