ASP.NET Core – JWT认证实现_C#

一、JWT结构

　JWT介绍就太多了，这里主要关注下Jwt的结构。　

　Jwt中包含三个部分：Header（头部）.Payload（负载）.Signature（签名）

Header：描述 JWT 的元数据的JSON对象，如：
```
{"alg":"HS256","typ":"JWT"}
```

Payload：一个用来存放实际需要传递的数据的JSON 对象。如：

"http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name": "admin",
    "exp": 1610877510,
    "iss": "cba",
    "aud": "cba"
}

Signature：对前两部分（Header、Payload）的签名，防止数据篡改。
```
HMACSHA256(base64UrlEncode(header) + "." + base64UrlEncode(payload), secret)
```

　　JWT示例：

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJodHRwOi8vc2NoZW1hcy54bWxzb2FwLm9yZy93cy8yMDA1LzA1L2lkZW50aXR5L2NsYWltcy9uYW1lIjoiYWRtaW4iLCJleHAiOjE2MTA4Nzc1MTAsImlzcyI6ImNiYSIsImF1ZCI6ImNiYSJ9.O9lbZwfqRuA6vKcRCfYieA1zLkTPppdSvTc8UzwCkNw

二、ASP.NET Core 使用JTW认证

　1、添加Nuget包引用：

dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer

　2、定义一个JwtSettingDto结构，用于读取JWT配置信息

public class JwtSetting
{
    /// <summary>
    /// 发行者
    /// </summary>
    public string Issuer { get; set; }
    /// <summary>
    /// 受众
    /// </summary>
    public string Audience { get; set; }
    /// <summary>
    /// 秘钥
    /// </summary>
    public string SecretKey { get; set; }
    /// <summary>
    /// 过期时间
    /// </summary>
    public int AccessExpiration { get; set; }
    /// <summary>
    /// 刷新时间
    /// </summary>
    public int RefreshExpiration { get; set; }
}

　3、在appsetting.json配置文件中，添加jwt相关配置信息

  "JWTSetting": {
    "Issuer": "cba",
    "Audience": "cba",
    "SecretKey": "123456789abcdefghi",
    "AccessExpiration": 60,
    "RefreshExpiration": 80
  }

　4、在Startup.cs 中启用Jwt认证

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<JwtSetting>(Configuration.GetSection("JWTSetting"));
    var token = Configuration.GetSection("JWTSetting").Get<JwtSetting>();
    //JWT认证
    services.AddAuthentication(x =>
    {
        x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
    }).AddJwtBearer(x =>
    {
        x.RequireHttpsMetadata = false;
        x.SaveToken = true;
        x.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuerSigningKey = true,
            IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(token.SecretKey)),
            ValidIssuer = token.Issuer,
            ValidAudience = token.Audience,
            ValidateIssuer = false,
            ValidateAudience = false
        };
    });
}

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UseAuthentication();
    app.UseAuthorization();
}

　5、实现认证控制器：

　　a) 添加认证Dto

public class LoginDto
{
    [Required]
    public string Username { get; set; }

    [Required]
    public string Password { get; set; }
}

　　b) 实现用户校验服务：默认实现：当用户密码都等于admin通过校验　　

public interface IUserService
{
    bool IsValid(LoginDto request);
}

public class UserService : IUserService
{
    //本次，固定校验admin
    public bool IsValid(LoginDto request)
    {
        return request.Password == request.Username && request.Username == "admin";
    }
}

　　c) 实现签发token的认证服务：　　

//认证服务接口
public interface IAuthenticateService
{
    bool IsAuthenticated(LoginDto request, out string token);
}

//认证服务
public class TokenAuthenticationService : IAuthenticateService
{
    private readonly IUserService _userService;
    private readonly JwtSetting _jwtSetting;

    public TokenAuthenticationService(IUserService userService, IOptions<JwtSetting> jwtSetting)
    {
        _userService = userService;
        _jwtSetting = jwtSetting.Value;
    }

    public bool IsAuthenticated(LoginDto request, out string token)
    {
        token = string.Empty;
        if (!_userService.IsValid(request))
            return false;
        var claims = new[] { new Claim(ClaimTypes.Name, request.Username) };
        var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_jwtSetting.SecretKey));
        var credentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);
        var jwtToken = new JwtSecurityToken(_jwtSetting.Issuer, _jwtSetting.Audience, claims, expires: DateTime.Now.AddMinutes(_jwtSetting.AccessExpiration), signingCredentials: credentials);
        token = new JwtSecurityTokenHandler().WriteToken(jwtToken);
        return true;
    }
}

　　d) 添加认证控制器

[Route("api/[controller]")]
[ApiController]
public class AuthenticationController : ControllerBase
{
    private IAuthenticateService _authService;

    public AuthenticationController(IAuthenticateService authService)
    {
        _authService = authService;
    }
    [AllowAnonymous]
    [HttpPost, Route("RequestToken")]
    public ActionResult RequestToken([FromBody] LoginDto request)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest("Invalid Request");
        }
        string token;
        if (_authService.IsAuthenticated(request, out token))
        {
            return Ok(token);
        }
        return BadRequest("Invalid Request");
    }
}

　6、注入服务：TokenAuthenticationService 、UserService

services.AddScoped<IUserService, UserService>();
services.AddScoped<IAuthenticateService, TokenAuthenticationService>();

　7、添加测试控制器：

[Authorize]
[Route("api/[controller]")]
[ApiController]
public class AuditLogController : ControllerBase
{
    // GET: api/<AuditLogController>
    [HttpGet]
    public IEnumerable<string> Get()
    {
        return new string[] { "value1", "value2" };
    }
}

　　　到此Jwt认证在.net core中已经实现，接下来验证下运行效果

三、验证结果

　1、请求AuditLog接口：api/AuditLog未传入认证信息时：

　　 ASP.NET Core - JWT认证实现

　2、获取Token:

　　 ASP.NET Core - JWT认证实现

　3、添加token调用接口：

　　 ASP.NET Core - JWT认证实现

四、Swagger UI添加认证

　　在项目中通常都添加了Swagger UI来展示接口及基础测试，那么如果添加了认证后，如何在调用接口前添加认证信息呢？

　　在Startup中：ConfigureServices中添加Swagger设置时，添加认证设置

//注册Swagger生成器，定义一个和多个Swagger 文档
services.AddSwaggerGen(c =>
{
    c.SwaggerDoc("v1", new OpenApiInfo { Title = "AuditLogDemo API", Version = "v1" });
    #region 启用swagger验证功能
    //添加一个必须的全局安全信息，和AddSecurityDefinition方法指定的方案名称一致即可。
    c.AddSecurityRequirement(new OpenApiSecurityRequirement
    {
        {
            new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference {
                    Type = ReferenceType.SecurityScheme,
                    Id = "Bearer"
                }
            },
            new string[] { }
        }
    });
    c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
    {
        Description = "JWT授权(数据将在请求头中进行传输) 在下方输入Bearer {token} 即可，注意两者之间有空格",
        Name = "Authorization",//jwt默认的参数名称
        In = ParameterLocation.Header,//jwt默认存放Authorization信息的位置(请求头中)
        Type = SecuritySchemeType.ApiKey,
        BearerFormat = "JWT",
        Scheme = "Bearer",              
                    
    });
    #endregion
});