Cryptanalysis of Security Analysis and Enhancements of a Remote User Authentication Scheme

The main purpose of user authentication schemes is to verify the authorized user using a server via an insecure channel. With the authentication, a server and a user could have a mutual authentication. In 2019, Cao proposed an improvement of a user authentication scheme. The scheme was postulated in that it could protect from the several possible attacks and have the following advantages: Identity preservation, not only to resist the slow wrong password detection, to resist the user masquerading, the password guessing, and the sever masquerading attacks, but also to have a mutual authentication between servers and users. However, we will show his scheme is not with the capacity to against the denial of service and on-line password guessing attacks in this article. In order to improve that authentication scheme, this work proposes an enhanced remote authentication scheme with the capacity to resist those vulnerabilities as shown in Cao-Sun-Cao's scheme.