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Part-2 Blazor Server Cookie Authentication


In this article, we are going to implement User Registration logic in the Blazor Server application.

In this part of the article, we have to accomplish our targets like:
  • User Registration Form.
  • Password Hashing
  • User Registration Logic.
Click here for part-1

Create Asp.Net Core Areas Folder:

We are going to create Razor Pages for our User Registration, so let store them in the 'Areas' folder. So let's create 'Areas' folders and also add the 'Layout' template and a few other additional configurations.

Now let's create folders into our application like 'Areas\Identity\Pages\Account', 'Areas\Identity\Pages\Shared'.

Let's create a new layout for the pages inside of the 'Areas' folder. Let's create the layout file '_Layout.cshtml'.
Areas/Identity/Pages/Shared/_Layout.cshtml:
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="/css/bootstrap/bootstrap.min.css" />
</head>
<body>
    <nav class="navbar navbar-dark bg-primary">
        <div class="container-fluid">
            <span class="navbar-brand mb-0 h1">Navbar</span>
        </div>
    </nav>
    @RenderBody()
</body>
</html>
Let's create a new '_ViewImports.cshtml' file into the 'Areas' to register the razor tag helper and then to register the namespaces.
Areas/Identity/Pages/_ViewImports.cshtml:
  
@using Dot6.Bserver.Cookie.Auth.Areas.Identity.Pages.Account
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
Let's create a new '_ViewStart.cshtml' file into the 'Areas' in which will specify the path to our newly created layout.
Areas/Identity/Pages/_ViewStart.cshtml:
@{
    Layout = "/Areas/Identity/Pages/Shared/_Layout.cshtml";
}

Create Registration From Model:

Now let's create a model for form binding like 'Models/Auth/RegiserVm.cs'.
Models/Auth/RegisterVm.cs:
namespace Dot6.Bserver.Cookie.Auth.Models.Auth;
public class RegisterVm
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }
    public string Password { get; set; }
    public string ConfirmPassword { get; set; }
}

Implement User Registration Logic:

Let's implement 'User Registration' logic, so lets create files like 'AccountLogic', 'IAccountLogic'.
Logic/IAccountLogic.cs:
public interface IAccountLogic
{
}
Logic/AccountLogic.cs:
using Dot6.Bserver.Cookie.Auth.Data;

namespace Dot6.Bserver.Cookie.Auth.Logic;

public class AccountLogic : IAccountLogic
{
    private readonly MyCookieAuthContext _myCookieAuthContext;
    private readonly IHttpContextAccessor _accessor;

    public AccountLogic(MyCookieAuthContext myCookieAuthContext,
    IHttpContextAccessor accessor)
    {
        _myCookieAuthContext = myCookieAuthContext;
        _accessor = accessor;
    }
}
  • Here injected 'MyCookieAuthContext' and 'IHttpContextAcessor'.
Register our  'IHttpContextAccessor','IAccountLogic', 'AccountLogic' into the 'Program.cs'.
Program.cs:
builder.Services.AddScoped<IAccountLogic, AccountLogic>();
builder.Services.AddHttpContextAccessor();
Let's add logic for validating our user registration model.
using System.Text.RegularExpressions;

private string ResigstrationValidations(RegisterVm registerVm)
{
	if (string.IsNullOrEmpty(registerVm.Email))
	{
		return "Eamil can't be empty";
	}

	string emailRules = @"[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?";
	if (!Regex.IsMatch(registerVm.Email, emailRules))
	{
		return "Not a valid email";
	}

	if (_myCookieAuthContext.Users.Any(_ => _.Email.ToLower() == registerVm.Email.ToLower()))
	{
		return "user already exists";
	}

	if (string.IsNullOrEmpty(registerVm.Password)
		|| string.IsNullOrEmpty(registerVm.ConfirmPassword))
	{
		return "Password Or ConfirmPasswor Can't be empty";
	}

	if (registerVm.Password != registerVm.ConfirmPassword)
	{
		return "Invalid confirm password";
	}

