diff --git a/src/keys/CompositeKey.cpp b/src/keys/CompositeKey.cpp
index 16b48592e..2270d96eb 100644
--- a/src/keys/CompositeKey.cpp
+++ b/src/keys/CompositeKey.cpp
@@ -17,6 +17,7 @@
 
 #include "CompositeKey.h"
 #include "CompositeKey_p.h"
+#include "ChallengeResponseKey.h"
 
 #include <QtConcurrent>
 #include <QElapsedTimer>
@@ -47,7 +48,7 @@ void CompositeKey::clear()
 
 bool CompositeKey::isEmpty() const
 {
-    return m_keys.isEmpty();
+    return m_keys.isEmpty() && m_challengeResponseKeys.isEmpty();
 }
 
 CompositeKey* CompositeKey::clone() const
@@ -67,6 +68,9 @@ CompositeKey& CompositeKey::operator=(const CompositeKey& key)
     for (const Key* subKey : asConst(key.m_keys)) {
         addKey(*subKey);
     }
+    Q_FOREACH (const ChallengeResponseKey* subKey, key.m_challengeResponseKeys) {
+        addChallengeResponseKey(*subKey);
+    }
 
     return *this;
 }
@@ -142,11 +146,35 @@ QByteArray CompositeKey::transformKeyRaw(const QByteArray& key, const QByteArray
     return result;
 }
 
+QByteArray CompositeKey::challenge(const QByteArray& seed) const
+{
+    /* If no challenge response was requested, return nothing to
+     * maintain backwards compatability with regular databases.
+     */
+    if (m_challengeResponseKeys.length() == 0) {
+        return QByteArray();
+    }
+
+    CryptoHash cryptoHash(CryptoHash::Sha256);
+
+    Q_FOREACH (ChallengeResponseKey* key, m_challengeResponseKeys) {
+        key->challenge(seed);
+        cryptoHash.addData(key->rawKey());
+    }
+
+    return cryptoHash.result();
+}
+
 void CompositeKey::addKey(const Key& key)
 {
     m_keys.append(key.clone());
 }
 
+void CompositeKey::addChallengeResponseKey(const ChallengeResponseKey& key)
+{
+    m_challengeResponseKeys.append(key.clone());
+}
+
 int CompositeKey::transformKeyBenchmark(int msec)
 {
     TransformKeyBenchmarkThread thread1(msec);
diff --git a/src/keys/CompositeKey.h b/src/keys/CompositeKey.h
index 3290d3671..66ad91ad9 100644
--- a/src/keys/CompositeKey.h
+++ b/src/keys/CompositeKey.h
@@ -21,6 +21,7 @@
 #include <QList>
 
 #include "keys/Key.h"
+#include "keys/ChallengeResponseKey.h"
 
 class CompositeKey : public Key
 {
@@ -36,7 +37,10 @@ public:
     QByteArray rawKey() const;
     QByteArray transform(const QByteArray& seed, quint64 rounds,
                          bool* ok, QString* errorString) const;
+    QByteArray challenge(const QByteArray& seed) const;
+
     void addKey(const Key& key);
+    void addChallengeResponseKey(const ChallengeResponseKey& key);
 
     static int transformKeyBenchmark(int msec);
 
@@ -45,6 +49,7 @@ private:
                                       quint64 rounds, bool* ok, QString* errorString);
 
     QList<Key*> m_keys;
+    QList<ChallengeResponseKey*> m_challengeResponseKeys;
 };
 
 #endif // KEEPASSX_COMPOSITEKEY_H