How to retrieve ClaimsPrincipal from JWT in asp.net core

Question

In my solution, I have two projects. 1) Web API and 2) MVC. I am using ASP.NET Core. API issues JWT token and MVC consumes it to get protected resources. I am using openiddict library to issue JWT. In MVC project, in AccountController Login method, I want to retrieve ClaimsPrincipal (using JwtSecurityTokenHandler ValidateToken method) and assign to HttpContext.User.Claims and HttpContext.User.Identity. I want to store the token in session and for each request after successful login, pass it in header to Web API. I can successfully, issue JWT and consume it in MVC project, but when I try to retrieve ClaimsPrincipal it throws me an error. First of all, I am not even sure whether this retrieving of ClaimsPrinciapal from JWT is a right approach or not. And if it is, what is the way forward.

WebAPI.Startup.CS

public class Startup
{
    public static string SecretKey => "MySecretKey";
    public static SymmetricSecurityKey SigningKey => new SymmetricSecurityKey(Encoding.ASCII.GetBytes(SecretKey));

    public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddEnvironmentVariables();
        Configuration = builder.Build();
    }

    public IContainer ApplicationContainer { get; private set; }

    public IConfigurationRoot Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public IServiceProvider ConfigureServices(IServiceCollection services)
    {
        // Add framework services.
        services.AddCors();
        services.AddMvc().AddJsonOptions(options => { options.SerializerSettings.ContractResolver = new Newtonsoft.Json.Serialization.DefaultContractResolver(); });
        services.AddAutoMapper();

        services.AddDbContext<MyDbContext>(options =>
        {
            options.UseMySql(Configuration.GetConnectionString("MyDbContext"));
            options.UseOpenIddict();
        });

        services.AddOpenIddict(options =>
        {
            options.AddEntityFrameworkCoreStores<TelescopeContext>();
            options.AddMvcBinders();
            options.EnableTokenEndpoint("/Authorization/Token");
            options.AllowPasswordFlow();
            options.AllowRefreshTokenFlow();
            options.DisableHttpsRequirement();
            options.UseJsonWebTokens();
            options.AddEphemeralSigningKey();
            options.SetAccessTokenLifetime(TimeSpan.FromMinutes(30));
        });

        var config = new MapperConfiguration(cfg => { cfg.AddProfile(new MappingProfile()); });
        services.AddSingleton(sp => config.CreateMapper());

        // Create the Autofac container builder.
        var builder = new ContainerBuilder();

        // Add any Autofac modules or registrations.
        builder.RegisterModule(new AutofacModule());

        // Populate the services.
        builder.Populate(services);

        // Build the container.
        var container = builder.Build();

        // Create and return the service provider.
        return container.Resolve<IServiceProvider>();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IApplicationLifetime applicationLifetime)
    {
        loggerFactory.AddConsole(Configuration.GetSection("Logging"));
        loggerFactory.AddDebug();

        app.UseCors(builder => builder.WithOrigins("http://localhost:9001/")
                                      .AllowAnyOrigin());

        app.UseJwtBearerAuthentication(new JwtBearerOptions
        {
            Authority = "http://localhost:9001/",
            AutomaticAuthenticate = true,
            AutomaticChallenge = true,
            Audience = "http://localhost:9000/",
            RequireHttpsMetadata = false,
            TokenValidationParameters = new TokenValidationParameters()
            {
                ValidateIssuer = true,
                ValidIssuer = "http://localhost:9001/",

                ValidateAudience = true,
                ValidAudience = "http://localhost:9000",

                ValidateLifetime = true,
                IssuerSigningKey = SigningKey
            }
        });

        app.UseOpenIddict();
        app.UseMvcWithDefaultRoute();
        applicationLifetime.ApplicationStopped.Register(() => this.ApplicationContainer.Dispose());
    }
}

WebAPI.AuthorizationController.cs which issues JWT.

[Route("[controller]")]
public class AuthorizationController : Controller
{
    private IUsersService UserService { get; set; }

    public AuthorizationController(IUsersService userService)
    {
        UserService = userService;
    }

    [HttpPost("Token"), Produces("application/json")]
    public async Task<IActionResult> Exchange(OpenIdConnectRequest request)
    {
        if (request.IsPasswordGrantType())
        {
            if (await UserService.AuthenticateUserAsync(new ViewModels.AuthenticateUserVm() { UserName = request.Username, Password = request.Password }) == false)
                return Forbid(OpenIdConnectServerDefaults.AuthenticationScheme);

            var user = await UserService.FindByNameAsync(request.Username);

