CAS

The Central Authentication Service (CAS) is a single-sign-on/single-sign-off protocol for the web. It permits a user to access multiple applications while providing their credentials (such as userid and password) only once to a central CAS Server application.

– CAS Protocol Specification

CAS is an open source, platform-independent, central single sign-on (SSO) service supporting a variety of well-known protocols. Spring Security has first-class support for CAS, and the implementation is quite simple for an enterprise having a central CAS server. CAS is based on Spring Framework, and the architecture is quite simple, as shown in the following diagram:

Figure 1: CAS architecture (figure adapted from https://apereo.github.io)

The CAS server is a Java servlet-based application built on Spring Framework (Spring MVC and Spring Web Flow). It authenticates and grants...