ASP.NET OWIN 是否可以设置为以 random/occasional 间隔向用户询问 2FA 代码?

Can ASP.NET OWIN be set to challenge users for a 2FA code at random/occasional intervals?

我想将我的 MVC 应用程序配置为随机质询用户,对网站的 1 比 N 访问进行 2 因素身份验证检查。

首先,我只是在登录过程中这样做:

int challengeFrequency = Convert.ToInt16(ConfigurationManager.AppSettings["ChallengeFrequency"]);
var result = await SignInManager.PasswordSignInAsync(model.Email, model.Password, model.RememberMe, shouldLockout: true);
switch (result)
{
    case SignInStatus.Success:
        Random rnd = new Random();
        if(rnd.Next(challengeFrequency) == 1)
        {
            if (!await SignInManager.SendTwoFactorCodeAsync("Phone Code"))
            {
                return RedirectToAction("Error");
            }
            return RedirectToAction("VerifyCode", new { Provider = "Phone Code", ReturnUrl = returnUrl, RememberMe = model.RememberMe });
        }
        return RedirectToLocal(returnUrl);
    // other cases
}

但事实证明我误解了该过程,如果用户拥有站点的有效 cookie,则不会调用 PasswordSignInAsync。我打算更改这些设置,以便用户在任何情况下每次都必须登录,所以在 Startup.Auth 中我添加了:

app.UseCookieAuthentication(new CookieAuthenticationOptions
{
    AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
    LoginPath = new PathString("/Account/Login"),
    SlidingExpiration = true,
    ExpireTimeSpan = TimeSpan.FromSeconds(5),
    Provider = new CookieAuthenticationProvider
    {
        OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<ApplicationUserManager, ApplicationUser>(
            validateInterval: TimeSpan.FromSeconds(0), 
            regenerateIdentity: (manager, user) => user.GenerateUserIdentityAsync(manager))
    }
});

所以现在用户每次都会受到挑战。但是,当然,如果没有 cookie,我们永远不会得到 SignInStatus.Success 结果,用户总是会被要求输入密码和 2FA 代码。

如何中断该过程以确保用户始终必须使用密码登录,但只是偶尔被要求输入 2FA 代码?

我最终能够通过即时生成令牌并使用它来实现 TwoFactorSignIn 方法来实现这一点,如下所示:

int challengeFrequency = Convert.ToInt16(ConfigurationManager.AppSettings["ChallengeFrequency"]);
var result = await SignInManager.PasswordSignInAsync(model.Email, model.Password, model.RememberMe, shouldLockout: true);
switch (result)
{
    case SignInStatus.Success:
        return RedirectToLocal(returnUrl);
    case SignInStatus.RequiresVerification:
        Random rnd = new Random();
        if (rnd.Next(1, challengeFrequency) == 1)
        {
            if (!await SignInManager.SendTwoFactorCodeAsync("Phone Code"))
            {
                return RedirectToAction("Login", "Account");
            }

            return RedirectToAction("VerifyCode", new { Provider = "Phone Code", ReturnUrl = returnUrl, RememberMe = model.RememberMe });
        }
        else
        {
            var token = await UserManager.GenerateTwoFactorTokenAsync(user.Id, "Phone Code");
            await SignInManager.TwoFactorSignInAsync("Phone Code", token, false, false);
            return RedirectToLocal(returnUrl);
        }
    // other cases
}