ServiceStack WIF cookie auth provider

WifCookieAuthProvider.cs

using System.Linq;
using System.Threading;
using Microsoft.IdentityModel.Claims;
using ServiceStack.Common.Web;
using ServiceStack.Configuration;
using ServiceStack.ServiceInterface;
using ServiceStack.ServiceInterface.Auth;

namespace YourApp
{
    public class WifCookieAuthProvider : AuthProvider
    {
        public static string Name = "wifcookie";
        public static string Realm = "/auth/wifcookie";

        public WifCookieAuthProvider(IResourceManager appSettings)
            : base(appSettings, Realm, Name) { }

        public override object Authenticate(IServiceBase authService, IAuthSession session, Auth request)
        {
            var identity = Thread.CurrentPrincipal.Identity as IClaimsIdentity;
            if (identity != null && identity.IsAuthenticated)
            {
                session.Email = GetClaim(identity, ClaimTypes.Email);
                session.FirstName = GetClaim(identity, ClaimTypes.GivenName);
                session.LastName = GetClaim(identity, ClaimTypes.Surname);
                session.UserName = GetClaim(identity, ClaimTypes.Name, ClaimTypes.NameIdentifier);
                session.UserAuthId = GetClaim(identity, ClaimTypes.NameIdentifier, ClaimTypes.Name);
                session.UserAuthName = GetClaim(identity, ClaimTypes.Name, ClaimTypes.NameIdentifier);
                session.IsAuthenticated = true;

                authService.SaveSession(session);
                return new AuthResponse
                {
                    UserName = session.UserName,
                    SessionId = session.Id
                };
            }

            throw HttpError.Unauthorized("User is not authenticated");
        }

        public override bool IsAuthorized(IAuthSession session, IOAuthTokens tokens, Auth request = null)
        {
            bool authorized = !string.IsNullOrEmpty(session.UserAuthName);
            return authorized;
        }

        public static string GetClaim(IClaimsIdentity identity, params string[] claimTypes)
        {
            foreach (var claimType in claimTypes)
            {
                var claim = identity.Claims.SingleOrDefault(c => c.ClaimType == claimType);
                if (claim != null)
                    return claim.Value;

            }
            return null;
        }
    }
}