	// atleast one lower case letter
	// atleast one upper case letter
	// atleast one special character
	// atleast one number
	// atleast 8 character length
	string passwordRules = @"^.*(?=.{8,})(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[!*@#$%^&+=]).*$";
	if (!Regex.IsMatch(registerVm.Password, passwordRules))
	{
		return "Not a valid password";
	}
	return string.Empty;
}
  • (Line: 5-8) Checking user email address empty or not.
  • (Line: 10-14) Email validation pattern check.
  • (Line: 16-19) Checking email against the database to confirm the user is already registered or not.
  • (Line: 21-25) Checking 'Password' or 'ConfirmPassword' empty or not.
  • (Line: 27-30) Verifying the 'Password' and 'ConfirmPassword' matching or not.
  • (Line: 32-41) Password validation pattern check.
Password is a security key for user authentication. It is a basic rule that never stores the plain password into the tables directly. So always recommend applying hashing on passwords. Hashing means oneway encryption which means value can't be decrypted. So let's add our password hashing logic.
Logic/AccountLogic.cs:
private string PasswordHash(string password)
{
	byte[] salt = new byte[16];
	new RNGCryptoServiceProvider().GetBytes(salt);

	var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 1000);
	byte[] hash = pbkdf2.GetBytes(20);

	byte[] hashBytes = new byte[36];
	Array.Copy(salt, 0, hashBytes, 0, 16);
	Array.Copy(hash, 0, hashBytes, 16, 20);

	return Convert.ToBase64String(hashBytes);
}
  • (Line: 3) Initialized 16-byte array variable to store salt key for password hashing.
  • (Line: 4) Using 'System.Security.Cryptography.RNGCryptoServiceProvider' generating random salt key value.
  • (Line: 6) Using 'System.Security.Cryptography.Rfc2898DeriveBytes()' we hashing our passing by using our salt. Here value '1000' represents the iteration count for encrypting our password.
  • (Line: 7) Taking 20 bytes of data as our password byte value.
  • (Line: 9-13) Here we can observe that our salt value and password byte value are concatenated and stored as finally generated password hash.
Let's add our main method for our user registration.
Logic/AccountLogic:
public async Task<(bool Success, string Message)> UserRegistrationAsync(RegisterVm register)
{
	string message = ResigstrationValidations(register);
	if (!string.IsNullOrEmpty(message))
	{
		return (false, message);
	}

	Users newUser = new();
	newUser.Email = register.Email;
	newUser.FirstName = register.FirstName;
	newUser.LastName = register.LastName;
	newUser.PasswordHash = PasswordHash(register.Password);

	_myCookieAuthContext.Users.Add(newUser);
	await _myCookieAuthContext.SaveChangesAsync();

	var role = await _myCookieAuthContext.Roles.Where(_ => _.Name.ToUpper() == "USER")
	.FirstOrDefaultAsync();

	if (role != null)
	{
		UserRoles userRoles = new();
		userRoles.RoleId = role.Id;
		userRoles.UserId = newUser.Id;

		_myCookieAuthContext.UserRoles.Add(userRoles);
		await _myCookieAuthContext.SaveChangesAsync();
	}

	return (true, string.Empty);
}
  • (Line: 3-7) Checking user registration model. If the model is invalid then terminates execution by returning the error message.
  • (Line: 13) Fetching password hash value.
  • (Line: 15-16) Saving the user details into the database.
  • (Line: 18-19) Fetching the 'User' role which we are going to assign to the user as default on registering.
  • (Line: 21-29) Saving the user-specific roles into the 'UserRoles' database.
Let's define our method definition into the 'IAccountLogic'.
Logic/IAccountLogic:
Task<(bool Success, string Message)> UserRegistrationAsync(RegisterVm register);

Create Registration Razor Pages:

