assertArrayEquals(plaintext, decrypted);
        assertNotEquals(new String(plaintext), new String(encrypted));
    }

    @Test
    @DisplayName("Should perform DES encryption/decryption")
    void testDES() throws Exception {
        // Given
        byte[] key = "testkey1".getBytes(); // 8 bytes for DES
        byte[] plaintext = "12345678".getBytes(); // 8 bytes (DES block size)

        // When