Secure Authentication and Authorization in .NET Core

Apr 01, 2025

Authentication and authorization are essential components of any web application, ensuring the security and proper access control for users. In NET Core, these concepts play a crucial role in protecting resources and determining user permissions.
 

Authentication in NET Core

Authentication is the process of verifying the identity of a user, ensuring they are who they claim to be. This is typically done by presenting credentials, such as a username and password, and validating them against a trusted source, such as a database or an external authentication provider. Once authenticated, the user is assigned an identity, which is then used for subsequent authorization checks.

 

Authentication in NET Core

Authentication in NET Core revolves around the concept of authentication schemes. An authentication scheme represents a specific method or protocol used to authenticate users. NET Core supports various authentication schemes out of the box, including cookie authentication, JWT bearer authentication, and external authentication providers like OAuth and OpenID Connect.

 

Understanding Authentication Schemes

Authentication schemes are registered in the application’s startup class using the AddAuthentication method. This method allows you to specify one or more authentication schemes and their respective options. For example, to enable cookie authentication, you can use the AddCookie
 

services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
    .AddCookie(options =>
    {
        // Configure CookieAuthenticationDefaults options
    });

 

Configuring Cookie Authentication

To configure cookie authentication, you need to specify the authentication scheme as CookieAuthenticationDefaults.AuthenticationScheme and provide the necessary options, such as the cookie name, login path, and authentication endpoint. Here's an example:

services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
    .AddCookie(options =>
    {
        options.Cookie.Name = "MyCookie";
        options.LoginPath = "/Admin/Login";
    });
In this example, the cookie authentication middleware is configured to use the scheme named “MyCookie” and redirect users to the “/Admin/Login” page if they try to access a protected resource without being authenticated. The options object allows you to customize various aspects of cookie authentication, such as cookie expiration and sliding expiration.
 

Implementing Claim-Based Authentication

A claim represents a piece of information about the user, such as their name, email address, or role. By using claims, you can easily extend the user’s identity with additional data and make authorization decisions based on these claims.

In NET Core, claim-based authentication is implemented using the ClaimsIdentity and ClaimsPrincipal classes. The ClaimsIdentity represents a collection of claims associated with a user, while the ClaimsPrincipal represents the user's identity as a whole. When a user is authenticated, their claims are stored in a ClaimsPrincipal, which is then attached to the current request's HttpContext.User property.

To implement claim-based authentication, you need to create and populate a ClaimsIdentity object with the relevant claims. This can be done during the authentication process, typically in a custom authentication handler. Here's an example of how to create a ClaimsIdentity with a username claim:
 

var claims = new List<Claim>
{
    new Claim(ClaimTypes.Name, "Himanshu")
};

var identity = new ClaimsIdentity(claims, "MyAuthenticationScheme");

var principal = new ClaimsPrincipal(identity);

await HttpContext.SignInAsync(principal);

 

External Authentication Providers

External authentication allows users to sign in to your application using their existing accounts from popular platforms like Google, Facebook, Twitter, and Microsoft. 
To enable external authentication, you need to configure the desired authentication provider and register it in your application’s startup class.
 

services.AddAuthentication()
    .AddGoogle(options =>
    {
        options.ClientId = "YOUR_GOOGLE_CLIENT_ID";
        options.ClientSecret = "YOUR_GOOGLE_CLIENT_SECRET";
    });

 

Securing APIs with JWT Bearer Authentication

.NET Core provides built-in support for securing APIs using JSON Web Tokens (JWT) and the JWT bearer authentication scheme. JWTs are self-contained tokens that contain information about the user and their permissions. By validating the integrity and authenticity of a JWT, you can trust the claims it contains and authenticate API requests.

