Registration

- Trusted information (e.g. certified information, security code, information which is matched to certifiable document).

- Necessity of physical card or account.

- Implementation of additional security techniques (e.g. CAPTCHA, secret question).

Authentication (login)

- Data which increases difficulty to log into the account. (e.g. mobile number, physical card number, system generated ID).

Back-up authentication

- Trusted information.

(password recovery)

- Physical card or account number.