Recently by the privacy & data security law, when a user registers the online membership, we need to take action to check a progress of identification without resident registration number. On the most of websites, I-PIN is used by identification instead of the resident registration number. However, I-PIN causes dangerous situations if someone steals the ID and a password, the personal data can be easy to exposure. In this paper, we propose the OTP, which can solve all these problems by guaranteeing the identification of unlinkability. This type of method would help the process of membership registration without fixed data like ID and a password in online so it would be very useful to security of private data.