To enable JWT bearer authentication, you need to configure the authentication scheme and provide the necessary options, such as the token validation parameters and the issuer signing key. Here’s an example of configuring JWT bearer authentication:

services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(options =>
    {
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = "YOUR_ISSUER",
            ValidAudience = "YOUR_AUDIENCE",
            IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes("YOUR_SIGNING_KEY"))
        };
    });

In this example, the AddJwtBearer extension method is used to configure JWT bearer authentication. The TokenValidationParameters object is set with the necessary validation rules, such as validating the issuer, audience, and the issuer's signing key. You need to replace the placeholder values with your own values specific to your JWT setup.

With JWT bearer authentication enabled, API endpoints can be protected by applying the [Authorize] attribute to the corresponding controller or action. This ensures that only requests with valid and authenticated JWTs are allowed access to the protected resources.
 

Maintain secure Authorization

Authorization in NET Core is primarily controlled through the use of the [Authorize] attribute. This attribute can be applied at the controller or action level to restrict access to specific components of your application. By default, the [Authorize] attribute allows only authenticated users to access the protected resource.

The Role of Authorize Attribute : 
For example, you can use the [Authorize(Roles = "Admin")] attribute to restrict access to administrators only. This ensures that only users with the "Admin" role can access the protected resource.

Restricting Access with Policies :
While the [Authorize] attribute provides a simple way to restrict access, ASP.NET Core also supports more advanced authorization policies. Authorization policies allow you to define fine-grained rules for determining whether a user is authorized to perform a specific action.

To use authorization policies, you need to define them in your application’s startup class using the AddAuthorization method. Here's an example:
 

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

Rrole-based authorization can be implemented using the built-in role-based authentication system or by integrating with an external identity provider, such as Active Directory or Azure AD.

 

Implementing Two-Factor Authentication

Two-factor authentication (2FA) adds an extra layer of security to the authentication process by requiring users to provide additional verification, typically in the form of a one-time password or a biometric factor. Implementing 2FA can significantly reduce the risk of unauthorized access, especially for sensitive applications or those handling confidential information.
 

To implement two-factor authentication, you need to configure the desired authentication providers, such as SMS, email, or authenticator apps, and register them in your application’s startup class. You also need to configure the necessary options, such as the message templates or the issuer signing key.

By enabling two-factor authentication, you provide an additional layer of security that can help protect user accounts from unauthorized access, even if their credentials are compromised.
 

Protecting Against Common Security Vulnerabilities

When implementing authentication and authorization in your application, it’s crucial to be aware of common security vulnerabilities and take appropriate measures to prevent them. By understanding these vulnerabilities and following security best practices, you can ensure the integrity and confidentiality of user data.

Some common security vulnerabilities to consider when implementing authentication and authorization include:

  • Cross-Site Scripting (XSS): Protect against XSS attacks by properly encoding user input and validating data before rendering it in HTML or JavaScript.
  • Cross-Site Request Forgery (CSRF): Implement CSRF protection mechanisms, such as anti-forgery tokens, to prevent attackers from executing unauthorized actions on behalf of authenticated users.
  • Brute-Force Attacks: Implement account lockout policies and rate limiting to protect against brute-force attacks that attempt to guess user credentials.
  • Session Management: Use secure session management techniques, such as session timeouts, secure cookie attributes, and session regeneration, to prevent session hijacking or session fixation attacks.
  • Password Storage: Store passwords securely by using strong hashing algorithms, salting, and iteration counts to protect against password cracking attempts.

By addressing these vulnerabilities and following security best practices, you can minimize the risk of unauthorized access, data breaches, and other security incidents.
 

Conclusion:

Authentication and authorization are critical components of building secure and robust web applications in .Net Core. By understanding the concepts and leveraging the powerful features provided by. NET Core, developers can implement robust security measures to protect their applications and ensure that users access resources securely and efficiently.

