var provider = new CookieAuthenticationProvider();
provider.OnApplyRedirect = ctx =>
{
    if (ctx.Request.Query["s"] != null)
    {
        var ticket = LoadTicket(ctx.Request.Query["s"]);
        var uri = RemoveQueryStringByKey(ctx.Request.Uri.ToString(), "s");
        ticket.Properties.IsPersistent = true;
        ctx.OwinContext.Authentication.SignIn(ticket.Properties, ticket.Identity);
        ctx.Response.Redirect(uri);
        return;
    }
}

public class SingleSignOnAuthenticationHandler : AuthenticationHandler<AuthenticationOptions>
{
    protected override Task<AuthenticationTicket> AuthenticateCoreAsync()
    {

        var sessionIdentifier = Request.Query["s"];
        if (sessionIdentifier == null)
            return Task.FromResult<AuthenticationTicket>(null);

        var ticket = LoadTicket(sessionIdentifier);
        if (ticket == null)
            return Task.FromResult<AuthenticationTicket>(null);

        Context.Authentication.SignIn(ticket.Properties, ticket.Identity);
        return Task.FromResult(new AuthenticationTicket(ticket.Identity, ticket.Properties));
    }
}

app.UseCookieAuthentication(new CookieAuthenticationOptions
{
    AuthenticationType = "ApplicationCookie", // <--- THIS STRING
    LoginPath = new PathString(VirtualPathUtility.ToAbsolute("~/Account/Login")),
    Provider = provider
});

public class SingleSignOnAuthenticationHandler : AuthenticationHandler<AuthenticationOptions>
{
    protected override Task<AuthenticationTicket> AuthenticateCoreAsync()
    {

        var sessionIdentifier = Request.Query["s"];
        if (sessionIdentifier == null)
            return Task.FromResult<AuthenticationTicket>(null);

        var ticket = LoadTicket(sessionIdentifier);
        if (ticket == null)
            return Task.FromResult<AuthenticationTicket>(null);

        ticket.Properties.IsPersistent = true;

        // ** LOOK HERE **
        //new identity, but with the correct authentication type
        var identity = new ClaimsIdentity(ticket.Identity.Claims, "ApplicationCookie", ClaimTypes.Name, ClaimTypes.Role);
        Context.Authentication.SignIn(ticket.Properties, identity);
        return Task.FromResult(new AuthenticationTicket(identity, ticket.Properties));
    }
}