Recently I have found an excellent question on Stackoverflow. The OP asks why does claim added to Idenetity after calling AuthenticationManager.SignIn still persist to the cookie.

The sample code was like this:

ClaimsIdentity identity = UserManager.CreateIdentity(user, DefaultAuthenticationTypes.ApplicationCookie );

var claim1 = new Claim(ClaimTypes.Country, "Arctica");

AuthenticationManager.SignIn(new AuthenticationProperties { IsPersistent = true }, identity );

var claim2 = new Claim(ClaimTypes.Country, "Antartica");

Yeah, why does claim2 is available after cookie is already set.

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When I’d like to find out about technologies used on the site, I look on HTTP header, then on cookies. Usually combination of these can give me a pretty detailed information about underlying technology used. Cookie names are very bad for that – search for any cookie name and you’ll get a lot of information about the technology.

To hide yourself, you can rename cookies from standard to something random. In Asp.Net Identity you can do that via CookieName property on CookieAuthenticationOptions class in configuration:

app.UseCookieAuthentication(new CookieAuthenticationOptions
    AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
    LoginPath = new PathString("/Account/Login"),
    Provider = new CookieAuthenticationProvider
        OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<UserManager, ApplicationUser>(
            validateInterval: TimeSpan.FromMinutes(0),
            regenerateIdentity: (manager, user) => manager.GenerateUserIdentityAsync(user))
    CookieName = "jumpingjacks",

See the jumpingjacks string? that will be the cookie name when users login. You can find the full project source code in my Github repository

UPD: Here is another good solution to this problem if you are running your own IIS.

Last week I was updating one of applications I work on to ASP.NET Identity. For a specific reasons I could not deploy to Azure for a while. But I did run all the tests locally and everything worked just fine.

When I mostly finished with Identity conversion, I finally managed to deploy the application to Azure Web-Sites. And it worked fine.. until I tried registering a user.

At that point I had an exception exploding in my face:

System.Security.Cryptography.CryptographicException: The data protection operation was unsuccessful. This may have been caused by not having the user profile loaded for the current thread's user context, which may be the case when the thread is impersonating.

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