在ASP.NET Core中實作一個Token base的身份認證實例

以前在web端的身份認證都是基於Cookie | Session的身份認證, 在沒有更多的終端出現之前，這樣做也沒有什麼問題，但在Web API時代，你所需要面對的就不止是瀏覽器了，還有各種客戶端，這樣就有了一個問題，這些客戶端是不知道cookie是什麼鬼的。 (cookie其實是瀏覽器搞出來的小貓膩，用來保持會話的，但HTTP本身是無狀態的, 各種客戶端能提供的無非也就是HTTP操作的API)

而基於Token的身份認證就是應對這種變化而生的，它更開放，安全性也更高。

基於Token的身份認證有很多種實作方式，但我們這裡只使用微軟提供的API。

接下來的例子將帶領大家完成一個使用微軟JwtSecurityTokenHandler完成一個基於beare token的身份認證。

注意：這種文章屬於Step by step教程，跟著做才不至於看暈，下載完整程式碼分析程式碼結構才有意義。

建立項目

在VS中新建項目，項目類型選擇ASP.NET Core Web Application(.NET Core), 輸入項目名稱為CSTokenBaseAuth

Coding

創建一些輔助類

Coding

創建一些輔助類

Coding

創建一些輔助類

Coding

創建一些輔助類

Coding

創建一些輔助類

Coding

文件夾Auth,並加入RSAKeyHelper.cs以及TokenAuthOption.cs兩個檔案

在RSAKeyHelper.cs

using System.Security.Cryptography;
 
namespace CSTokenBaseAuth.Auth
{
  public class RSAKeyHelper
  {
    public static RSAParameters GenerateKey()
    {
      using (var key = new RSACryptoServiceProvider(2048))
      {
        return key.ExportParameters(true);
      }
    }
  }
}

   

在ConfigureServices中新增以下程式碼：

using System;
using Microsoft.IdentityModel.Tokens;
 
namespace CSTokenBaseAuth.Auth
{
  public class TokenAuthOption
  {
    public static string Audience { get; } = "ExampleAudience";
    public static string Issuer { get; } = "ExampleIssuer";
    public static RsaSecurityKey Key { get; } = new RsaSecurityKey(RSAKeyHelper.GenerateKey());
    public static SigningCredentials SigningCredentials { get; } = new SigningCredentials(Key, SecurityAlgorithms.RsaSha256Signature);
 
    public static TimeSpan ExpiresSpan { get; } = TimeSpan.FromMinutes(20);
  }
}

   

完整的程式碼應該是這樣

services.AddAuthorization(auth =>
{
  auth.AddPolicy("Bearer", new AuthorizationPolicyBuilder()
    .AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme‌)
    .RequireAuthenticatedUser().Build());
});

   

rror用的，比如當身分認證失敗的時候會拋出異常，而這裡就是處理這個異常的。

接下來在相同的方法中加入以下程式碼，

public void ConfigureServices(IServiceCollection services)
{
  // Add framework services.
  services.AddApplicationInsightsTelemetry(Configuration);
  // Enable the use of an [Authorize("Bearer")] attribute on methods and classes to protect.
  services.AddAuthorization(auth =>
  {
    auth.AddPolicy("Bearer", new AuthorizationPolicyBuilder()
      .AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme‌)
      .RequireAuthenticatedUser().Build());
  });
  services.AddMvc();
}

   

應用JwtBearerAuthentication

app.UseExceptionHandler(appBuilder => {
  appBuilder.Use(async (context, next) => {
    var error = context.Features[typeof(IExceptionHandlerFeature)] as IExceptionHandlerFeature;
    //when authorization has failed, should retrun a json message to client
    if (error != null && error.Error is SecurityTokenExpiredException)
    {
      context.Response.StatusCode = 401;
      context.Response.ContentType = "application/json";
      await context.Response.WriteAsync(JsonConvert.SerializeObject(
        new { authenticated = false, tokenExpired = true }
      ));
    }
    //when orther error, retrun a error message json to client
    else if (error != null && error.Error != null)
    {
      context.Response.StatusCode = 500;
      context.Response.ContentType = "application/json";
      await context.Response.WriteAsync(JsonConvert.SerializeObject(
        new { success = false, error = error.Error.Message }
      ));
    }
    //when no error, do next.
    else await next();
  });
});

 

在Controllers中新建一個Web API Controller Class，命名為TokenAuthController.cs。我們將在這裡完成登入授權

在同文件下添加兩個類，分別用來模擬用戶模型，以及用戶存儲，代碼應該是這樣

app.UseExceptionHandler(appBuilder => {
  appBuilder.Use(async (context, next) => {
    var error = context.Features[typeof(IExceptionHandlerFeature)] as IExceptionHandlerFeature;
 
    //when authorization has failed, should retrun a json message to client
    if (error != null && error.Error is SecurityTokenExpiredException)
    {
      context.Response.StatusCode = 401;
      context.Response.ContentType = "application/json";
 
      await context.Response.WriteAsync(JsonConvert.SerializeObject(
        new { authenticated = false, tokenExpired = true }
      ));
    }
    //when orther error, retrun a error message json to client
    else if (error != null && error.Error != null)
    {
      context.Response.StatusCode = 500;
      context.Response.ContentType = "application/json";
      await context.Response.WriteAsync(JsonConvert.SerializeObject(
        new { success = false, error = error.Error.Message }
      ));
    }
    //when no error, do next.
    else await next();
  });
});

   

接下來在TokenAuthController.cs中添加如下方法

app.UseJwtBearerAuthentication(new JwtBearerOptions {
  TokenValidationParameters = new TokenValidationParameters {
    IssuerSigningKey = TokenAuthOption.Key,
    ValidAudience = TokenAuthOption.Audience,
    ValidIssuer = TokenAuthOption.Issuer,
    ValidateIssuerSigningKey = true,
    ValidateLifetime = true,
    ClockSkew = TimeSpan.FromMinutes(0)
  }
});

