diff --git a/src/keys/CompositeKey.cpp b/src/keys/CompositeKey.cpp
index c5c50e110..fc72dd6a9 100644
--- a/src/keys/CompositeKey.cpp
+++ b/src/keys/CompositeKey.cpp
@@ -22,6 +22,15 @@
 
 #include <QtCore/QtConcurrentRun>
 
+CompositeKey::CompositeKey()
+{
+}
+
+CompositeKey::CompositeKey(const CompositeKey& key)
+{
+    *this = key;
+}
+
 CompositeKey::~CompositeKey()
 {
     qDeleteAll(m_keys);
@@ -32,6 +41,14 @@ CompositeKey* CompositeKey::clone() const
     return new CompositeKey(*this);
 }
 
+CompositeKey& CompositeKey::operator=(const CompositeKey& key)
+{
+    Q_FOREACH (Key* subKey, key.m_keys) {
+        m_keys.append(subKey->clone());
+    }
+
+    return *this;
+}
 
 QByteArray CompositeKey::rawKey() const
 {
@@ -46,6 +63,9 @@ QByteArray CompositeKey::rawKey() const
 
 QByteArray CompositeKey::transform(const QByteArray& seed, int rounds) const
 {
+    Q_ASSERT(seed.size() == 32);
+    Q_ASSERT(rounds > 0);
+
     QByteArray key = rawKey();
 
     QFuture<QByteArray> future1 = QtConcurrent::run(transformKeyRaw, key.left(16), seed, rounds);
diff --git a/src/keys/CompositeKey.h b/src/keys/CompositeKey.h
index 4a1d0172c..017ffbfdd 100644
--- a/src/keys/CompositeKey.h
+++ b/src/keys/CompositeKey.h
@@ -25,8 +25,11 @@
 class CompositeKey : public Key
 {
 public:
+    CompositeKey();
+    CompositeKey(const CompositeKey& key);
     ~CompositeKey();
     CompositeKey* clone() const;
+    CompositeKey& operator=(const CompositeKey& key);
 
     QByteArray rawKey() const;
     QByteArray transform(const QByteArray& seed, int rounds) const;
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index e4cfeb03d..c878c9715 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -103,6 +103,8 @@ add_unit_test(NAME testgroup SOURCES TestGroup.cpp MOCS TestGroup.h LIBS ${TEST_
 
 add_unit_test(NAME testkeepass2xmlreader SOURCES TestKeePass2XmlReader.cpp MOCS TestKeePass2XmlReader.h LIBS ${TEST_LIBRARIES})
 
+add_unit_test(NAME testkeys SOURCES TestKeys.cpp MOCS TestKeys.h LIBS ${TEST_LIBRARIES})
+
 add_unit_test(NAME testkeepass2reader SOURCES TestKeePass2Reader.cpp MOCS TestKeePass2Reader.h LIBS ${TEST_LIBRARIES})
 
 add_unit_test(NAME testkeepass2writer SOURCES TestKeePass2Writer.cpp MOCS TestKeePass2Writer.h LIBS ${TEST_LIBRARIES})
diff --git a/tests/TestKeys.cpp b/tests/TestKeys.cpp
new file mode 100644
index 000000000..0698f8701
--- /dev/null
+++ b/tests/TestKeys.cpp
@@ -0,0 +1,53 @@
+/*
+ *  Copyright (C) 2011 Felix Geyer <debfx@fobos.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "TestKeys.h"
+
+#include <QtTest/QTest>
+
+#include "crypto/Crypto.h"
+#include "keys/CompositeKey.h"
+#include "keys/PasswordKey.h"
+
+void TestKeys::initTestCase()
+{
+    Crypto::init();
+}
+
+void TestKeys::testComposite()
+{
+    CompositeKey* compositeKey1 = new CompositeKey();
+    PasswordKey* passwordKey1 = new PasswordKey();
+    PasswordKey* passwordKey2 = new PasswordKey("test");
+
+    compositeKey1->addKey(*passwordKey1);
+    compositeKey1->addKey(*passwordKey2);
+    delete passwordKey1;
+    delete passwordKey2;
+
+    QVERIFY(compositeKey1->transform(QByteArray(32, '\0'), 1).size() == 32);
+
+    // make sure the subkeys are copied
+    CompositeKey* compositeKey2 = compositeKey1->clone();
+    delete compositeKey1;
+
+    QVERIFY(compositeKey2->transform(QByteArray(32, '\0'), 1).size() == 32);
+
+    delete compositeKey2;
+}
+
+QTEST_MAIN(TestKeys);
diff --git a/tests/TestKeys.h b/tests/TestKeys.h
new file mode 100644
index 000000000..d525c706a
--- /dev/null
+++ b/tests/TestKeys.h
@@ -0,0 +1,32 @@
+/*
+ *  Copyright (C) 2011 Felix Geyer <debfx@fobos.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSX_TESTKEYS_H
+#define KEEPASSX_TESTKEYS_H
+
+#include <QtCore/QObject>
+
+class TestKeys : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void initTestCase();
+    void testComposite();
+};
+
+#endif // KEEPASSX_TESTKEYS_H