如何获取ASP.NETCoreToken的认证

如何获取ASP.NETCoreToken的认证，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

令牌认证（Token Authentication）已经成为单页应用（SPA）和移动应用事实上的标准。即使是传统的B/S应用也能利用其优点。优点很明白：极少的服务端数据管理、可扩展性、可以使用单独的认证服务器和应用服务器分离。

如果你对令牌（token）不是太了解，可以看这篇文章（ overview of token authentication and JWTs）

令牌认证在asp.net core中集成。其中包括保护Bearer Jwt的路由功能，但是移除了生成token和验证token的部分，这些可以自定义或者使用第三方库来实现，得益于此，MVC和Web api项目可以使用令牌认证，而且很简单。下面将一步一步实现，代码可以在（ 源码）下载。

ASP.NET Core令牌验证

首先，背景知识：认证令牌，例如JWTs，是通过http 认证头传递的，例如：

GET /fooAuthorization: Bearer [token]

令牌可以通过浏览器cookies。传递方式是header或者cookies取决于应用和实际情况，对于移动app，使用headers，对于web，推荐在html5 storage中使用cookies，来防止xss攻击。

asp.net core对jwts令牌的验证很简单，特别是你通过header传递。

1、生成 SecurityKey，这个例子，我生成对称密钥验证jwts通过HMAC-SHA256加密方式，在startup.cs中：

// secretKey contains a secret passphrase only your server knowsvar secretKey = "mysupersecret_secretkey!123";var signingKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(secretKey));

验证 header中传递的JWTs

在 Startup.cs中，使用Microsoft.AspNetCore.Authentication.JwtBearer中的UseJwtBearerAuthentication 方法获取受保护的api或者mvc路由有效的jwt。

var tokenValidationParameters = new TokenValidationParameters{  // The signing key must match!  ValidateIssuerSigningKey = true,  IssuerSigningKey = signingKey,  // Validate the JWT Issuer (iss) claim  ValidateIssuer = true,  ValidIssuer = "ExampleIssuer",  // Validate the JWT Audience (aud) claim  ValidateAudience = true,  ValidAudience = "ExampleAudience",  // Validate the token expiry  ValidateLifetime = true,  // If you want to allow a certain amount of clock drift, set that here:  ClockSkew = TimeSpan.Zero};app.UseJwtBearerAuthentication(new JwtBearerOptions{  AutomaticAuthenticate = true,  AutomaticChallenge = true,  TokenValidationParameters = tokenValidationParameters});

通过这个中间件，任何[Authorize]的请求都需要有效的jwt：

签名有效；

过期时间；

有效时间；

Issuer 声明等于"ExampleIssuer"

订阅者声明等于 "ExampleAudience"

如果不是合法的JWT，请求终止，issuer声明和订阅者声明不是必须的，它们用来标识应用和客户端。

在cookies中验证JWTs

ASP.NET Core中的cookies 认证不支持传递jwt。需要自定义实现 ISecureDataFormat接口的类。现在，你只是验证token，不是生成它们，只需要实现Unprotect方法，其他的交给System.IdentityModel.Tokens.Jwt.JwtSecurityTokenHandler这个类处理。

using System;using System.IdentityModel.Tokens.Jwt;using System.Security.Claims;using Microsoft.AspNetCore.Authentication;using Microsoft.AspNetCore.Http.Authentication;using Microsoft.IdentityModel.Tokens; namespace SimpleTokenProvider{  public class CustomJwtDataFormat : ISecureDataFormat  {    private readonly string algorithm;    private readonly TokenValidationParameters validationParameters;     public CustomJwtDataFormat(string algorithm, TokenValidationParameters validationParameters)    {      this.algorithm = algorithm;      this.validationParameters = validationParameters;    }     public AuthenticationTicket Unprotect(string protectedText)      => Unprotect(protectedText, null);     public AuthenticationTicket Unprotect(string protectedText, string purpose)    {      var handler = new JwtSecurityTokenHandler();      ClaimsPrincipal principal = null;      SecurityToken validToken = null;       try      {        principal = handler.ValidateToken(protectedText, this.validationParameters, out validToken);         var validJwt = validToken as JwtSecurityToken;         if (validJwt == null)        {          throw new ArgumentException("Invalid JWT");        }         if (!validJwt.Header.Alg.Equals(algorithm, StringComparison.Ordinal))        {          throw new ArgumentException($"Algorithm must be '{algorithm}'");        }         // Additional custom validation of JWT claims here (if any)      }      catch (SecurityTokenValidationException)      {        return null;      }      catch (ArgumentException)      {        return null;      }       // Validation passed. Return a valid AuthenticationTicket:      return new AuthenticationTicket(principal, new AuthenticationProperties(), "Cookie");    }     // This ISecureDataFormat implementation is decode-only    public string Protect(AuthenticationTicket data)    {      throw new NotImplementedException();    }     public string Protect(AuthenticationTicket data, string purpose)    {      throw new NotImplementedException();    }  }}

