Then, we analyze the most popular pattern-lock method in terms of security and usability. Finally, we
propose three-factor based authentication method which can improve security level of conventional
one-factor based pattern-lock method. The proposed method includes three-factors which are knowledge,
possession, and biometrics. In other words, it includes pattern shape, fingerprint, and pressure variation as
the authentication factors during the owner draw the pattern. The proposed method has trippled the
authentication factor compared to the conventional pattern-lock method. However, if the smartphone screen
has a built-in pressure and fingerprint sensor, the fingerprint and pressure factors can be verified
simultaneously during the pattern is drawn. Therefore, the time required for authentication is similar to that
of conventional method, and the security level is much higher. As a result of performance comparison, the
proposed method is robust against social engineering and provides similar level of usability compared to the
conventional pattern-lock method.