Let's create our user registration razor pages like 'Register.cshtml', 'Register.cshtml.cs' files.
Area/Identity/Pages/Account/Register.cshtml.cs:
using Dot6.Bserver.Cookie.Auth.Models.Auth;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;

namespace Dot6.Bserver.Cookie.Auth.Areas.Identity.Pages.Account;

public class RegisterModel : PageModel
{
    private readonly IHttpContextAccessor _httpContextAccessor;
    private readonly IAccountLogic _accountLogic;
    public RegisterModel(IHttpContextAccessor httpContextAccessor,
    IAccountLogic accountLogic)
    {
        _httpContextAccessor = httpContextAccessor;
        _accountLogic = accountLogic;
    }

    [BindProperty]
    public RegisterVm RegisterForm { get; set; }

    public string ErrorMessage { get; set; }

    public bool IsUserRegistrationSuccessfull { get; set; }

    public async Task<IActionResult> OnGetAsync()
    {
        if (_httpContextAccessor.HttpContext.User.Identity.IsAuthenticated)
        {
            return Redirect("/");
        }
        return Page();
    }

     public async Task<IActionResult> OnPostAsync()
    {
        var registration = await _accountLogic.UserRegistrationAsync(RegisterForm);
        if (!registration.Success)
        {
            ErrorMessage = registration.Message;
        }
        else
        {
            IsUserRegistrationSuccessfull = true;
        }
        return Page();
    }
}
  • (Line: 11-12) Injected 'IHttpContextAccessor', 'IAccountLogic' into the constructor.
  • (Line: 18-19) The 'RegisterVm' property is used for the form model binding. Model binding is enabled by decorating the property with the 'BindProperty'.
  • (Line: 21) The 'ErrorMessage' property displays the form validation error message.
  • (Line: 23) The 'IsUserRegistrationSucceful' property is used to display the registration success message.
  • (Line: 25-36) The 'OnGetAsync' method gets invoked for the HTTP GET requests. This means it will load the registration form.
  • (Line: 27-30) Here we are restricting the authenticated user to not accessing the registration form.
  • (Line: 34-46) The 'OnPostAsync' method gets invoked by the post request(eg: registration form submission).
  • (Line: 36) Invoking the user registration method like 'UserRegistrationAsync()'.
Area/Identity/Pages/Account/Register.cshtml.cs:
@page "/identity/account/register"
@model RegisterModel

<div class="container">
    <div class="row text-center">
        <div class="col">
            @if (!string.IsNullOrEmpty(Model.ErrorMessage))
            {
                <div class="alert alert-danger" role="alert">
                    @Model.ErrorMessage
                </div>
            }
            else if (Model.IsUserRegistrationSuccessfull)
            {
                <div class="alert alert-success" role="alert">
                    Registered Successfuly, now click here to login
                </div>
            }
        </div>
    </div>
    <div class="row">
        <div class="col-md-6 offset-md-3">
            <form method="POST">
                <legend>User Registration</legend>
                <div class="mb-3">
                    <label for="txtEmail" class="form-label">Email</label>
                    <input asp-for="RegisterForm.Email" type="text" class="form-control" id="txtEmail" />
                </div>
                <div class="mb-3">
                    <label for="txtFirstName" class="form-label">First Name</label>
                    <input asp-for="RegisterForm.FirstName" type="text" class="form-control" id="txtFirstName" />
                </div>
                <div class="mb-3">
                    <label for="txtLastName" class="form-label">Last Name</label>
                    <input asp-for="RegisterForm.LastName" type="text" class="form-control" id="txtLastName" />
                </div>
                <div class="mb-3">
                    <label for="txtPassword" class="form-label">Password</label>
                    <input asp-for="RegisterForm.Password" type="password" class="form-control" id="txtPassword" />
                </div>
                <div class="mb-3">
                    <label for="txtConfirmPassword" class="form-label">Confirm Password</label>
                    <input asp-for="RegisterForm.ConfirmPassword" type="password" class="form-control"
                        id="txtConfirmPassword" />
                </div>
                <button type="submit" class="btn btn-primary">Register</button>
            </form>
        </div>

    </div>
</div>
(1)Registration Form:
(2)Registration form with an error message
(3)Successful registration message.

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