[keycloak-dev] Improve back-button and refreshes in authenticators?

Stian Thorgersen sthorger at redhat.com
Fri Mar 17 03:45:52 EDT 2017

I repeat:

Before we discuss implementation though, let's figure out what the ideal
user experience would be then figure out how to implement it. What about:

* Refresh just works
* Back button will display a nicer page, something like "Page has expired.
To restart the login process click here. To continue the login process
click here.". Or Back button could just go to the start of the flow always.
* Resubmitting forms will just display the page above
* No need to do redirects. Redirects is bad for performance, but also has
twice the response time which is not good from a usability perspective

Is this the optimal user experience? Or should we do something else?

On 17 March 2017 at 08:44, Stian Thorgersen <sthorger at redhat.com> wrote:

> Can we please get back to discussing what the best user experience is
> first. Then we can discuss implementations?
> On 16 March 2017 at 18:37, Bill Burke <bburke at redhat.com> wrote:
>> On 3/16/17 10:50 AM, Marek Posolda wrote:
>> On 16/03/17 15:27, Bill Burke wrote:
>> * Hidden field in a form is not a good approach.  Its very brittle and
>> will not work in every situation.  So huge -1 there.
>> * browser back button is not required to resubmit the HTTP request as the
>> page can be rendered from cache.  Therefore you couldn't have a "Page
>> Expired" page displayed when the back button is pressed without setting the
>> header "Cache-Control: no-store, must-revalidate, max-age=0"
>> Maybe we can do some javascript stuff like this:
>> http://stackoverflow.com/questions/9046184/reload-the-site-
>> when-reached-via-browsers-back-button
>> But that would mean that we will need to inject some common javascript
>> stuff into every HTML form displayed by authentication SPI. Could we rely
>> on that?
>> I don't think this is a good approach as Authenticator develoeprs would
>> have to do the same thing.
>> * Furthermore, without some type of code/information within the URL, you
>> also wouldn't know if somebody clicked the back button or not or whether
>> this was a page refresh or some other GET request.
>> Once we have the cookie with loginSessionID, we can lookup the
>> loginSession. And loginSession will contain last code (same like
>> clientSession now) and last authenticator. Then we just need to compare the
>> code from the loginSession with the code from request. If it matches, we
>> are good. If it doesn't match, it's likely the refresh of some previous
>> page and in that case, we can just redirect to last authenticator.
>> This is the current behavior, but instead of using a cookie, the "code"
>> is stored in the URL.
>> With only a cookie though and no URL information, you won't know the
>> different between a Back Button and a Page Refresh for GET requests.  For
>> POST requests, you won't be able to tell the differencee between a Back
>> Button, Page Refresh, or whether the POST is targeted to an actual
>> Authenticator.
>> The more I think about it, things should probably stay the way it
>> currently is, with improvements on user experience.  I think we can support
>> what Stian suggested with the current implementation.
>> Not sure if we also need to track all codes, so we are able to distinct
>> between the "expired" code, and between the "false" code, which was never
>> valid and was possibly used by some attacker for CSRF. Maybe we can sign
>> codes with HMAC, so we can verify if it is "expired" or "false" code
>> without need to track the list of last codes.
>> This has been done in the past.  Then it was switched to using the same
>> code throughout the whole flow, then Stian switched it to changing the code
>> throughout the flow.  I don't know if he uses a hash or not.
>> Bill

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