At IU, what is CAS?

Beginning November 2, 2017, CAS logins for all IU students, faculty, staff, retirees, affiliates, and those with Academic (ACNP) status will require Two-Step Login (Duo). On November 30, 2017, this will also include group or departmental accounts. IU Guest accounts do not require Two-Step Login. For more, see About using Two-Step Login (Duo) every time I log into CAS.
At Indiana University, the CAS (Central Authentication Service) login service allows you to access multiple IU computing systems after entering your IU username and password only once on a central authentication server. This is often referred to as single sign-on.

IU students, faculty, and staff authenticate through CAS using their IU usernames and passphrases. Individuals who are not officially affiliated with IU can use their IU Guest account or IU Extranet account credentials to authenticate through CAS for access to a limited number of IU services.

CAS currently supports several IU web applications, including One.IU, Duo two-step login, TimeKeeping, PeopleSoft, HRMS (payroll), and the employee Paid Time Off (PTO) system. In the future, other IU systems will use CAS as well.

You will be automatically redirected to the CAS login screen when you access one of the supported systems, unless you have already authenticated to CAS during your session. You can also reach the CAS login screen directly at

CAS currently supports three types of authentication: Active Directory, Duo, and Guest. CAS clients can be deployed on a combination of platforms including Windows, Linux, and both Apache and IIS. CAS supports a variety of tools and languages.

While CAS authentication will only return a username, you can use that username to query ADS and retrieve more information. See At IU, how can I query ADS using LDAP?


To stay informed or provide feedback about Indiana University's Central Authentication Service (CAS), or to ask questions about developing with IU CAS, use the cas-discuss-l mailing list. To subscribe, send email to

This is document akui in the Knowledge Base.
Last modified on 2017-03-13 11:44:50.

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