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How to simulate token expiration if an user is idle on an AngulaJS using Bearer Token (OWIN and Katana)

In one of the project where I was involved I used token based authentication to secure a REST API endpoint -  bearer token. The setup was pretty simple, using OWIN and Katana on backend and AngularJS on the client side.
There is a great sample on GitHub, that can be used for learning purposes - https://github.com/tjoudeh/AngularJSAuthentication
This days a new requirement came from the client. The authentication session should expire if there is more than 30 minutes with no activity from client. By default when a token is issued it is available for a specific time interval. The value can be specified as below:
OAuthAuthorizationServerOptions oAuthServerOptions = new OAuthAuthorizationServerOptions
{
AllowInsecureHttp = false,
TokenEndpointPath = new PathString("/token"),
AccessTokenExpireTimeSpan = TimeSpan.FromMinutes(30),
Provider = new SimpleAuthorizationServerProvider(),
AuthenticationMode = AuthenticationMode.Active
};
This will works great in normal scenarios, but in our cases we had some problems.

The token is valid from the moment when is created for a specific time interval, in our case 30 minutes. Even if the user access the services using the token in minute 29, the token will expire and he will need to request a new token or to authenticate again entering his user and password.
An option is to use refresh token and track the last access time in a storage (cache, session or a database). The problems with this solution is:
-          We don’t have a cache yet
-          We don’t use session because we don’t need it
-          A solution with a DB would require an implementation effort and we need to see what is the impact over current DB

Before jumping to the solution that we thought, you should know that on the server there are no information that are stored related to token or user. The token is encrypted using machine key and can used only by the machine or machines that have the same machine key. The bearer token contains all the information related to user, from user ID to claims (current roles or actions that he can do on the server). Don’t forget that we cannot invalidate a bearer token because the server don’t track or store any kind of information related to it.

Based on the above information we measured how long it takes to generate a new bearer token on the server and the performance impact was minimal – with almost no additional resources.

Our solution:
  • On the ActionExecuted of an action filter generate a new bearer token after each call for authenticated users
  • Send this token to the client application
  • Persist this token on the client application
  • Use the token at the next call

The con of this solution is that we generate a new token at each call.
Below you can find the ActionFilter that generate a new token after each call using the claims from the previous call.
public class InjectNewTokenActionFilter : ActionFilterAttribute
{
    public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
    {
        base.OnActionExecuted(actionExecutedContext);

        ClaimsPrincipal principal = GetCurrentPrincipal(actionExecutedContext.ActionContext);
        if (principal == null)
        {
            return;
        }
        var newToken = CreateAuthTicket(principal);

        string token = Startup.OAuthBearerOptions.AccessTokenFormat.Protect(newToken);
        actionExecutedContext.Response.Content.Headers.Add("NewToken", token);            
    }

    private ClaimsPrincipal GetCurrentPrincipal(HttpActionContext actionContext)
    {
        ClaimsPrincipal principal = actionContext.RequestContext.Principal as ClaimsPrincipal;
        return principal;
    }

    private AuthenticationTicket CreateAuthTicket(ClaimsPrincipal oldPrincipal)
    {
        ClaimsIdentity identity = (ClaimsIdentity)oldPrincipal.Identity;
        AuthenticationProperties props = CreateAuthenticationProperties();
        AuthenticationTicket ticket = new AuthenticationTicket(identity, props);
        return ticket;
    }

    private static AuthenticationProperties CreateAuthenticationProperties()
    {
        AuthenticationProperties props = new AuthenticationProperties(new Dictionary<string, string>
        {
            {
                "client_id", string.Empty
            }
        });
        return props;
    }
}
And the JavaScript code that can be used on client side to update the bearer token for each response. This was done by intercept the http response.
var Services = Services || {};
Services.authInterceptorService = function ($q, $injector, $location) {
    ...
    var response = function(response) {
        //Sample
        IF(heather new token is set)
{
       SET NEW VALUE TO globalObjWhereTokenisStored.token = header(‘NewToken’)
}

        return response;
    }

authInterceptorServiceFactory.response = response;

    return authInterceptorServiceFactory;
};

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