assertNotNull(decrypted, "Decrypted empty data should not be null");
        assertEquals(0, decrypted.length, "Decrypted empty array should have zero length");
    }

    @Test
    public void testEncryptDecryptNull() throws Exception {
        byte[] encrypted = storage.encryptCredentials(null);
        assertNull(encrypted, "Encrypting null should return null");

        char[] decrypted = storage.decryptCredentials(null);