Implementation of an Token base Authentication Instance in ASP. NET Core

In the past, the identity authentication on web was based on Cookie Session, and there was no problem in doing so before more terminals appeared. However, in the era of Web API, you need to face not only browsers, but also various clients, so there is a problem. These clients don't know what cookie is. (cookie is actually a little trick made by the browser, which is used to keep the conversation, but HTTP itself is stateless, and all kinds of clients can provide nothing more than API operated by HTTP)

The identity authentication based on Token is born in response to this change, which is more open and secure.

There are many ways to implement Token-based identity authentication, but we only use API provided by Microsoft here.

The following example will lead you to complete an identity authentication based on beare token using Microsoft JwtSecurityTokenHandler.

Note: This article belongs to Step by step tutorial, follow to do not look dizzy, download the complete code analysis code structure is meaningful.

Pre-preparation

It is recommended to use VS2015 Update3 as your IDE. Download address: https://www.ofstack.com/softjc/446184. html

You need to install the running environment and development tools of. NET Core. The version of VS is available here: https://www.ofstack.com/softs/472362. html

Create a project

Create a new project in VS, select ASP. NET Core Web Application (. NET Core) as the project type, and enter the project name as CSTokenBaseAuth

Coding

Create 1 helper classes

Create a folder Auth under the project root directory and add two files RSAKeyHelper. cs and TokenAuthOption. cs

In 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);
      }
    }
  }
}

In TokenAuthOption. cs

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);
  }
}

Startup.cs

Add the following code to ConfigureServices:

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

The complete code should look like this

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();
}

Add the following code to the Configure method

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();
  });
});

This code is mainly used by Handle Error, for example, when the identity authentication fails, an exception will be thrown, and this is the handling of this exception.

Next, add the following code to the same method,

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();
  });
});

Applying JwtBearerAuthentication

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

The complete code should look like this

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}");
      });
    }
  }
}

Create a new Web API Controller Class in Controllers, and name it TokenAuthController. cs. We will complete the login authorization here

Add two classes under the same file, which are used to simulate the user model and the user store. The code should look like this

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" }
  };
}

Next, add the following method in TokenAuthController. cs

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);
}

This method only generates an Auth Token, so let's add another method to call it

Add the following code to the same file

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);
  }
}

0

The complete code of this file should look like this

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);
  }
}

1

Next, let's complete the authorization verification section

Create a new Web API Controller Class in Controllers and name it ValuesController. cs

Add the following code to it

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);
  }
}

2

Add decorative properties to methods

[HttpGet]
[Authorize("Bearer")]

 The complete file code should look like this 
using System.Linq;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Authorization;
using System.Security.Claims;

namespace CSTokenBaseAuth.Controllers
{
  [Route("api/[controller]")]
  public class ValuesController : Controller
  {
    [HttpGet]
    [Authorize("Bearer")]
    public string Get()
    {
      var claimsIdentity = User.Identity as ClaimsIdentity;

      var id = claimsIdentity.Claims.FirstOrDefault(c => c.Type == "ID").Value;

      return $"Hello! {HttpContext.User.Identity.Name}, your ID is:{id}";
    }
  }
}

Finally, let's add a view

Create a new Web Controller Class in Controllers and name it LoginController. cs

The code should look like this

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);
  }
}

4

Create a new directory named Login under the project Views directory, and create a new Index. cshtml file in it.

The code should look like this

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);
  }
}

5