ABSTRACT
This chapter reviews the user authentication methods from the perspectives of usability, security, and their potential conflict. Despite the well-known security and usability issues, passwords are still the most popular method of end-user authentication. To counter this situation, more and more complex CAPTCHAs are developed to protect the systems, thus creating additional usability issues. A security flaw of GlanceID, just as with biometrics in general, is that if someone succeeds in forgery or replay, there is no way to disable the credential and issue a new one. The primary grounds for comparison have to do with the most representative authentication methods currently in the market and also a novel advanced user authentication method created by the authors which has been commercialized. The usability of user authentication mechanisms has seldom been investigated, and since security mechanisms are conceived, implemented, put into practice, and violated by people, human factors should be taken into account in the design.
