(a) illustrates the concept of security and safety can be seen as an “appropriate state” during the ongoing detection, an “appropriate process” (sequence of states) in the ex-post evaluation, and an “appropriate situation” (trend in the development of states) in the ex-ante awareness. The essence of studying security lies in examining whether the changing states are secure and the factors inside and outside the state changes are referred to as behavior. (b) describes the conceptual framework of behavioral authentication