Authentication and Authorization in .NET Core

Quick Overview:
As the tech business development marketplace evolves with the days the security risks related to it take a surge. This leads to the need for restricting access to a few resources within the application to authorized users only as it allows the server to determine which resources the user should have access to. In this blog post, we will have a deeper look into the Authentication and Authorization in .NET Core to ensure the safety and security of your .NET business application.

Understanding Authentication in .NET Core

Authentication in .NET Core refers to the process of determining the identity of a user. Authorization, on the other hand, refers to the process of determining whether a user has access to a resource. Explaining it further Authentication in .NET Core is a process where the identity of the users is verified by those who wish to attempt to access an application or a system. Authentication further ensures that the real user only is accessing the said data. In .NET Core Authentication generally requires validating the user credentials such as usernames, and passwords, against a trusted source. Such as a database or an identity provider.

Authorization on the other hand is the process of determining the actions authenticated that users can perform within the application. It ensures that the authenticated users here have access to resources and functionalities that align with their assigned or granted roles and permissions.

Implementing the JWT Authentication .NET Core

The JSON Web Tokens or JWT are a renowned way to implement authentication within modern web applications referring to their stateless nature and scalability. In .NET Core JWT authentication requires generating the token upon successful login and validating it with each subsequent request.

You can refer to the steps given below to implement JWT authentication in .NET Core:

Step 1: Install the required packages

dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer

Step 2: Configure the JWT authentication middleware ‘Startup.cs’

using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.IdentityModel.Tokens;
using System;
using System.Text;

public void ConfigureServices(IServiceCollection services)
{
    // Other configurations within the code...

    services.AddAuthentication(options =>
    {
        options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
    }).AddJwtBearer(options =>
    {
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = "yourIssuer",
            ValidAudience = "yourAudience",
            IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes("yourSecretKey"))
        };
    });

    // Other services...
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // Middleware configurations...

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

    // Other configurations within the code...
}

Step 3: Generate the JWT tokens after the successful authentication and then include them within the responses.

Explore The Role Based Authorization in .NET Core

The Role Based Authorization in .NET Core grants access to the resources based on the predefined roles that are already assigned to the users. Let us now look at the steps to implement the same:

Step 1: Define the roles and assign them to the users.

Step 2: Create the authorization policies that are based on the roles in ‘Startup.cs’

public void ConfigureServices(IServiceCollection services)
{
    // Other configurations...

    services.AddAuthorization(options =>
    {
        options.AddPolicy("AdminOnly", policy =>
            policy.RequireRole("Admin"));
    });

    // Other services...
}

Step 3: Apply the authorization policies to controllers or the actions using the ‘[Authorize]’ attribute.

[Authorize(Policy = "AdminOnly")]
public IActionResult AdminPanel()
{
    // This is the action logic for admin panel
}

Creating Custom Authentication Schemes in .NET Core

Oftentimes, inbuilt .NET Authentication mechanisms may not suffice for the specific requirements. Under such cases, your development team can create custom authentication schemes within the .NET Core.

Step 1: Implement a Custom Authentication handler by inheriting from the ‘AuthenticationHandler<T>’ class.

public class CustomAuthenticationHandler: AuthenticationHandler<AuthenticationSchemeOptions>
{
    protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
    {
        // Here is the Authentication logic implemented here
    }
}

Step 2: Configure the authentication middleware to use the custom scheme.

public void ConfigureServices(IServiceCollection services)
{
    // Other configurations...

    services.AddAuthentication(options =>
    {
        options.DefaultAuthenticateScheme = "CustomScheme";
        options.DefaultChallengeScheme = "CustomScheme";
    }).AddScheme<AuthenticationSchemeOptions, CustomAuthenticationHandler>("CustomScheme", null);

    // Other services...
}

Step 3: Validating the User Credentials and establishing the identity within the custom authentication handler.

Authentication and Authorization – Security Best Practices

Though the Authorization and Authentication involves the way to make your business application secure following certain best practices you can get the most out of your Authentication and Authorization in .NET Core business applications.

• Use ASP.NET Core Identity: You can use it for handling the authorization and authentication as it provides a strong framework to manage users, passwords, role-based access, and claims-based authorization.
• Enable Multi-Factor Authorization (MFA): It is crucial to add an extra layer of security enabling the MFA which helps verify the user identity via multiple ways like SMS, email, and authenticator apps.
• Secure Sensitive Data With HTTPS: Use HTTPS to encrypt the data within the transit between the client and the server. This prevents the interception and the tampering of sensitive information including the authentication credentials.
• Use The Storage For Secrets: Store your sensitive information like the API keys, connection strings, and other secrets. You can use tools like Azure Key Vault or the AWS Secrets Manager and manage the access securely.
• Update and Patch Dependencies: Make sure that your .NET Core libraries and dependencies are up to date with the latest security patches. You must review and update all the third-party packages to mitigate the vulnerabilities.
• Monitor and Log Authentication Events: Implement the logging and monitoring for the authentication and authorization events. This will help them detect and respond to the authorized access attempts and the security breaches.
• Prevent Injection Attacks: Validate and sanitize the user input to protect against SQL injection, cross-site scripting, and other injection attacks. You can use parameterized queries and inbuilt validation frameworks to ensure data integrity.
• Leverage OAuth2 and OpenID Connect For External Authentication: To integrate external login providers such as Google, Facebook, or Microsoft, use OAuth2 and OpenID Connect. These protocols present secure methods for user authentication and authorization.

Conclusion

Implementing robust authentication and authorization mechanisms is crucial for the security and integrity of any web application providing comprehensive and flexible tools to manage authentication and authorization effectively. By leveraging built-in middleware, policies, roles, and custom handlers, you can create secure applications tailored to your specific needs. By following best practices and keeping safety at the forefront of your development process, you can protect your application and users’ data from unauthorized access and other security threats.