/// <summary>
  /// 公钥：AppKey
  /// 私钥：AppSecret
  /// 会话：SessionKey
  /// </summary>
  public class PassportController : Controller
  {
    private readonly IAppInfoService _appInfoService = new AppInfoService();
    private readonly IAppUserService _appUserService = new AppUserService();
    private readonly IUserAuthSessionService _authSessionService = new UserAuthSessionService();
    private readonly IUserAuthOperateService _userAuthOperateService = new UserAuthOperateService();

    private const string AppInfo = "AppInfo";
    private const string SessionKey = "SessionKey";
    private const string SessionUserName = "SessionUserName";

    //默认登录界面
    public ActionResult Index(string appKey = "", string username = "")
    {
      TempData[AppInfo] = _appInfoService.Get(appKey);

      var viewModel = new PassportLoginRequest
      {
        AppKey = appKey,
        UserName = username
      };

      return View(viewModel);
    }

    //授权登录
    [HttpPost]
    public ActionResult Index(PassportLoginRequest model)
    {
      //获取应用信息
      var appInfo = _appInfoService.Get(model.AppKey);
      if (appInfo == null)
      {
        //应用不存在
        return View(model);
      }

      TempData[AppInfo] = appInfo;

      if (ModelState.IsValid == false)
      {
        //实体验证失败
        return View(model);
      }

      //过滤字段无效字符
      model.Trim();

      //获取用户信息
      var userInfo = _appUserService.Get(model.UserName);
      if (userInfo == null)
      {
        //用户不存在
        return View(model);
      }

      if (userInfo.UserPwd != model.Password.ToMd5())
      {
        //密码不正确
        return View(model);
      }

      //获取当前未到期的Session
      var currentSession = _authSessionService.ExistsByValid(appInfo.AppKey, userInfo.UserName);
      if (currentSession == null)
      {
        //构建Session
        currentSession = new UserAuthSession
        {
          AppKey = appInfo.AppKey,
          CreateTime = DateTime.Now,
          InvalidTime = DateTime.Now.AddYears(1),
          IpAddress = Request.UserHostAddress,
          SessionKey = Guid.NewGuid().ToString().ToMd5(),
          UserName = userInfo.UserName
        };

        //创建Session
        _authSessionService.Create(currentSession);
      }
      else
      {
        //延长有效期，默认一年
        _authSessionService.ExtendValid(currentSession.SessionKey);
      }

      //记录用户授权日志
      _userAuthOperateService.Create(new UserAuthOperate
      {
        CreateTime = DateTime.Now,
        IpAddress = Request.UserHostAddress,
        Remark = string.Format("{0} 登录 {1} 授权成功", currentSession.UserName, appInfo.Title),
        SessionKey = currentSession.SessionKey
      }); 104 
      var redirectUrl = string.Format("{0}?SessionKey={1}&SessionUserName={2}",
        appInfo.ReturnUrl, 
        currentSession.SessionKey, 
        userInfo.UserName);

      //跳转默认回调页面
      return Redirect(redirectUrl);
    }
  }
Memcached会话标识验证核心代码：
public class PassportController : ApiController
  {
    private readonly IUserAuthSessionService _authSessionService = new UserAuthSessionService();
    private readonly IUserAuthOperateService _userAuthOperateService = new UserAuthOperateService();

    public bool Get(string sessionKey = "", string remark = "")
    {
      if (_authSessionService.GetCache(sessionKey))
      {
        _userAuthOperateService.Create(new UserAuthOperate
        {
          CreateTime = DateTime.Now,
          IpAddress = Request.RequestUri.Host,
          Remark = string.Format("验证成功-{0}", remark),
          SessionKey = sessionKey
        });

        return true;
      }

      _userAuthOperateService.Create(new UserAuthOperate
      {
        CreateTime = DateTime.Now,
        IpAddress = Request.RequestUri.Host,
        Remark = string.Format("验证失败-{0}", remark),
        SessionKey = sessionKey
      });

      return false;
    }
  }

public class SSOAuthAttribute : ActionFilterAttribute
  {
    public const string SessionKey = "SessionKey";
    public const string SessionUserName = "SessionUserName";

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
      var cookieSessionkey = "";
      var cookieSessionUserName = "";

      //SessionKey by QueryString
      if (filterContext.HttpContext.Request.QueryString[SessionKey] != null)
      {
        cookieSessionkey = filterContext.HttpContext.Request.QueryString[SessionKey];
        filterContext.HttpContext.Response.Cookies.Add(new HttpCookie(SessionKey, cookieSessionkey));
      }

      //SessionUserName by QueryString
      if (filterContext.HttpContext.Request.QueryString[SessionUserName] != null)
      {
        cookieSessionUserName = filterContext.HttpContext.Request.QueryString[SessionUserName];
        filterContext.HttpContext.Response.Cookies.Add(new HttpCookie(SessionUserName, cookieSessionUserName));
      }

      //从Cookie读取SessionKey
      if (filterContext.HttpContext.Request.Cookies[SessionKey] != null)
      {
        cookieSessionkey = filterContext.HttpContext.Request.Cookies[SessionKey].Value;
      }

      //从Cookie读取SessionUserName
      if (filterContext.HttpContext.Request.Cookies[SessionUserName] != null)
      {
        cookieSessionUserName = filterContext.HttpContext.Request.Cookies[SessionUserName].Value;
      }

      if (string.IsNullOrEmpty(cookieSessionkey) || string.IsNullOrEmpty(cookieSessionUserName))
      {
        //直接登录
        filterContext.Result = SsoLoginResult(cookieSessionUserName);
      }
      else
      {
        //验证
        if (CheckLogin(cookieSessionkey, filterContext.HttpContext.Request.RawUrl) == false)
        {
          //会话丢失，跳转到登录页面
          filterContext.Result = SsoLoginResult(cookieSessionUserName);
        }
      }

      base.OnActionExecuting(filterContext);
    }

    public static bool CheckLogin(string sessionKey, string remark = "")
    {
      var httpClient = new HttpClient
      {
        BaseAddress = new Uri(ConfigurationManager.AppSettings["SSOPassport"])
      };

      var requestUri = string.Format("api/Passport?sessionKey={0}&remark={1}", sessionKey, remark);

      try
      {
        var resp = httpClient.GetAsync(requestUri).Result;

        resp.EnsureSuccessStatusCode();

        return resp.Content.ReadAsAsync<bool>().Result;
      }
      catch (Exception ex)
      {
        throw ex;
      }
    }

    private static ActionResult SsoLoginResult(string username)
    {
      return new RedirectResult(string.Format("{0}/passport?appkey={1}&username={2}",
          ConfigurationManager.AppSettings["SSOPassport"],
          ConfigurationManager.AppSettings["SSOAppKey"],
          username));
    }
  }

[SSOAuth]
  public class HomeController : Controller
  {
    public ActionResult Index()
    {
      return View();
    }

    public ActionResult About()
    {
      ViewBag.Message = "Your application description page.";

      return View();
    }

    public ActionResult Contact()
    {
      ViewBag.Message = "Your contact page.";

      return View();
    }
  }