Core Identity Integration Guide

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Overview

http://ASP.NET Core Identity is a membership system that integrates login functionality into your application. It offers features such as user registration, password recovery, and user management. This guide provides a comprehensive overview of how to integrate Identity with JWT authentication in an http://ASP.NET Core application.

Sequence Diagram

Prerequisites

Required NuGet packages:

  • Microsoft.AspNetCore.Identity.EntityFrameworkCore

  • Microsoft.AspNetCore.Authentication.JwtBearer

Step 1: Define User Entity

Create a user entity class that extends IdentityUser:

// AppUser.cs
using Microsoft.AspNetCore.Identity;

namespace Domain
{
    public class AppUser : IdentityUser
    {
        public string DisplayName { get; set; }
        public string Bio { get; set; }
    }
}

Explanation

  • DisplayName: This property is used to store the name that the user wants to display in the application. It can be used for showing the user's name in UI elements instead of their username or email.

  • Bio: This property is used to store a short biography or description about the user. It can be displayed on the user's profile page or any other relevant section of the application.

  • Email and Password: These properties are inherited from the IdentityUser class. The IdentityUser class already includes properties such as Email, UserName, PasswordHash, etc. Email and password configuration is handled by the Identity system during user registration and login.

Step 2: Configure Identity and JWT Services

Create an extension method to configure Identity and JWT services:

// IdentityServiceExtensions.cs
using API.Services;
using Domain;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.IdentityModel.Tokens;
using Persistence;
using System.Text;

namespace API.Extensions
{
    public static class IdentityServiceExtensions
    {
        public static IServiceCollection AddIdentityServices(this IServiceCollection services, IConfiguration config)
        {
            // Configure Identity to use AppUser class and specify password requirements
            services.AddIdentityCore<AppUser>(opt =>
            {
                opt.Password.RequireNonAlphanumeric = false; // Simplified password requirements for this example
            })
            .AddEntityFrameworkStores<DataContext>(); // Use DataContext for storing Identity data

            // Configure JWT authentication
            var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(config["TokenKey"])); // Generate symmetric security key from configuration
            services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                .AddJwtBearer(opt =>
                {
                    opt.TokenValidationParameters = new TokenValidationParameters
                    {
                        ValidateIssuerSigningKey = true,
                        IssuerSigningKey = key,
                        ValidateIssuer = false, // Skip issuer validation for simplicity
                        ValidateAudience = false // Skip audience validation for simplicity
                    };
                });

            services.AddScoped<TokenService>(); // Register TokenService as a scoped service
            return services;
        }
    }
}

Step 3: Setup Database Context

Configure the DataContext to inherit from IdentityDbContext<AppUser>:

// DataContext.cs
using Domain;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

namespace Persistence
{
    public class DataContext : IdentityDbContext<AppUser>
    {
        public DataContext(DbContextOptions options) : base(options)
        {
        }

        public DbSet<Activity> Activities { get; set; } // DbSet for activities
    }
}

Step 4: Configure Services and Middleware

In the Program.cs file, configure the necessary services and middleware:

// Program.cs
using API.Extensions;
using Persistence;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container
builder.Services.AddControllers();
builder.Services.AddApplicationServices(builder.Configuration); // Application-specific services
builder.Services.AddIdentityServices(builder.Configuration); // Identity and JWT services

var app = builder.Build();

// Configure the HTTP request pipeline
app.UseRouting(); // Enable routing
app.UseCors("CorsPolicy"); // Configure CORS policy
app.UseAuthentication(); // Enable authentication middleware
app.UseAuthorization(); // Enable authorization middleware

app.MapControllers(); // Map controllers to endpoints

// Initialize database and seed initial data
using var scope = app.Services.CreateScope();
var services = scope.ServiceProvider;
try
{
    var context = services.GetRequiredService<DataContext>();
    var userManager = services.GetRequiredService<UserManager<AppUser>>();
    await context.Database.MigrateAsync(); // Apply pending migrations
    await Seed.SeedData(context, userManager); // Seed initial data
}
catch (Exception ex)
{
    var logger = services.GetRequiredService<ILogger<Program>>();
    logger.LogError(ex, "An error occurred during migration");
}

app.Run();

Step 5: Implement Token Service

Create a service to generate JWT tokens:

// TokenService.cs
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;
using Domain;
using Microsoft.IdentityModel.Tokens;

namespace API.Services
{
    public class TokenService
    {
        private readonly IConfiguration _config;

        public TokenService(IConfiguration config)
        {
            _config = config;
        }

        // Method to create JWT token for a user
        public string CreateToken(AppUser user)
        {
            // Define claims to be included in the token
            var claims = new List<Claim>
            {
                new Claim(ClaimTypes.Name, user.UserName), // User name claim
                new Claim(ClaimTypes.NameIdentifier, user.Id), // User ID claim
                new Claim(ClaimTypes.Email, user.Email) // Email claim
            };

            // Generate symmetric security key from configuration
            var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_config["TokenKey"]));
            var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha512Signature); // Generate signing credentials

            // Define token descriptor
            var tokenDescriptor = new SecurityTokenDescriptor
            {
                Subject = new ClaimsIdentity(claims), // Set claims
                Expires = DateTime.UtcNow.AddDays(7), // Token expiration (7 days)
                SigningCredentials = creds // Set signing credentials
            };

            var tokenHandler = new JwtSecurityTokenHandler();
            var token = tokenHandler.CreateToken(tokenDescriptor); // Create token
            return tokenHandler.WriteToken(token); // Return token as string
        }
    }
}

