Step by Step: Implementing Authentication with Identity

Introduction

Imagine you have a building and need to ensure that only authorized people can enter. You hire an electronic doorman to verify users' identities at the entrance. ASP.NET Core Identity works similarly, acting as this electronic doorman that controls access to your application.

In today’s post, we’ll create a practical tutorial on how to set up and use ASP.NET Core Identity for authentication.

What is ASP.NET Core Identity?

ASP.NET Core Identity is a library that simplifies the implementation of authentication and authorization in .NET applications. It provides ready-to-use functionalities to manage users, passwords, roles, and claims.

Step-by-Step Guide to Set Up ASP.NET Core Identity

Step 1: Add NuGet Packages

First, add the necessary packages to your project:

dotnet add package Microsoft.AspNetCore.Identity.EntityFrameworkCore
dotnet add package Microsoft.EntityFrameworkCore.SqlServer

Step 2: Configure DbContext and Identity

Create an ApplicationDbContext class that inherits from IdentityDbContext:

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

In the Startup.cs file, configure the Identity service:

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApplicationDbContext>(options =>
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddIdentity<IdentityUser, IdentityRole>()
        .AddEntityFrameworkStores<ApplicationDbContext>()
        .AddDefaultTokenProviders();

    services.AddControllersWithViews();
}

Step 3: Configure Authentication Middleware

In the Configure method of Startup.cs, add the authentication and authorization middlewares:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }
    else
    {
        app.UseExceptionHandler("/Home/Error");
        app.UseHsts();
    }

    app.UseHttpsRedirection();
    app.UseStaticFiles();

    app.UseRouting();

    app.UseAuthentication();
    app.UseAuthorization();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllerRoute(
            name: "default",
            pattern: "{controller=Home}/{action=Index}/{id?}");
        endpoints.MapRazorPages();
    });
}

Step 4: Create Registration and Login Pages

Create controllers and views to allow users to register, log in, and log out. ASP.NET Core Identity provides scaffolding to make this task easier:

dotnet aspnet-codegenerator identity -dc ApplicationDbContext

This will create the basic authentication pages for your application.

Conclusion

ASP.NET Core Identity is like an electronic doorman that verifies users' identities, ensuring that only authorized people have access to your application. By following these steps, you can implement authentication efficiently and securely in your .NET applications.