The name 'CertificateAuthenticationDefaults' does not exist in the current context

Question

I'm trying to configure mTLS authentication with ASP.NET core 3.1 by using the example from Microsoft Docs but getting the error below

Error CS0103 The name 'CertificateAuthenticationDefaults' does not exist in the current context

The code I'm using for Startup.cs is below:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.AspNetCore.HttpOverrides;
using System.Net;
using System.Security.Cryptography.X509Certificates;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using WebApplication1.Data;

namespace WebApplication1
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<ApplicationDbContext>(options =>
                options.UseSqlServer(
                    Configuration.GetConnectionString("DefaultConnection")));
            services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
                .AddEntityFrameworkStores<ApplicationDbContext>();
            services.AddControllersWithViews();
            services.AddRazorPages();

            services.AddControllersWithViews();
            // Configure the application to use the protocol and client ip address forwared by the frontend load balancer
            services.Configure<ForwardedHeadersOptions>(options =>
            {
                options.ForwardedHeaders =
                    ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
            });

            // Configure the application to client certificate forwarded the frontend load balancer
            services.AddCertificateForwarding(options => { options.CertificateHeader = "X-ARR-ClientCert"; });

            // Add certificate authentication so when authorization is performed the user will be created from the certificate
            services.AddAuthentication(CertificateAuthenticationDefaults.AuthenticationScheme).AddCertificate();

        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseForwardedHeaders();
            app.UseCertificateForwarding();
            app.UseHttpsRedirection();

            app.UseRouting();
            app.UseStaticFiles();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
                endpoints.MapRazorPages();
            });
        }
    }


}

Any suggestinos on fix will be appreciated

Answer 1

In order to overcome the error I have to add the following statement in the code :

using Microsoft.AspNetCore.Authentication.Certificate;

and install Microsoft.AspNetCore.Authentication.Certificate 3.1.20 package.