Best Practices for Roles vs. Claims in ASP.NET Identity

Question

I am completely new to the use of claims in ASP.NETIdentity and want to get an idea of best practices in the use of Roles and/or Claims

Answer 1

Having used various authentication and authorisation techniques over decades, my current MVC application uses the following methodology.

Claims are used for all authorisation. Users are assigned one role (multiple roles are possible but I do not need this) - more below.

As is common practice, A ClaimsAuthorize attribute class is used. Since most controller actions are CRUD, I have a routine in the code-first database generation that iterates all controller actions and creates claim types for each controller action attribute of Read/Edit/Create/Delete. E.g. from,

[ClaimsAuthorize("SomeController", "Edit")]
[HttpPost]

For use at in an MVC View, a base controller class presents view bag items

        protected override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            // get user claims
            var user = filterContext.HttpContext.User as System.Security.Claims.ClaimsPrincipal;

            if (user != null)
            {
                // Get all user claims on this controller. In this controler base class, [this] still gets the descendant instance type, hence name
                List claims = user.Claims.Where(c => c.Type == this.GetType().Name).ToList();

                // set Viewbag with default authorisations on this controller
                ViewBag.ClaimRead = claims.Any(c => c.Value == "Read");
                ViewBag.ClaimEdit = claims.Any(c => c.Value == "Edit");
                ViewBag.ClaimCreate = claims.Any(c => c.Value == "Create");
                ViewBag.ClaimDelete = claims.Any(c => c.Value == "Delete");
            }

            base.OnActionExecuting(filterContext);
        }

For website menus and other non-controller actions, I have other claims. E.g. whether a user can view a particular monetary field.

bool UserHasSpecificClaim(string claimType, string claimValue)
{
    // get user claims
    var user = this.HttpContext.User as System.Security.Claims.ClaimsPrincipal;

    if (user != null)
    {
        // Get the specific claim if any
        return user.Claims.Any(c => c.Type == claimType && c.Value == claimValue);
    }

    return false;
}

public bool UserHasTradePricesReadClaim
{
    get
    {
        return UserHasSpecificClaim("TradePrices", "Read");
    }
}

So where do Roles fit in?

I have a table that links a Role to a (default) set of claims. When setting user authorisation, the default is to give the user the claims of their role. Each user can have more or less claims than the default. To make editing simple, the claims list is show by controller and actions (in a row), with other claims then listed. Buttons are used with a bit of Javascript to select a set of actions to minimise the "clicking" required to select claims. On Save, the users claims are deleted and all of the selected claims are added. The web application loads claims only once, so any changes must prompt a reload within this static data.

Managers can therefore select which claims are in each role and which claims a user has after setting them to a role and those default claims. The system has only a small number of users so managing this data is straightforward