Summary:
The Central Authentication Service (CAS) is a single sign-on protocol for the web. Its purpose is to permit a user to access multiple applications while providing their credentials (such as user id and password) only once. It also allows web applications to authenticate users without gaining access to a user's security credentials, such as a password. The name CAS also refers to a software package that implements this protocol.

Web TimeSheet works with SAML authentication (Security Assertion Markup Language), but not CAS.