keys: CompositeKey: Add ChallengeResponseKey support

* Each Challenge Response Key consists of a list of regular keys and now
  challenge response keys.
* Copy ChallengeResponseKeys when copying the object.
* Challenge consists of challenging each driver in the list and hashing
  the concatenated data result using SHA256.

Signed-off-by: Kyle Manna <kyle@kylemanna.com>

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