diff --git a/src/main/java/dslab/client/MessageClient.java b/src/main/java/dslab/client/MessageClient.java
index 8d0533c..620acb7 100644
--- a/src/main/java/dslab/client/MessageClient.java
+++ b/src/main/java/dslab/client/MessageClient.java
@@ -41,6 +41,7 @@ public class MessageClient implements IMessageClient, Runnable {
     private BufferedReader dmapIn;
 
     private Cipher aesCipher;
+    private byte[] challenge;
 
     /**
      * Creates a new client instance.
@@ -160,9 +161,9 @@ public class MessageClient implements IMessageClient, Runnable {
     private byte[] generateChallenge(PublicKey serverPublicKey) {
         SecureRandom secureRandom = new SecureRandom();
         // Generate new random 32 byte challenge
-        byte[] clearTextChallenge = new byte[32];
-        secureRandom.nextBytes(clearTextChallenge);
-        return clearTextChallenge;
+        this.challenge = new byte[32];
+        secureRandom.nextBytes(this.challenge);
+        return this.challenge;
     }
 
     private String generateChallengeMessage(PublicKey serverPublicKey) {