在 ASP.NET Core 3 中使用 id_token

Question

在 ASP.NET Core 3 应用程序中，我需要处理来自 id_token 和 access_token 的信息。

id_token 有会员信息，有时需要这些信息来制定政策。由于成员信息可能很大，将其作为access_token 的一部分是不可能的（令牌超过允许的最大大小）。

客户在x-id-token 标头中发送id_token，我正在寻找一种方法来提取它并使用其中的声明。

现在我已经配置了 JwtBearer 身份验证，它可以与 Authorization: Bearer access_token 标头无缝协作。

public void ConfigureServices(IServiceCollection services) {
      services.AddAuthentication(options =>
      {
        options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
      })
      .AddJwtBearer(options =>
      {
        options.Authority = $"https://{Configuration["auth:Domain"]}/";
        options.Audience = Configuration["auth:Audience"];
      });
...
}

Answer 1

正如问题中所述，我需要在授权流程中执行一个步骤来验证自定义标头中提供的 id_token 和 membership_id。我最终以以下形式创建了一个自定义身份验证要求处理程序

  internal class MembershipRequirement : AuthorizationHandler<MembershipRequirement>, IAuthorizationRequirement
  {
    public MembershipRequirement(IConfiguration configuration)
    {
      Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, MembershipRequirement requirement)
    {
      var authFilterCtx = (Microsoft.AspNetCore.Mvc.Filters.AuthorizationFilterContext)context.Resource;
      string idToken = authFilterCtx.HttpContext.Request.Headers["x-id-token"];
      string membershipId = authFilterCtx.HttpContext.Request.Headers["x-selected-membership-id"];

      if (idToken != null && membershipId != null)
      {
        var identity = ValidateIdToken(idToken).Result;

        if (identity != null)
        {
          var subscriptions = identity.Claims.ToList().FindAll(s => s.Type == "https://example.com/subs").ToList();
          var assignments = subscriptions.Select(s => JsonSerializer.Deserialize<Subscription>(s.Value)).ToList();

          var membership = assignments.Find(a => a.id == membershipId);

          if (membership != null)
          {
            // assign the id token claims to user identity
            context.User.AddIdentity(new ClaimsIdentity(identity.Claims));

            context.Succeed(requirement);
          }
          else { context.Fail(); }
        }
        else
        {
          context.Fail();
        }
      }

      return Task.FromResult<object>(null);
    }

    private async Task<ClaimsPrincipal> ValidateIdToken(string token)
    {
      try
      {
        IConfigurationManager<OpenIdConnectConfiguration> configurationManager = new ConfigurationManager<OpenIdConnectConfiguration>($"https://{Configuration["Auth:Domain"]}/.well-known/openid-configuration", new OpenIdConnectConfigurationRetriever());
        OpenIdConnectConfiguration openIdConfig = await configurationManager.GetConfigurationAsync(CancellationToken.None);

        TokenValidationParameters validationParameters =
                      new TokenValidationParameters
                      {
                        IssuerSigningKeys = openIdConfig.SigningKeys,
                        ValidateIssuer = false,
                        ValidateAudience = false
                      };

        var validator = new JwtSecurityTokenHandler();
        SecurityToken validatedToken;
        var identity = validator.ValidateToken(token, validationParameters, out validatedToken);

        return identity;

      }
      catch (Exception e)
      {
        Console.Writeline($"Error occurred while validating token: {e.Message}");
        return null;
      }
    }
  }

  internal class Subscription
  {
    public string name { get; set; }
    public string id { get; set; }
  }

然后在public void ConfigureServices(IServiceCollection services) 方法中添加了一个策略来检查id_token 中的成员身份

      services.AddAuthorization(options =>
      {
        options.AddPolicy("RequiredCompanyMembership", policy => policy.Requirements.Add(new MembershipRequirement(Configuration)));
      });

对我们而言，此政策适用于所有授权端点。