在startup.cs中调用

var tokenValidationParameters = new TokenValidationParameters{  // The signing key must match!  ValidateIssuerSigningKey = true,  IssuerSigningKey = signingKey,   // Validate the JWT Issuer (iss) claim  ValidateIssuer = true,  ValidIssuer = "ExampleIssuer",   // Validate the JWT Audience (aud) claim  ValidateAudience = true,  ValidAudience = "ExampleAudience",   // Validate the token expiry  ValidateLifetime = true,   // If you want to allow a certain amount of clock drift, set that here:  ClockSkew = TimeSpan.Zero}; app.UseCookieAuthentication(new CookieAuthenticationOptions{  AutomaticAuthenticate = true,  AutomaticChallenge = true,  AuthenticationScheme = "Cookie",  CookieName = "access_token",  TicketDataFormat = new CustomJwtDataFormat(    SecurityAlgorithms.HmacSha256,    tokenValidationParameters)});

如果请求中包含名为access_token的cookie验证为合法的JWT，这个请求就能返回正确的结果，如果需要，你可以加上额外的jwt chaims,或者复制jwt chaims到ClaimsPrincipal在CustomJwtDataFormat.Unprotect方法中，上面是验证token，下面将在asp.net core中生成token。

ASP.NET Core生成Tokens

在asp.net 4.5中，这个UseOAuthAuthorizationServer中间件可以轻松的生成tokens，但是在asp.net core取消了，下面写一个简单的token生成中间件，最后，有几个现成解决方案的链接，供你选择。

简单的token生成节点

首先，生成 POCO保存中间件的选项. 生成类：TokenProviderOptions.cs

using System;using Microsoft.IdentityModel.Tokens; namespace SimpleTokenProvider{  public class TokenProviderOptions  {    public string Path { get; set; } = "/token";     public string Issuer { get; set; }     public string Audience { get; set; }     public TimeSpan Expiration { get; set; } = TimeSpan.FromMinutes(5);     public SigningCredentials SigningCredentials { get; set; }  }}

现在自己添加一个中间件，asp.net core 的中间件类一般是这样的：

using System.IdentityModel.Tokens.Jwt;using System.Security.Claims;using System.Threading.Tasks;using Microsoft.AspNetCore.Http;using Microsoft.Extensions.Options;using Newtonsoft.Json;namespace SimpleTokenProvider{  public class TokenProviderMiddleware  {    private readonly RequestDelegate _next;    private readonly TokenProviderOptions _options;    public TokenProviderMiddleware(      RequestDelegate next,      IOptions options)    {      _next = next;      _options = options.Value;    }    public Task Invoke(HttpContext context)    {      // If the request path doesn't match, skip      if (!context.Request.Path.Equals(_options.Path, StringComparison.Ordinal))      {        return _next(context);      }      // Request must be POST with Content-Type: application/x-www-form-urlencoded      if (!context.Request.Method.Equals("POST")        || !context.Request.HasFormContentType)      {        context.Response.StatusCode = 400;        return context.Response.WriteAsync("Bad request.");      }      return GenerateToken(context);    }  }}

这个中间件类接受TokenProviderOptions作为参数，当有请求且请求路径是设置的路径（token或者api/token），Invoke方法执行，token节点只对 POST请求而且包括form-urlencoded内容类型（Content-Type: application/x-www-form-urlencoded），因此调用之前需要检查下内容类型。