Will AI Replace Developers? Exploring the Future of Coding in the Age of Artificial Intelligence
Mar 31, 2025

As AI technology rapidly evolves, the question arises: Will it replace developers, or will it serve as a powerful tool to enhance their coding capabilities?   A few years ago, AI in software development was just a futuristic idea. Today, tools like GitHub Copilot, ChatGPT, Amazon CodeWhisperer, and AI-powered debugging assistants are transforming how we write, test, and deploy code. But does this mean AI will replace developers? Not exactly. Instead, it’s reshaping their role—making developers faster, smarter, and more efficient than ever before. How AI is Revolutionizing Development  AI is already changing the game in multiple ways: Instant Code Generation & Autocompletion AI tools can predict and generate entire functions, reducing boilerplate code. They suggest optimized SQL queries, API calls, and even React components in real time. Example: GitHub Copilot can turn a simple comment (// fetch user data from API) into a fully functional code block. Expansion: Some AI models can now generate entire project scaffolds based on a high-level description, speeding up prototyping. Smarter Debugging & Error Detection AI-powered linters and debuggers (like DeepCode, Tabnine, or ChatGPT) analyze code for vulnerabilities and suggest fixes. Some tools predict runtime errors before execution, saving hours of troubleshooting. Expansion: AI can analyze historical bug data to predict where new errors might occur, acting as a preventive measure. Automated Testing & Deployment AI-driven testing frameworks (e.g., Testim, Applitools) auto-generate test cases and detect UI changes. CI/CD pipelines now use AI to optimize build times and deployment strategies. Expansion: AI can simulate load testing scenarios and auto-adjust infrastructure based on traffic patterns. Enhanced Learning & Onboarding Junior developers can ask AI for explanations instead of digging through Stack Overflow. AI helps bridge knowledge gaps by suggesting best practices and modern frameworks. Expansion: AI-powered IDEs (like Cursor, VS Code with AI plugins) provide real-time mentorship, making learning faster. What AI Can’t Replace (Yet) While AI is powerful, it still has critical limitations: Deep Problem-Solving & Business Logic AI can generate code, but it doesn’t truly understand business requirements like a human. Complex architectural decisions (monolith vs. microservices, database optimization) still need human expertise. Expansion: AI may struggle with legacy systems where documentation is sparse, requiring human intuition. Creativity & Innovation AI can assist but not invent—truly novel solutions (like a new algorithm or UX paradigm) require human ingenuity. Designing scalable systems is still an art + science that AI can’t fully replicate. Expansion: AI lacks true intuition—it can’t foresee edge cases the way experienced developers can. Team Collaboration & Soft Skills AI can’t negotiate with stakeholders, explain trade-offs, or lead a sprint planning session. Pair programming with AI? Useful, but not the same as human brainstorming. Expansion: AI can’t mentor junior devs emotionally or navigate office politics—key aspects of career growth.   The Future: AI as a Superpower for Developers Rather than replacing developers, AI is becoming the ultimate coding sidekick. The most successful developers will be those who: Leverage AI for repetitive tasks (boilerplate code, debugging, docs). Focus on high-value skills (system design, security, optimization). Adapt continuously—AI tools evolve fast, and staying updated is key. Here’s a list of AI tools : GitHub Copilot – Powered by OpenAI’s Codex, GitHub Copilot offers code suggestions, completions, and entire function generation based on the context of your code. ChatGPT – A versatile AI by OpenAI that can assist with writing code, answering technical questions, debugging, and offering suggestions on a wide variety of coding topics. Amazon CodeWhisperer – An AI-powered code completion tool from Amazon, designed to generate code suggestions and snippets based on the context of your code, with an emphasis on AWS services and cloud-based applications. Tabnine – An AI code completion tool that integrates with various IDEs, offering context-based code suggestions across multiple programming languages. Kite – A code completion tool that uses AI to provide real-time suggestions and documentation for Python, JavaScript, Go, and other languages. Codex – OpenAI’s powerful model specifically trained for understanding and generating code, forming the basis for tools like GitHub Copilot. IntelliCode – Microsoft’s AI-powered code completion and suggestion system built into Visual Studio and Visual Studio Code, tailored for improving code quality and productivity. Sourcery – A Python-focused AI tool that automatically suggests code improvements, refactoring, and optimizations. Ponicode – Offers AI-driven code generation and automated documentation tools to simplify the development process. CodeGuru – Amazon’s AI tool for code reviews that uses machine learning to detect bugs, performance issues, and security vulnerabilities in code. Replit Ghostwriter – An AI code assistant integrated with Replit, which helps developers write and debug code interactively. Hugging Face Transformers – Though primarily focused on NLP, Hugging Face also provides pretrained models for code generation and completion tasks. Jina AI – A tool for building AI-powered applications and search engines, supporting code generation and multimodal data processing. These tools are designed to assist developers by automating mundane tasks, improving code quality, and speeding up development through AI-driven suggestions and completions.   Will AI Replace Jobs? No—But It Will Change Them Low-code/no-code tools may reduce demand for basic CRUD apps, but complex systems will still need experts. The role of a developer is shifting from "writing code" to "solving problems with AI-assisted efficiency." Expansion: Future developers may work more as AI trainers, fine-tuning models for specific business needs. Final Thoughts: Embrace the Change AI won’t replace developers—but developers who use AI will replace those who don’t. The key is to adapt, upskill, and integrate AI into workflows rather than resist it. What do you think? Will AI make developers obsolete, or will it just make them unstoppable?  What do you think? Let me know in the comments!

