public void testBase64StringOperations() throws Exception {
        char[] plaintext = "TestPassword456".toCharArray();

        // Encrypt to string
        String encryptedStr = storage.encryptToString(plaintext);
        assertNotNull(encryptedStr, "Encrypted string should not be null");
        assertFalse(encryptedStr.contains("TestPassword456"), "Plaintext should not be visible in encrypted string");

        // Should be valid base64