在ASP.NET Core中，使用Identity框架来实现基本的登录系统是非常简单的，但可能会给初学者带来一些困扰。以下是一个简单的解决方案，包含代码示例：

1. 创建ASP.NET Core Web应用程序项目。
2. 在Startup.cs文件中，添加对Identity的服务配置：

using Microsoft.AspNetCore.Identity;

public void ConfigureServices(IServiceCollection services)
{
    // 添加Identity服务
    services.AddIdentity()
        .AddDefaultTokenProviders()
        .AddEntityFrameworkStores();
        
    // 其他配置...
}

3. 创建一个名为ApplicationDbContext的类，继承自IdentityDbContext：

using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

public class ApplicationDbContext : IdentityDbContext
{
    public ApplicationDbContext(DbContextOptions options)
        : base(options)
    {
    }
}

4. 在Configure方法中启用Identity中间件：

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    // 其他配置...

    // 启用Identity中间件
    app.UseAuthentication();

    // 其他配置...
}

5. 创建一个名为AccountController的控制器，包含登录和注册的动作方法：

using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;

public class AccountController : Controller
{
    private readonly SignInManager _signInManager;
    private readonly UserManager _userManager;

    public AccountController(
        SignInManager signInManager,
        UserManager userManager
    )
    {
        _signInManager = signInManager;
        _userManager = userManager;
    }

    [HttpGet]
    public IActionResult Login()
    {
        return View();
    }

    [HttpPost]
    public async Task Login(LoginViewModel model)
    {
        if (ModelState.IsValid)
        {
            var result = await _signInManager.PasswordSignInAsync(model.Email, model.Password, model.RememberMe, false);
            
            if (result.Succeeded)
            {
                return RedirectToAction("Index", "Home");
            }
            else
            {
                ModelState.AddModelError("", "无效的登录尝试.");
            }
        }

        return View(model);
    }

    [HttpGet]
    public IActionResult Register()
    {
        return View();
    }

    [HttpPost]
    public async Task Register(RegisterViewModel model)
    {
        if (ModelState.IsValid)
        {
            var user = new IdentityUser { UserName = model.Email, Email = model.Email };
            var result = await _userManager.CreateAsync(user, model.Password);
            
            if (result.Succeeded)
            {
                await _signInManager.SignInAsync(user, isPersistent: false);
                return RedirectToAction("Index", "Home");
            }
            else
            {
                foreach (var error in result.Errors)
                {
                    ModelState.AddModelError("", error.Description);
                }
            }
        }

        return View(model);
    }
}

6. 创建LoginViewModel和RegisterViewModel类，用于在视图中接收登录和注册表单的输入：

public class LoginViewModel
{
    [Required]
    [EmailAddress]
    public string Email { get; set; }

    [Required]
    [DataType(DataType.Password)]
    public string Password { get; set; }

    [Display(Name = "记住我")]
    public bool RememberMe { get; set; }
}

public class RegisterViewModel
{
    [Required]
    [EmailAddress]
    public string Email { get; set; }

    [Required]
    [DataType(DataType.Password)]
    public string Password { get; set; }

    [DataType(DataType.Password)]
    [Compare("Password", ErrorMessage = "密码和确认密码不匹配.")]
    [Display(Name = "确认密码")]
    public string ConfirmPassword { get; set; }
}

7. 创建登录和注册的视图文件（Login.cshtml和Register.cshtml），并使用视图模型来呈现表单和接收用户输入。

这样，你就可以通过访问Account/Login和Account/Register来访问登录和注册页面，并通过输入合法的用户凭据来登录和注册用户。