ASP.NET Core编程实现基本身份认证

HTTP基本认证

在HTTP中，HTTP基本认证（Basic Authentication）是一种允许网页浏览器或其他客户端程序以(用户名：口令) 请求资源的身份验证方式，不要求cookie,session identifier、login page等标记或载体。

-  所有浏览器据支持HTTP基本认证方式

-  基本身证原理不保证传输凭证的安全性，仅被based64编码，并没有encrypted或者hashed，一般部署在客户端和服务端互信的网络，在公网中应用BA认证通常与https结合

https://en.wikipedia.org/wiki/Basic_access_authentication

BA标准协议

BA认证协议的实施主要依靠约定的请求头/响应头， 典型的浏览器和服务器的BA认证流程：

① 浏览器请求应用了BA协议的网站，服务端响应一个401认证失败响应码，并写入WWW-Authenticate响应头，指示服务端支持BA协议

HTTP/1.1 401 Unauthorized
WWW-Authenticate: Basic realm="our site"     # WWW-Authenticate响应头包含一个realm域属性，指明HTTP基本认证的是这个资源集

或客户端在第一次请求时发送正确Authorization标头，从而避免被质询

②  客户端based64(用户名：口令），作为Authorization标头值 重新发送请求。

Authorization: Basic userid:password

所以在HTTP基本认证中认证范围与 realm有关（具体由服务端定义）

>  一般浏览器客户端对于www-Authenticate质询结果，会弹出口令输入窗.

BA编程实践

aspnetcore网站利用FileServerMiddleware 将路径映射到某文件资源， 现对该 文件资源访问路径应用 Http BA协议。

ASP.NET Core服务端实现BA认证：

①  实现服务端基本认证的认证过程、质询逻辑

②  实现基本身份认证交互中间件BasicAuthenticationMiddleware ,要求对HttpContext使用 BA.Scheme

③  ASP.NET Core 添加认证计划 , 为文件资源访问路径启用 BA中间件，注意使用UseWhen插入中间件

using System;
using System.Net.Http.Headers;
using System.Security.Claims;
using System.Text;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authentication;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace EqidManager.Services
{
    public static class BasicAuthenticationScheme
    {
        public const string DefaultScheme = "Basic";
    }

    public class BasicAuthenticationOption:AuthenticationSchemeOptions
    {
        public string Realm { get; set; }
        public string UserName { get; set; }
        public string UserPwd { get; set; }
    }

    public class BasicAuthenticationHandler : AuthenticationHandler<BasicAuthenticationOption>
    {
        private readonly BasicAuthenticationOption authOptions;
        public BasicAuthenticationHandler(
            IOptionsMonitor<BasicAuthenticationOption> options,
            ILoggerFactory logger,
            UrlEncoder encoder,
            ISystemClock clock)
            : base(options, logger, encoder, clock)
        {
            authOptions = options.CurrentValue;
        }

        /// <summary>
        /// 认证
        /// </summary>
        /// <returns></returns>
        protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
        {
            if (!Request.Headers.ContainsKey("Authorization"))
                return AuthenticateResult.Fail("Missing Authorization Header");
            string username, password;
            try
            {
                var authHeader = AuthenticationHeaderValue.Parse(Request.Headers["Authorization"]);
                var credentialBytes = Convert.FromBase64String(authHeader.Parameter);
                var credentials = Encoding.UTF8.GetString(credentialBytes).Split(':');
                 username = credentials[];
                 password = credentials[];
                 var isValidUser= IsAuthorized(username,password);
                if(isValidUser== false)
                {
                    return AuthenticateResult.Fail("Invalid username or password");
                }
            }
            catch
            {
                return AuthenticateResult.Fail("Invalid Authorization Header");
            }

            var claims = new[] {
                new Claim(ClaimTypes.NameIdentifier,username),
                new Claim(ClaimTypes.Name,username),
            };
            var identity = new ClaimsIdentity(claims, Scheme.Name);
            var principal = new ClaimsPrincipal(identity);
            var ticket = new AuthenticationTicket(principal, Scheme.Name);
            return await Task.FromResult(AuthenticateResult.Success(ticket));
        }

