下面是一个使用ASP.NET Core 8和Duende Identity Server进行认证的解决方案，包括OpenIdConnect、Cookies和JWT的代码示例。

1. 首先，确保你已经安装了Microsoft.AspNetCore.Authentication和Duende.IdentityServer NuGet包。

2. 在Startup.cs文件中配置Identity Server和认证中间件：

using Duende.IdentityServer;
using Duende.IdentityServer.Models;
using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Authentication.OpenIdConnect;
using Microsoft.IdentityModel.Tokens;

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllersWithViews();

        // 配置Identity Server
        services.AddIdentityServer()
            .AddDeveloperSigningCredential()
            .AddInMemoryApiScopes(Config.ApiScopes)
            .AddInMemoryClients(Config.Clients);

        // 配置认证中间件
        services.AddAuthentication(options =>
            {
                options.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
                options.DefaultChallengeScheme = OpenIdConnectDefaults.AuthenticationScheme;
            })
            .AddCookie()
            .AddOpenIdConnect(options =>
            {
                options.Authority = "https://identityserver.example.com";
                options.ClientId = "your-client-id";
                options.ClientSecret = "your-client-secret";
                options.ResponseType = "code";
                options.Scope.Add("openid");
                options.Scope.Add("profile");
                options.SaveTokens = true;
                options.GetClaimsFromUserInfoEndpoint = true;
                options.TokenValidationParameters = new TokenValidationParameters
                {
                    NameClaimType = "name"
                };
            });
    }

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

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

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapDefaultControllerRoute();
        });
    }
}

3. 创建一个Config.cs文件来定义API范围和客户端配置：

using Duende.IdentityServer.Models;

public static class Config
{
    public static IEnumerable ApiScopes => new List
    {
        new ApiScope("api1", "API 1")
    };

    public static IEnumerable Clients => new List
    {
        new Client
        {
            ClientId = "your-client-id",
            ClientSecrets = { new Secret("your-client-secret".Sha256()) },
            AllowedGrantTypes = GrantTypes.Code,
            RequirePkce = true,
            RedirectUris = { "https://your-app.com/signin-oidc" },
            PostLogoutRedirectUris = { "https://your-app.com/signout-callback-oidc" },
            AllowedScopes = { "openid", "profile", "api1" },
            AllowOfflineAccess = true
        }
    };
}

4. 在控制器中添加一个需要认证的路由：

[Authorize]
public class HomeController : Controller
{
    public IActionResult Index()
    {
        return View();
    }
}

5. 在视图中添加一个链接来触发认证过程：

@using Microsoft.AspNetCore.Authentication

@if (User.Identity.IsAuthenticated)
{
    
Welcome, @User.Identity.Name!
    

        Logout
    
}
else
{
    
Login
}

这是一个简单的使用ASP.NET Core 8和Duende Identity Server进行认证的示例。你可以根据自己的需求进行调整和扩展。