Step 6: Implement Account Controller

Create a controller to handle user registration and login:

// AccountController.cs
using API.DTOs;
using API.Services;
using Domain;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;

namespace API.Controllers
{
    public class AccountController : BaseApiController
    {
        private readonly UserManager<AppUser> _userManager;
        private readonly SignInManager<AppUser> _signInManager;
        private readonly TokenService _tokenService;

        public AccountController(UserManager<AppUser> userManager, SignInManager<AppUser> signInManager, TokenService tokenService)
        {
            _userManager = userManager;
            _signInManager = signInManager;
            _tokenService = tokenService;
        }

        // Login action
        [HttpPost("login")]
        public async Task<ActionResult<UserDto>> Login(LoginDto loginDto)
        {
            var user = await _userManager.FindByEmailAsync(loginDto.Email); // Find user by email
            if (user == null) return Unauthorized("Invalid email"); // Return unauthorized if user not found

            var result = await _userManager.CheckPasswordAsync(user, loginDto.Password); // Check user password
            if (!result) return Unauthorized("Invalid password"); // Return unauthorized if password is incorrect

            // Return user details and token
            return new UserDto
            {
                DisplayName = user.DisplayName,
                Token = _tokenService.CreateToken(user), // Generate JWT token
                Username = user.UserName
            };
        }

        // Registration action
        [HttpPost("register")]
        public async Task<ActionResult<UserDto>> Register(RegisterDto registerDto)
        {
            // Check if email is already taken
            if (await _userManager.Users.AnyAsync(x => x.Email == registerDto.Email))
            {
                return BadRequest("Email already taken");
            }

            // Check if username is already taken
            if (await _userManager.Users.AnyAsync(x => x.UserName == registerDto.Username))
            {
                return BadRequest("Username already taken");
            }

            var user = new AppUser
            {
                DisplayName = registerDto.DisplayName,
                Email = registerDto.Email,
                UserName = registerDto.Username
            };

            var result = await _userManager.CreateAsync(user, registerDto.Password); // Create new user

            if (!result.Succeeded) return BadRequest(result.Errors); // Return errors if user creation failed

            // Return user details and token
            return new UserDto
            {
                DisplayName = user.DisplayName,
                Token = _tokenService.CreateToken(user), // Generate JWT token
                Username = user.UserName
            };
        }
    }
}

Flow of Identity Integration

  1. Application Startup:

    • The Program.cs file is the entry point of the application.

    • The necessary services, including Identity and JWT authentication, are configured using the AddIdentityServices extension method.

    • The DataContext is set up to use Identity and connect to the database

.

  • Authentication and authorization middleware are added to the HTTP request pipeline.

  1. User Registration:

    • The user sends a POST request to the registration endpoint with their details.

    • The AccountController handles the registration request.

    • If the provided email and username are available, a new AppUser is created using UserManager.

    • The user is saved to the database, and a JWT token is generated using TokenService.

    • The token and user details are returned in the response.

  2. User Login:

    • The user sends a POST request to the /api/account/login endpoint with their email and password.

    • The AccountController receives the request and calls the Login action.

    • Inside the Login action:

      • The UserManager is used to find the user by email.

      • If the user is not found, an "Invalid email" response is returned.

      • If the user is found, the password is checked using UserManager.

      • If the password is invalid, an "Invalid password" response is returned.

      • If the email and password are valid, the TokenService is called to generate a JWT token.

      • The generated token and user details are returned in the response.

  3. Authenticated Requests:

    • For subsequent requests to protected endpoints, the client includes the JWT token in the Authorization header.

    • The Authentication middleware intercepts the request and validates the token.

    • If the token is valid, the user is considered authenticated, and the request proceeds to the corresponding controller action.

    • If the token is invalid or not present, an Unauthorized response is returned.

  4. Authorization:

    • The Authorization middleware checks if the authenticated user has the necessary permissions to access the requested resource.

    • Authorization policies can be defined using attributes such as [Authorize] on controllers or actions.

    • If the user meets the authorization requirements, the request is allowed to proceed.

    • If the user does not have the required permissions, a Forbidden response is returned.

Considerations

  1. Password Hashing:

    • http://ASP.NET Core Identity uses secure password hashing by default.

    • Passwords are hashed using the PBKDF2 algorithm with a configurable number of iterations.

    • Salt is generated individually for each password to prevent rainbow table attacks.

  2. Email Confirmation and Password Reset:

    • Consider implementing email confirmation to verify user email addresses.

    • Provide a password reset functionality to allow users to reset their passwords securely.

    • Use secure token generation and expiration for email confirmation and password reset links.

  3. Account Lockout:

    • Implement account lockout to prevent brute-force attacks.

    • Configure the maximum number of failed login attempts and lockout duration.

    • Provide a mechanism for users to unlock their accounts (e.g., via email or admin intervention).

  4. Role-Based Authorization:

    • Assign roles to users to control access to specific resources or actions.

    • Use the [Authorize(Roles = "...")] attribute to restrict access based on user roles.

    • Manage user roles using RoleManager<IdentityRole>.

  5. Token Expiration and Refresh Tokens:

    • Set an appropriate expiration time for JWT tokens to limit their validity.

    • Implement refresh tokens to allow users to obtain new access tokens without re-authenticating.

    • Securely store and validate refresh tokens on the server-side.

  6. Secure Communication:

    • Use HTTPS to encrypt all communication between the client and the server.

    • Ensure that sensitive data, such as passwords and tokens, are transmitted securely.


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