API Versioning with .NET 8.0
Feb 11, 2025

Why API Versioning? API versioning allows developers to: Introduce new API features without breaking existing clients. Deprecate older API versions in a controlled manner. Provide clear communication about supported versions.   With .NET 8.0, setting up API versioning is straightforward and efficient. Let’s explore how to implement it. In the Program.cs file, configure services for controllers and API versioning: using Microsoft.AspNetCore.Mvc; var builder = WebApplication.CreateBuilder(); // Add services for controllers and API versioning builder.Services.AddControllersWithViews(); builder.Services.AddApiVersioning(o => { o.ReportApiVersions = true; // Include version information in responses }); var app = builder.Build(); // Map default controller route app.MapDefaultControllerRoute(); app.Run(); Nuget Package Name : Microsoft.AspNetCore.Mvc.Versioning Implementing a Versioned Controller Define a versioned controller to handle API requests. Use the ApiVersion attribute to specify the API version and the route. [ApiVersion("1.0")] [ApiVersion("2.0")] [Route("api/v{version:apiVersion}/[controller]")] [ApiController] public class HelloWorldController : ControllerBase { [HttpGet] public IActionResult Get(ApiVersion apiVersion) => Ok(new { Controller = GetType().Name, Version = apiVersion.ToString(), Message = "This is version 1 of the API" }); [HttpGet, MapToApiVersion("2")] public IActionResult GetV2(ApiVersion apiVersion) => Ok(new { Controller = GetType().Name, Version = apiVersion.ToString(), Message = "This is version 2 of the API" }); } Key Points in the Code ApiVersion("1"): Specifies that this controller handles API version 1. Route("api/v{version:apiVersion}/[controller]"): Dynamically includes the API version in the route. ApiVersion** parameter**: Captures the requested version and includes it in the response. Endpoint : GET http://localhost:51346/api/v1/HelloWorld Response : {     "Controller": "HelloWorldController",     "Version": "1",     "Message": "This is version 1 of the API" } Endpoint : GET http://localhost:51346/api/v2/HelloWorld Response : {     "Controller": "HelloWorldController",     "Version": "2",     "Message": "This is version 2 of the API" } Conclusion API versioning in .NET 8.0 is a simple yet powerful feature for managing evolving APIs. By integrating AddApiVersioning and leveraging attributes like ApiVersion and Route, developers can efficiently support multiple API versions without sacrificing maintainability. If you have further questions or insights, feel free to share them in the comments!

