public synchronized boolean login(RSACipher rsa, int length, byte[] pass) {
        if (LoggedIn) {
            Logger.info("<" + Name + ">łɃOCĂ܂B");
            return false;
        }
        if (Password.length != length) {
            Logger.info("<" + Name + ">Login failed.[Password error.]");
            return false;
        }
        byte[] enc_password = null;
        try {
            enc_password = rsa.encData(Password, 0, Password.length);
        } catch (IOException ex) {
            ex.printStackTrace();
            Logger.error("Error while encrypting data.@User#login");
            return false;
        }
        if (enc_password.length != pass.length) {
            Logger.info("<" + Name + ">Login failed.[Password error.2]");
            return false;
        }
        for (int i = 0; i < enc_password.length; i++) {
            if (enc_password[i] != pass[i]) {
                return false;
            }
        }
        Cipher = rsa;
        LoggedIn = true;
        Initialized = false;
        return true;
    }