ASP.NET Core Identity Basics
💡 Concept Name
ASP.NET Core Identity
📘 Quick Intro
ASP.NET Core Identity is a full-featured authentication and user management system. It simplifies user registration, login, password storage, and role-based access. It's built on Entity Framework Core and integrates tightly with ASP.NET Core apps.
🧠 Analogy / Short Story
Think of Identity like the receptionist in a secure office building. It manages the employee records (users), verifies their ID on entry (login), and grants access to rooms based on roles. It also keeps a logbook (claims) and ensures your badge (password) is secure and encrypted.
🔧 Technical Explanation
Identity provides a `UserManager`, `SignInManager`, and `RoleManager` to manage authentication and authorization. Users are stored in a database via Entity Framework Core. It also supports token generation, email confirmation, and 2FA. You can scaffold Identity UI or customize views using Razor Pages.
🎯 Purpose & Use Case
- ✅ Enable user registration and login securely
- ✅ Store hashed passwords and manage user roles
- ✅ Support external login providers (Google, Facebook, etc.)
- ✅ Enable account lockout, 2FA, and email confirmation
- ✅ Secure web apps with built-in authorization and claims
💻 Real Code Example
// Add Identity in Program.cs
builder.Services.AddIdentity<IdentityUser, IdentityRole>()
.AddEntityFrameworkStores<ApplicationDbContext>()
.AddDefaultTokenProviders();
// Protect route with Identity
[Authorize]
public class ProfileController : Controller
{
public IActionResult Index() => View();
}
❓ Interview Q&A
Q1: What is ASP.NET Core Identity?
A: A built-in system for user authentication, registration, and role management.
Q2: What are the key services in Identity?
A: `UserManager`, `SignInManager`, `RoleManager`.
Q3: Where are users stored?
A: In the database using Entity Framework Core.
Q4: How are passwords stored?
A: Hashed using secure algorithms like PBKDF2.
Q5: What is the purpose of claims?
A: Claims hold additional user data like department or country.
Q6: Can Identity be used in Razor Pages?
A: Yes, it fully supports Razor Pages.
Q7: How to add external login support?
A: Use services like `.AddGoogle()`, `.AddFacebook()` in Program.cs.
Q8: What is `AddDefaultTokenProviders()` for?
A: It enables email confirmation, password reset, etc.
Q9: Can we customize Identity UI?
A: Yes, by scaffolding Identity pages.
Q10: What are roles used for?
A: To control access by grouping users based on permissions.
📝 MCQs
📝 MCQs
Q1. Which service handles login logic in Identity?
- UserService
- IdentityCore
- SignInManager
- LoginHandler
Q2. What is stored in the AspNetUsers table?
- Sessions
- Role claims
- User accounts
- Controllers
Q3. How are passwords stored?
- Plain text
- Base64
- Hashed
- Encrypted
Q4. Which class assigns roles to users?
- UserManager
- ClaimsHandler
- RoleManager
- TokenProvider
Q5. Which method adds Identity in Program.cs?
- ConfigureIdentity
- AddIdentity
- UseIdentity
- EnableLogin
Q6. What attribute protects a controller using Identity?
- [Identity]
- [Secure]
- [Authorize]
- [Protected]
Q7. Which provider allows email confirmation?
- MailKit
- SMTP
- DefaultTokenProviders
- GoogleToken
Q8. Can Identity work without a database?
- Yes
- No
- Only in-memory
- Only with NoSQL
Q9. Which table holds roles?
- UserRoles
- RoleTable
- AspNetRoles
- RoleClaims
Q10. What does SignInManager.PasswordSignInAsync do?
- Logs out user
- Creates user
- Logs in a user
- Resets password
💡 Bonus Insight
ASP.NET Core Identity is customizable — you can use your own user class, database schema, or even swap out EF Core. It's secure by default but also extensible for advanced scenarios like claims transformation and policy-based access control.
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