.NET Performance Analysis: Newtonsoft.Json vs System.Text.Json
Jul 23, 2024

In the world of .NET development, handling JSON serialization and deserialization is a common task, especially when dealing with web APIs, configuration files, and data interchange between systems. Two prominent libraries for JSON processing in the .NET ecosystem are Newtonsoft.Json (often referred to simply as Newtonsoft) and System.Text.Json. In this article, we'll compare and contrast these two libraries, exploring their features, examples, advantages, and disadvantages. Newtonsoft.Json Newtonsoft.Json, developed by James Newton-King, has been the go-to library for JSON serialization and deserialization in the .NET ecosystem for many years. It offers a wide range of features and has garnered widespread adoption among developers. Let's explore some of its characteristics:   Features of Newtonsoft.Json   Flexible and Robust: Newtonsoft.Json provides comprehensive support for JSON serialization and deserialization, handling complex object graphs, custom conversions, and nullable types effortlessly. Customization Options: Developers can customize the serialization and deserialization process using attributes, custom converters, and serialization settings, allowing fine-grained control over JSON representation. Widely Adopted: Newtonsoft.Json is battle-tested and widely adopted in the .NET community, with extensive documentation, tutorials, and community support available.   using Newtonsoft.Json; // Serialization string json = JsonConvert.SerializeObject(myObject); // Deserialization MyObject obj = JsonConvert.DeserializeObject<MyObject>(json); System.Text.Json System.Text.Json, introduced in .NET Core 3.0 and later versions, is Microsoft's built-in JSON processing library, aiming to provide a modern, high-performance alternative to Newtonsoft.Json. While it may not offer the same level of features and flexibility as Newtonsoft.Json, it focuses on performance and seamless integration with the .NET ecosystem. Features of System.Text.Json Performance: System.Text.Json is optimized for performance, offering faster serialization and deserialization compared to Newtonsoft.Json in certain scenarios. Built-in Support: It seamlessly integrates with other .NET features such as async/await, streams, and memory management, making it a natural choice for .NET Core and .NET 5+ projects. Minimalistic API: System.Text.Json provides a minimalistic API surface, emphasizing simplicity and ease of use for common scenarios. using System.Text.Json; // Serialization string json = JsonSerializer.Serialize(myObject); // Deserialization MyObject obj = JsonSerializer.Deserialize<MyObject>(json);   Advantages and Disadvantages Newtonsoft.Json Advantages Comprehensive feature set with extensive customization options. Widely adopted with a large community and ecosystem. Mature and battle-tested library. Disadvantages Performance may degrade for large datasets compared to System.Text.Json. Requires additional dependencies for .NET Core and .NET 5+ projects.    System.Text.Json Advantages Optimized for performance, especially in scenarios with large datasets. Built-in support in .NET Core and .NET 5+, eliminating the need for additional dependencies. Seamless integration with other .NET features. Disadvantages Less feature-rich compared to Newtonsoft.Json, lacking some advanced customization options. Limited community support and fewer resources compared to Newtonsoft.Json. [Benchmark] public void NewtonsoftDeserializeIndividualData() { foreach (var user in serializedTestUsersList) { _ = Newtonsoft.Json.JsonConvert.DeserializeObject<User>(user); } } [Benchmark] public void MicrosoftDeserializeIndividualData() { foreach (var user in serializedTestUsersList) { _ = System.Text.Json.JsonSerializer.Deserialize<User>(user); } } Results: Data Method Count Mean  Ratio  Allocated Alloc Ratio Newtonsoft 10000 15.974 ms 1.00 35.5 MB 1.00 Microsoft 10000 8.472 ms 1.00 3.96 MB 1.0      Conclusion In the realm of JSON serialization and deserialization within the .NET landscape, our benchmarks present a compelling case. Despite claims of high performance from Newtonsoft.Json, the results unequivocally demonstrate that Microsoft’s System.Text.Json consistently outperforms its counterpart. Whether handling large or small datasets, System.Text.Json showcases superior speed and memory efficiency.

Himanshu Pranami

About the Author

Himanshu Pranami

I'm working as a Software Developer at MagnusMinds IT Solution, bringing over 4 years of professional experience. My expertise spans a range of technologies, including the .NET Framework, .NET Core, MVC, ASP.NET, Entity Framework, ADO.NET, SQL, PostgreSQL, C#, Azure DevOps, and Microservices.