            var identity = new ClaimsIdentity(OpenIdConnectServerDefaults.AuthenticationScheme, OpenIdConnectConstants.Claims.Name, null);
            identity.AddClaim(OpenIdConnectConstants.Claims.Subject, user.UserId.ToString(), OpenIdConnectConstants.Destinations.AccessToken);
            identity.AddClaim(OpenIdConnectConstants.Claims.Username, user.UserName, OpenIdConnectConstants.Destinations.AccessToken);
            identity.AddClaim(OpenIdConnectConstants.Claims.Email, user.EmailAddress, OpenIdConnectConstants.Destinations.IdentityToken);
            identity.AddClaim(OpenIdConnectConstants.Claims.GivenName, user.FirstName, OpenIdConnectConstants.Destinations.IdentityToken);
            identity.AddClaim(OpenIdConnectConstants.Claims.MiddleName, user.MiddleName, OpenIdConnectConstants.Destinations.IdentityToken);
            identity.AddClaim(OpenIdConnectConstants.Claims.FamilyName, user.LastName, OpenIdConnectConstants.Destinations.IdentityToken);
            identity.AddClaim(OpenIdConnectConstants.Claims.EmailVerified, user.IsEmailConfirmed.ToString(), OpenIdConnectConstants.Destinations.IdentityToken);
            identity.AddClaim(OpenIdConnectConstants.Claims.Audience, "http://localhost:9000", OpenIdConnectConstants.Destinations.AccessToken);

            var principal = new ClaimsPrincipal(identity);

            return SignIn(principal, OpenIdConnectServerDefaults.AuthenticationScheme);
        }

        throw new InvalidOperationException("The specified grant type is not supported.");
    }
}

MVC.AccountController.cs contains Login, GetTokenAsync method.

public class AccountController : Controller
    {
        public static string SecretKey => "MySecretKey";
        public static SymmetricSecurityKey SigningKey => new SymmetricSecurityKey(Encoding.ASCII.GetBytes(SecretKey));

[HttpPost]
        [AllowAnonymous]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Login(LoginVm vm, string returnUrl = null)
        {
            ViewData["ReturnUrl"] = returnUrl;
            if (ModelState.IsValid)
            {
                var token = await GetTokenAsync(vm);

                SecurityToken validatedToken = null;

                TokenValidationParameters validationParameters = new TokenValidationParameters()
                {
                    ValidateIssuer = true,
                    ValidIssuer = "http://localhost:9001/",

                    ValidateAudience = true,
                    ValidAudience = "http://localhost:9000",

                    ValidateLifetime = true,
                    IssuerSigningKey = SigningKey
                };

                JwtSecurityTokenHandler handler = new JwtSecurityTokenHandler();

                try
                {
                    ClaimsPrincipal principal = handler.ValidateToken(token.AccessToken, validationParameters, out validatedToken);
                }
                catch (Exception e)
                {
                    throw;
                }
            }

            return View(vm);
        }

        private async Task<TokenVm> GetTokenAsync(LoginVm vm)
        {
            using (var client = new HttpClient())
            {
                var request = new HttpRequestMessage(HttpMethod.Post, $"http://localhost:9001/Authorization/Token");
                request.Content = new FormUrlEncodedContent(new Dictionary<string, string>
                {
                    ["grant_type"] = "password",
                    ["username"] = vm.EmailAddress,
                    ["password"] = vm.Password
                });

                var response = await client.SendAsync(request, HttpCompletionOption.ResponseContentRead);
                response.EnsureSuccessStatusCode();

                var payload = await response.Content.ReadAsStringAsync();
                //if (payload["error"] != null)
                //    throw new Exception("An error occurred while retriving an access tocken.");                

                return JsonConvert.DeserializeObject<TokenVm>(payload);
            }
        }
}

Error I am getting: "IDX10501: Signature validation failed. Unable to match 'kid': '0-AY7TPAUE2-ZVLUVQMMUJFJ54IMIB70E-XUSYIB', \ntoken: '{\"alg\":\"RS256\",\"typ\":\"JWT\",\"kid\":\"0-AY7TPAUE2-ZVLUVQMMUJFJ54IMIB70E-XUSYIB\"}.{\"sub\":\"10\",\"username\":\"...

Answer 1

See this thread because I was looking for the very same thing (not the exception though), and the accepted answer indeed helps the OP, however, it doesn't help me with : how to create ClaimsPrincipal from JWT Token.

After some research and digging, I've found a way to do it manually (it was my case, I had to do it manually in a specific case).

To do so, first, parse the token with JwtSecurityTokenHandler class :

var token = new JwtSecurityTokenHandler().ReadJwtToken(n.TokenEndpointResponse.AccessToken);

After that, you just ned to create a new ClaimsPrincipal :

var identity = new ClaimsPrincipal(new ClaimsIdentity(token.Claims));

In my specific case, I just have to update claims on my already authenticated user, so I use this code :

var identity = (ClaimsIdentity)User.Identity;
identity.AddClaims(token.Claims);

Hope it will help someone one day if looking after the answer for the title.