> For the complete documentation index, see [llms.txt](https://docs.ngsurvey.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ngsurvey.com/form-management/security/security-items/cas-authentication.md). # CAS Authentication ## 🔐 What is CAS authentication ? Using the [central authentication service](https://en.wikipedia.org/wiki/Central_Authentication_Service) (CAS) you can enable single-sign-on on your ngSurvey forms using a CAS server to authenticate the respondents. The CAS security item will automatically redirect the respondent to the CAS server if it can't find any ticket. If a ticket was found but the ticket was invalid it will ask the respondent to log back into the CAS server. ## 🔅 CAS properties * **`CAS URL`**URL of the server hosting your CAS. eg: * **`Allow multiple submissions`** can a respondent take part multiple time to the same survey. * **`Login message`** is the message that will be shown to the respondent on the login page that will allow him load the CAS server login page. This message will be shown if ngSurvey fails to authenticate automatically the user. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.ngsurvey.com/form-management/security/security-items/cas-authentication.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.