   

該方法只是產生一個Auth Token,接下來我們來添加另一個方法來調用它

在相同文件中添加如下代碼

using System;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using CSTokenBaseAuth.Auth;
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.IdentityModel.Tokens;
using Microsoft.AspNetCore.Http;
using Newtonsoft.Json;
 
namespace CSTokenBaseAuth
{
  public class Startup
  {
    public Startup(IHostingEnvironment env)
    {
      var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
        .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);
 
      if (env.IsEnvironment("Development"))
      {
        // This will push telemetry data through Application Insights pipeline faster, allowing you to view results immediately.
        builder.AddApplicationInsightsSettings(developerMode: true);
      }
 
      builder.AddEnvironmentVariables();
      Configuration = builder.Build();
    }
 
    public IConfigurationRoot Configuration { get; }
 
    // This method gets called by the runtime. Use this method to add services to the container
    public void ConfigureServices(IServiceCollection services)
    {
      // Add framework services.
      services.AddApplicationInsightsTelemetry(Configuration);
 
      // Enable the use of an [Authorize("Bearer")] attribute on methods and classes to protect.
      services.AddAuthorization(auth =>
      {
        auth.AddPolicy("Bearer", new AuthorizationPolicyBuilder()
          .AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme‌)
          .RequireAuthenticatedUser().Build());
      });
 
      services.AddMvc();
    }
 
    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
      loggerFactory.AddConsole(Configuration.GetSection("Logging"));
      loggerFactory.AddDebug();
 
      app.UseApplicationInsightsRequestTelemetry();
 
      app.UseApplicationInsightsExceptionTelemetry();
 
      #region Handle Exception
      app.UseExceptionHandler(appBuilder => {
        appBuilder.Use(async (context, next) => {
          var error = context.Features[typeof(IExceptionHandlerFeature)] as IExceptionHandlerFeature;
 
          //when authorization has failed, should retrun a json message to client
          if (error != null && error.Error is SecurityTokenExpiredException)
          {
            context.Response.StatusCode = 401;
            context.Response.ContentType = "application/json";
 
            await context.Response.WriteAsync(JsonConvert.SerializeObject(
              new { authenticated = false, tokenExpired = true }
            ));
          }
          //when orther error, retrun a error message json to client
          else if (error != null && error.Error != null)
          {
            context.Response.StatusCode = 500;
            context.Response.ContentType = "application/json";
            await context.Response.WriteAsync(JsonConvert.SerializeObject(
              new { success = false, error = error.Error.Message }
            ));
          }
          //when no error, do next.
          else await next();
        });
      });
      #endregion
 
      #region UseJwtBearerAuthentication
      app.UseJwtBearerAuthentication(new JwtBearerOptions {
        TokenValidationParameters = new TokenValidationParameters {
          IssuerSigningKey = TokenAuthOption.Key,
          ValidAudience = TokenAuthOption.Audience,
          ValidIssuer = TokenAuthOption.Issuer,
          ValidateIssuerSigningKey = true,
          ValidateLifetime = true,
          ClockSkew = TimeSpan.FromMinutes(0)
        }
      });
      #endregion
 
      app.UseMvc(routes =>
      {
        routes.MapRoute(
          name: "default",
          template: "{controller=Login}/{action=Index}");
      });
    }
  }
}

 這樣

public class User
{
  public Guid ID { get; set; }
  public string Username { get; set; }
  public string Password { get; set; }
}
 
public static class UserStorage
{
  public static List<User> Users { get; set; } = new List<User> {
    new User {ID=Guid.NewGuid(),Username="user1",Password = "user1psd" },
    new User {ID=Guid.NewGuid(),Username="user2",Password = "user2psd" },
    new User {ID=Guid.NewGuid(),Username="user3",Password = "user3psd" }
  };
}

   

接下來我們來完成授權驗證部分

在Controllers中新建一個Web API Controller Class，命名為ValuesController.r

在其中添加如下碼裝飾屬性

private string GenerateToken(User user, DateTime expires)
{
  var handler = new JwtSecurityTokenHandler();
   
  ClaimsIdentity identity = new ClaimsIdentity(
    new GenericIdentity(user.Username, "TokenAuth"),
    new[] {
      new Claim("ID", user.ID.ToString())
    }
  );
 
  var securityToken = handler.CreateToken(new SecurityTokenDescriptor
  {
    Issuer = TokenAuthOption.Issuer,
    Audience = TokenAuthOption.Audience,
    SigningCredentials = TokenAuthOption.SigningCredentials,
    Subject = identity,
    Expires = expires
  });
  return handler.WriteToken(securityToken);
}

   

最後讓我們來新增視圖

在Controllers中新建一個Web Controller Class，命名為LoginController.cs下新建一個名為Login的目錄，並在其中新建一個Index.cshtml檔案。

程式碼應該是這個樣子

[HttpPost]
public string GetAuthToken(User user)
{
  var existUser = UserStorage.Users.FirstOrDefault(u => u.Username == user.Username && u.Password == user.Password);
 
  if (existUser != null)
  {
    var requestAt = DateTime.Now;
    var expiresIn = requestAt + TokenAuthOption.ExpiresSpan;
    var token = GenerateToken(existUser, expiresIn);
 
    return JsonConvert.SerializeObject(new {
      stateCode = 1,
      requertAt = requestAt,
      expiresIn = TokenAuthOption.ExpiresSpan.TotalSeconds,
      accessToken = token
    });
  }
  else
  {
    return JsonConvert.SerializeObject(new { stateCode = -1, errors = "Username or password is invalid" });
  }
}

   

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