I am implementing 2FA for users in Umbraco 8 backoffice and I have the most of it working. But I got stuck at a point where I need user data but I cannot figure out how to get it.

I need to know which user is logging in after he/she/it has entered the credentials and lands on the 2FA custom login page but before submitting a code on that page.

The additional login 2FA page is shown via

public string GetTwoFactorView(IOwinContext owinContext, UmbracoContext umbracoContext, string username) =>
        PackageConstants.PathToMfaHtmlTemplate;

This template has an angularjs controller:

<div ng-controller="mfaLoginController" class="umb-login-container">
  //...
</div>

and in the controller I got access to the services:

userService
authResource

Unfortunately, both services doesn't seem to have the user data yet I need. It seems the user data is available after calling executing the verify2FACode:

        authResource.verify2FACode(providerName, quoted($scope.code)).then(
            data => {
                userService.setAuthenticationSuccessful(data);

                //Normally, this should be $scope.submit(true); 
                //But this isn't working in umbraco 8, probably a bug?.
                //For more info, check https://github.com/Dallas-msc/umbraco-2fa-with-google-authenticator/issues/1
                $scope.$parent.vm.onLogin();
            },
            () => $scope.pinCodeMessage = pinCodInvalidMessage
        );

The data in setAuthenticationSuccessful(data) seems to have the user info so this info is too late.

Is there another service I could inject that actually got the information I need?

Also, I need this information for some API calls I want to make. I figured out that a cookie is set after the login step 1, named

.AspNet.UmbracoTwoFactorCookie

And I can read the content of the cookie of course with

var mfaCookie = Request.Headers.GetCookies(".AspNet.UmbracoTwoFactorCookie").FirstOrDefault()
                .Cookies.FirstOrDefault(cookie => cookie.Name == ".AspNet.UmbracoTwoFactorCookie").Value;

But this contains an encrypted OWIN string and I haven't succeeded yet in decrypting the string. Many decryptors I found uses the MachineKey decrypting but when I try to use those, it always ends up in the error:

Error occurred during a cryptographic operation.

Even when I put a machinekey in my web.config, I still get this error.

Is there a way to get the user data (even when login is not successful yet because the user needs to enter a PIN-code) in the backend instead of retrieving it in the frontend perhaps?

PS: I also opened a topic on stackoverflow as I am that eager to solve this issue.