HTTP基本认证
在HTTP中，HTTP基本认证（Basic Authentication）是一种允许浏览器或其他客户端程序使用（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基本认证协议
- 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，一般部署在互信的内网，在公网上应用BA协议通常与https结合。
BA标准协议
BA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 UnauthorizedWWW-Authenticate: Basic realm="our site"
或在初次请求时发送正确Authorization标头，从而避免被质询
② 客户端以based64(用户名:口令) 作为Authorization标头值，重新发送请求：
Authorization: Basic userid:password
认证的范围与realm相关，准确的realm由服务端定义，因为服务端可能有多个不同的realm.
BA编程实践
ASP.NET Core网站利用FileServerMiddleware将部分路径映射到文件资源，对该资源访问路径应用Http基本认证。
服务端实现BA认证
① 实现基本认证Handler：认证、无口令质询、质询失败逻辑
# ......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> /// 认证逻辑 /// </summary> 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[0]; password = credentials[1]; 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> 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> 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); } }}
② 实现BasicAuthenticationMiddleware: 要求对HttpContext应用BA Scheme。
// 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); }}
③ ASP.NET Core 添加BA Scheme , 为待认证资源路径启用BA中间件，注意这里使用UseWhen插入中间件。
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()；} );
现可在浏览器测试：
进一步思考？
以上是浏览器在BA协议中的行为：可尝试程序自动向服务端发起BA请求，需要的同学看博客园源码。
That's All . BA认证是常见的基础认证协议，文章期待以清晰的方式传递协议原理和编程实现。