        /// <summary>
        /// 质询
        /// </summary>
        /// <param name="properties"></param>
        /// <returns></returns>
        protected override async Task HandleChallengeAsync(AuthenticationProperties properties)
        {
            Response.Headers["WWW-Authenticate"] = $"Basic realm=\"{Options.Realm}\"";
            await base.HandleChallengeAsync(properties);
        }

        /// <summary>
        /// 认证失败
        /// </summary>
        /// <param name="properties"></param>
        /// <returns></returns>
        protected override async Task HandleForbiddenAsync(AuthenticationProperties properties)
        {
           await base.HandleForbiddenAsync(properties);
        }

        private bool IsAuthorized(string username, string password)
        {
            return username.Equals(authOptions.UserName, StringComparison.InvariantCultureIgnoreCase)
                   && password.Equals(authOptions.UserPwd);
        }
    }
}

// HTTP基本认证Middleware
 public static class BasicAuthentication
 {
        public static void UseBasicAuthentication(this IApplicationBuilder app)
        {
            app.UseMiddleware<BasicAuthenticationMiddleware>();
        }
 }

public class BasicAuthenticationMiddleware
{
     private readonly RequestDelegate _next;
     private readonly ILogger _logger;

     public BasicAuthenticationMiddleware(RequestDelegate next, ILoggerFactory LoggerFactory)
     {
        _next = next;
        _logger = LoggerFactory.CreateLogger<BasicAuthenticationMiddleware>();
     }
     public async Task Invoke(HttpContext httpContext, IAuthenticationService authenticationService)
     {
       var authenticated = await authenticationService.AuthenticateAsync(httpContext, BasicAuthenticationScheme.DefaultScheme);
       _logger.LogInformation("Access Status：" + authenticated.Succeeded);
       if (!authenticated.Succeeded)
       {
           await authenticationService.ChallengeAsync(httpContext, BasicAuthenticationScheme.DefaultScheme, new AuthenticationProperties { });
           return;
       }
       await _next(httpContext);
     }
}

Startup.cs 文件添加并启用HTTP基本认证

services.AddAuthentication(BasicAuthenticationScheme.DefaultScheme)
                .AddScheme<BasicAuthenticationOption, BasicAuthenticationHandler>(BasicAuthenticationScheme.DefaultScheme,null);

app.UseWhen(
            predicate:x => x.Request.Path.StartsWithSegments(new PathString(_protectedResourceOption.Path)),
            configuration:appBuilder => { appBuilder.UseBasicAuthentication()； }
    ); 

以上BA认证的服务端已经完成，现在可以在浏览器测试：

进一步思考？

浏览器在BA协议中行为： 编程实现BA客户端，要的同学可以直接拿去

    /// <summary>
    /// BA认证请求Handler
    /// </summary>
    public class BasicAuthenticationClientHandler : HttpClientHandler
    {
        public static string BAHeaderNames = "authorization";
        private RemoteBasicAuth _remoteAccount;

        public BasicAuthenticationClientHandler(RemoteBasicAuth remoteAccount)
        {
            _remoteAccount = remoteAccount;
            AllowAutoRedirect = false;
            UseCookies = true;
        }

        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            var authorization = $"{_remoteAccount.UserName}:{_remoteAccount.Password}";
            var authorizationBased64 = "Basic " + Convert.ToBase64String(new ASCIIEncoding().GetBytes(authorization));
            request.Headers.Remove(BAHeaderNames);
            request.Headers.Add(BAHeaderNames, authorizationBased64);
            return base.SendAsync(request, cancellationToken);
        }
    }

  // 生成basic Authentication请求
            services.AddHttpClient("eqid-ba-request", x =>
                   x.BaseAddress = new Uri(_proxyOption.Scheme +"://"+ _proxyOption.Host+":"+_proxyOption.Port ) )
               .ConfigurePrimaryHttpMessageHandler(y => new BasicAuthenticationClientHandler(_remoteAccount){} )
               .SetHandlerLifetime(TimeSpan.FromMinutes());

仿BA认证协议中的浏览器行为

That's All .  BA认证是随处可见的基础认证协议，本文期待以最清晰的方式帮助你理解协议:

实现了基本认证协议服务端，客户端；

作者：JulianHuang

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