1. 在ASP.NET Core Identity中启用双因素身份验证。

在Startup.cs文件中，使用AddIdentity方法来添加身份验证服务，并将UseTwoFactorSignIn设置为true。

services.AddIdentity(options =>
{
  options.SignIn.RequireConfirmedAccount = true;
  options.SignIn.RequireConfirmedEmail = true;
})
  .AddEntityFrameworkStores()
  .AddDefaultTokenProviders()
  .AddDefaultUI()
  .AddTokenProvider>("twoFactor")
  .AddTokenProvider>("email");

services.Configure("twoFactor", options =>
{
  options.TokenLifespan = TimeSpan.FromMinutes(5);
});

services.Configure("email", options =>
{
  options.TokenLifespan = TimeSpan.FromDays(30);
});

services.Configure(options =>
{
  options.ValidationInterval = TimeSpan.FromMinutes(10);
});

services.ConfigureApplicationCookie(options =>
{
  options.LoginPath = "/Account/Login";
  options.LogoutPath = "/Account/Logout";
  options.AccessDeniedPath = "/Account/AccessDenied";
});
    
services.AddAuthentication()
  .AddGoogle(options =>
  {
    options.ClientId = Configuration["Authentication:Google:ClientId"];
    options.ClientSecret = Configuration["Authentication:Google:ClientSecret"];
  });
  
services.Configure(options =>
{
  options.DefaultAuthenticateScheme = IdentityConstants.ApplicationScheme;
  options.DefaultForbidScheme = IdentityConstants.ApplicationScheme;
  options.DefaultChallengeScheme = IdentityConstants.ExternalScheme;
});
  
services.Configure(options =>
{
  options.DefaultSignInScheme = IdentityConstants.ApplicationScheme;
  options.DefaultAuthenticateScheme = IdentityConstants.TwoFactorUserIdScheme;
  options.DefaultChallengeScheme = IdentityConstants.TwoFactorUserIdScheme;
  options.DefaultScheme = IdentityConstants.ApplicationScheme;
});

2. 实现双因素身份验证

在ASP.NET Core Identity中，使用多个身份验证方案来实现双因素身份验证。在Startup.cs文件中，可以看到如何配置身份验证选项来指定默认身份验证方案和处理多个身份验证方