最重要的是GenerateToken，这个方法需要验证用户的身份，生成jwt，传回jwt：

private async Task GenerateToken(HttpContext context){  var username = context.Request.Form["username"];  var password = context.Request.Form["password"];   var identity = await GetIdentity(username, password);  if (identity == null)  {    context.Response.StatusCode = 400;    await context.Response.WriteAsync("Invalid username or password.");    return;  }   var now = DateTime.UtcNow;   // Specifically add the jti (random nonce), iat (issued timestamp), and sub (subject/user) claims.  // You can add other claims here, if you want:  var claims = new Claim[]  {    new Claim(JwtRegisteredClaimNames.Sub, username),    new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),    new Claim(JwtRegisteredClaimNames.Iat, ToUnixEpochDate(now).ToString(), ClaimValueTypes.Integer64)  };   // Create the JWT and write it to a string  var jwt = new JwtSecurityToken(    issuer: _options.Issuer,    audience: _options.Audience,    claims: claims,    notBefore: now,    expires: now.Add(_options.Expiration),    signingCredentials: _options.SigningCredentials);  var encodedJwt = new JwtSecurityTokenHandler().WriteToken(jwt);   var response = new  {    access_token = encodedJwt,    expires_in = (int)_options.Expiration.TotalSeconds  };   // Serialize and return the response  context.Response.ContentType = "application/json";  await context.Response.WriteAsync(JsonConvert.SerializeObject(response, new JsonSerializerSettings { Formatting = Formatting.Indented }));}

大部分代码都很官方，JwtSecurityToken 类生成jwt，JwtSecurityTokenHandler将jwt编码，你可以在claims中添加任何chaims。验证用户身份只是简单的验证，实际情况肯定不是这样的，你可以集成 identity framework或者其他的，对于这个实例只是简单的硬编码：

private Task GetIdentity(string username, string password){  // DON'T do this in production, obviously!  if (username == "TEST" && password == "TEST123")  {    return Task.FromResult(new ClaimsIdentity(new System.Security.Principal.GenericIdentity(username, "Token"), new Claim[] { }));  }   // Credentials are invalid, or account doesn't exist  return Task.FromResult(null);}

添加一个将DateTime生成timestamp的方法：

public static long ToUnixEpochDate(DateTime date)  => (long)Math.Round((date.ToUniversalTime() - new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero)).TotalSeconds);

现在，你可以将这个中间件添加到startup.cs中了：

using System.Text;using Microsoft.AspNetCore.Builder;using Microsoft.AspNetCore.Hosting;using Microsoft.Extensions.Configuration;using Microsoft.Extensions.DependencyInjection;using Microsoft.Extensions.Logging;using Microsoft.Extensions.Options;using Microsoft.IdentityModel.Tokens; namespace SimpleTokenProvider{  public partial class Startup  {    public Startup(IHostingEnvironment env)    {      var builder = new ConfigurationBuilder()        .AddJsonFile("appsettings.json", optional: true);      Configuration = builder.Build();    }     public IConfigurationRoot Configuration { get; set; }     public void ConfigureServices(IServiceCollection services)    {      services.AddMvc();    }     // The secret key every token will be signed with.    // In production, you should store this securely in environment variables    // or a key management tool. Don't hardcode this into your application!    private static readonly string secretKey = "mysupersecret_secretkey!123";     public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)    {      loggerFactory.AddConsole(LogLevel.Debug);      loggerFactory.AddDebug();       app.UseStaticFiles();       // Add JWT generation endpoint:      var signingKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(secretKey));      var options = new TokenProviderOptions      {        Audience = "ExampleAudience",        Issuer = "ExampleIssuer",        SigningCredentials = new SigningCredentials(signingKey, SecurityAlgorithms.HmacSha256),      };       app.UseMiddleware(Options.Create(options));       app.UseMvc();    }  }}

测试一下，推荐使用chrome 的postman：

POST /tokenContent-Type: application/x-www-form-urlencodedusername=TEST&password=TEST123

结果：
OK

Content-Type: application/json

{
"access_token": "eyJhb...",
"expires_in": 300
}

你可以使用jwt工具查看生成的jwt内容。如果开发的是移动应用或者单页应用，你可以在后续请求的header中存储jwt，如果你需要在cookies中存储的话，你需要对代码修改一下，需要将返回的jwt字符串添加到cookie中。
测试下：

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