目前，Blazor WebAssembly 8自有身份验证尚处于实验阶段，官方尚未提供明确的示例代码。但是，下面是一个基本的示例，以帮助您开始使用Blazor WebAssembly进行自有身份验证：

1. 创建一个新的Blazor WebAssembly项目。

2. 在项目中打开“Startup.cs”文件，并添加以下代码：

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Components.Authorization;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Configuration;
using System;
using System.Net.Http;
using System.Threading.Tasks;

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

        public IConfiguration Configuration { get; }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddAuthenticationCore();
            services.AddScoped();
            services.AddScoped(); // Replace with your own login service
            services.AddScoped(); // Replace with your own logout service
            services.AddScoped();
            services.AddScoped(); // Replace with your own login service
            services.AddScoped(); // Replace with your own logout service
            services.AddScoped();
            services.AddScoped(); // Replace with your own login service
            services.AddScoped(); // Replace with your own logout service
            services.AddAuthorizationCore();
            services.AddScoped();
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            app.UseAuthentication();
            app.UseAuthorization();

            app.UseBlazorFrameworkFiles();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapRazorPages();
                endpoints.MapControllers();
                endpoints.MapFallbackToFile("index.html");
            });
        }
    }
}

3. 创建一个名为ServerAuthenticationStateProvider.cs的新类，并添加以下代码：

using Microsoft.AspNetCore.Components.Authorization;
using System.Security.Claims;
using System.Threading.Tasks;

namespace YourProjectNamespace
{
    public class ServerAuthenticationStateProvider : AuthenticationStateProvider
    {
        public override Task GetAuthenticationStateAsync()
        {
            var identity = new ClaimsIdentity(new[]
            {
                new Claim(ClaimTypes.Name, "John Doe"),
            }, "Fake authentication type");

            var user = new ClaimsPrincipal(identity);

            return Task.FromResult(new AuthenticationState(user));
        }
    }
}

4. 创建一个名为FakeLoginService.cs的新类，并添加以下代码：

using System.Threading.Tasks;

namespace YourProjectNamespace
{
    public interface ILoginService
    {
        Task LoginAsync();
    }

    public class FakeLoginService : ILoginService
    {
        public Task LoginAsync()
        {
            // Add your authentication logic here
            return Task.CompletedTask;
        }
    }
}

5. 创建一个名为FakeLogoutService.cs的新类，并添加以下代码：

using System.Threading.Tasks;

namespace YourProjectNamespace
{
    public interface ILogoutService
    {
        Task LogoutAsync();
    }

    public class FakeLogoutService : ILogoutService
    {
        public Task LogoutAsync()
        {
            // Add your logout logic here
            return Task.CompletedTask;
        }
    }
}

请注意，上述示例中的FakeLoginService和FakeLogoutService是用于演示目的的占位符服务，您需要替换为实际的登录和注销逻辑。

这只是一个基本示例，您可以根据自己的需求进行修改和扩展。可以根据您的身份验证需求调整配置和实现。