Cookieless Forms Authentication

ASP.NET 2.0 supports cookieless forms authentication. This feature is controlled by the cookieless attribute of the forms element. This attribute can be set to one of the following four values:

* UseCookies. This value forces the FormsAuthenticationModule class to use cookies for transmitting the authentication ticket.
* UseUri. This value directs the FormsAuthenticationModule class to rewrite the URL for transmitting the authentication ticket.
* UseDeviceProfile. This value directs the FormsAuthenticationModule class to look at the browser capabilities. If the browser supports cookies, then cookies are used; otherwise, the URL is rewritten.
* AutoDetect. This value directs the FormsAuthenticationModule class to detect whether the browser supports cookies through a dynamic detection mechanism. If the detection logic indicates that cookies are not supported, then the URL is rewritten.

If your application is configured to use cookieless forms authentication and the FormsAuthentication.RedirectFromLoginPage method is being used, then the FormsAuthenticationModule class automatically sets the forms authentication ticket in the URL. The following code example shows what a typical URL looks like after it has been rewritten:

http://localhost/CookielessFormsAuthTest/(F(-k9DcsrIY4CAW81Rbju8KRnJ5o_gOQe0I1E_jNJLYm74izyOJK8GWdfoebgePJTEws0Pci7fHgTOUFTJe9jvgA2))/Test.aspx


The section of the URL that is in parentheses contains the data that the cookie would usually contain. This data is removed by ASP.NET during request processing. This step is performed by the ASP.NET ISAPI filter and not in an HttpModule class. If you read the Request.Path property from an .aspx page, you won't see any of the extra information in the URL. If you redirect the request, the URL will be rewritten automatically.

Note It is not possible to secure authentication tickets contained in URLs. When security is paramount, you should use cookies to store authentication tickets.

http://msdn.microsoft.com/en-us/library/ff647070.aspx