如何手动验证 JWT Asp.Net Core？

Question

那里有数以百万计的指南，但似乎没有一个能满足我的需求。我正在创建一个身份验证服务器，它只需要发布和验证/重新发布令牌。所以我不能创建一个中间件类来“验证”cookie 或标头。我只是收到字符串的 POST，我需要以这种方式验证令牌，而不是 .net 核心提供的 Authorize 中间件。

我的初创公司包含我可以开始工作的唯一令牌发行者示例。

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseExceptionHandler("/Home/Error");

            app.UseStaticFiles();
            var secretKey = "mysupersecret_secretkey!123";
            var signingKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(secretKey));

            var options = new TokenProviderOptions
            {

                // The signing key must match!
                Audience = "AllApplications",
                SigningCredentials = new SigningCredentials(signingKey, SecurityAlgorithms.HmacSha256),

                Issuer = "Authentication"
            };
            app.UseMiddleware<TokenProviderMiddleware>(Microsoft.Extensions.Options.Options.Create(options));

我可以在创建时使用中间件，因为我只需要截取用户名和密码的正文。中间件从前面的Startup.cs 代码中获取选项，检查请求路径并从下面看到的上下文中生成令牌。

private async Task GenerateToken(HttpContext context)
{
    CredentialUser usr = new CredentialUser();

    using (var bodyReader = new StreamReader(context.Request.Body))
    {
        string body = await bodyReader.ReadToEndAsync();
        usr = JsonConvert.DeserializeObject<CredentialUser>(body);
    }

    ///get user from Credentials put it in user variable. If null send bad request

    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, JsonConvert.SerializeObject(user)),
        new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
        new Claim(JwtRegisteredClaimNames.Iat, 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);

    ///fill response with jwt
}

上面的这个大块代码将DeserializeCredentialUser json ，然后执行一个返回用户对象的存储过程。然后，我将添加三个声明，然后将其寄回。

我能够成功生成 jwt，并使用 jwt.io 之类的在线工具，我输入了密钥，该工具说它是有效的，并带有一个我可以使用的对象

    {
         "sub": " {User_Object_Here} ",
         "jti": "96914b3b-74e2-4a68-a248-989f7d126bb1",
         "iat": "6/28/2017 4:48:15 PM",
         "nbf": 1498668495,
         "exp": 1498668795,
         "iss": "Authentication",
         "aud": "AllApplications"
    }

我遇到的问题是了解如何根据签名手动检查声明。因为这是一个发布和验证令牌的服务器。像大多数指南一样，设置Authorize 中间件不是一种选择。下面我正在尝试验证令牌。

[Route("api/[controller]")]
public class ValidateController : Controller
{

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Validate(string token)
    {
        var validationParameters = new TokenProviderOptions()
        {
            Audience = "AllMyApplications",
            SigningCredentials = new 
            SigningCredentials("mysupersecret_secretkey!123", 
            SecurityAlgorithms.HmacSha256),

            Issuer = "Authentication"
        };
        var decodedJwt = new JwtSecurityTokenHandler().ReadJwtToken(token);
        var valid = new JwtSecurityTokenHandler().ValidateToken(token, //The problem is here
        /// I need to be able to pass in the .net TokenValidParameters, even though
        /// I have a unique jwt that is TokenProviderOptions. I also don't know how to get my user object out of my claims
    }
}

Answer 1

我stole主要从 ASP.Net Core 源代码中借用了这段代码：https://github.com/aspnet/Security/blob/dev/src/Microsoft.AspNetCore.Authentication.JwtBearer/JwtBearerHandler.cs#L45

根据该代码我创建了这个函数：

private string Authenticate(string token) {
    var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_config["Jwt:Key"]));
    var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);
    List<Exception> validationFailures = null;
    SecurityToken validatedToken;
    var validator = new JwtSecurityTokenHandler();

    // These need to match the values used to generate the token
    TokenValidationParameters validationParameters = new TokenValidationParameters();
    validationParameters.ValidIssuer = "http://localhost:5000";
    validationParameters.ValidAudience = "http://localhost:5000";
    validationParameters.IssuerSigningKey = key;
    validationParameters.ValidateIssuerSigningKey = true;
    validationParameters.ValidateAudience = true;

    if (validator.CanReadToken(token))
    {
        ClaimsPrincipal principal;
        try
        {
            // This line throws if invalid
            principal = validator.ValidateToken(token, validationParameters, out validatedToken);

            // If we got here then the token is valid
            if (principal.HasClaim(c => c.Type == ClaimTypes.Email))
            {
                return principal.Claims.Where(c => c.Type == ClaimTypes.Email).First().Value;
            }
        }
        catch (Exception e)
        {
            _logger.LogError(null, e);
        }
    }

    return String.Empty;
}

validationParameters 需要与您的 GenerateToken 函数中的匹配，然后它应该可以正常验证。