/**
     * Decrypt credentials from a base64 string
     *
     * @param encryptedString base64 encoded encrypted credentials
     * @return decrypted credentials
     * @throws GeneralSecurityException if decryption fails
     */
    public char[] decryptFromString(String encryptedString) throws GeneralSecurityException {
        if (encryptedString == null) {
            return null;
        }