@Test
    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");

     *
     * @param plaintext the credentials to encrypt
     * @return base64 encoded encrypted credentials
     * @throws GeneralSecurityException if encryption fails
     */
    public String encryptToString(char[] plaintext) throws GeneralSecurityException {
        byte[] encrypted = encryptCredentials(plaintext);
        return Base64.getEncoder().encodeToString(encrypted);
    }

    /**