In this paper, we propose combined password authentication scheme resistant to shoulder surfing attack.
Proposed scheme improves the vulnerable part of text-based password authentication scheme about shoulder
surfing. Our scheme combined existing text-based authentication factors with user behavior information as
the part of the user authentication. Thus, our scheme consider the user efficiency. Because none of other
devices is required as a secondary authentication method that is required in two-channel authentication
scheme. In addition, our scheme offer the same level of user confirmation factor, as in two-channel
authentication scheme. Furthermore, even if text-based password is exposed by shoulder surfing attack,
another authentication factor-user behavior pattern- is not vulnerable to this attack. User behavior pattern is
biometric data that reflects users own behavior. Thus, that is hard to copy as same as the original.
Therefore, our scheme is shoulder surfing resistant