How to Secure API in ASP.NET Core Application

Every business must stay current because updating your software is a process that makes it more productive and efficient. New applications are integrated into your current software, accelerating it with the help of APIs (application programming interfaces), so you don’t have to write every feature from scratch.

Consequently, content that is automatically published and distributed across various channels performs better. Furthermore, it is flexible in Web development services and can adjust to changes through data migration, but it differs significantly from the ASP.Net core.

What is web API?

Since WebAPI uses the HTTP Protocol to facilitate communication between clients and web servers so that clients can access data, it can be thought of as an application user interface for web applications or for a web server.

It’s a wise decision because, in addition to being a light-weight, straightforward service, it also adheres to MVC principles, which increase its scalability and resilience.

Furthermore, APIs can be written in any programming language, including Python, C, C++, Ruby on Rails, and Java with the help of middleware.

API security in ASP.Net

As far as we are aware, an API is a procedure that enables software to communicate or exchange data with other parts. In this process, data is sent over a public network between servers and clients, increasing the possibility of data vulnerability. Now let’s get started and examine some important techniques for protecting the APIs in our ASP.Net Core applications.

Authentication and authorization

This is one of the most important and crucial elements of API security. Here, authorization grants or withholds a user’s access to specific application resources based on their access privileges, while authentication serves to verify the user’s identity.

[ApiController]
    [Route("API/[controller]")]
    public class DemoController : ControllerBase
    {
        [Authorize]
        [HttpGet]
        public IActionResult Get()
        {
            //Write your usual code here
            return Ok("Can be accessed only by authenticated users.");
        }
}

Use API keys

API keys are distinct identifiers that are used to pass requests to the API during each call. The code that follows explains how to verify an API key.

[ApiController]
    [Route("API/[controller]")]
 
    public class DemoController: ControllerBase
    {
        private const string API_KEY = "ABCDE12345"; //This is your API key
        [HttpGet]

        public IActionResult Get()
        {
            var apiKey = Request.Headers["Api_Key"].FirstOrDefault();
            if (apiKey != API_KEY)
                return Unauthorized();
            //Write your usual code here
            return Ok("The API key is valid. Authenticated, successful."
        }
}

Additionally, API keys can be used in applications to authenticate users.

Use cross-origin resource sharing

It’s also referred to as CORS, and it keeps unauthorized users from using other domains to access your APIs. Use the following code snippet to enable CORS in an ASP.Net Core 7 application at the action level.

public class BookController : ApiController
    {
        [EnableCors(origins: "http://localhost:8095/",
        headers: "*", methods: "*")]
        public IEnumerable<string> Get()
        {
            return new string[] {"Mastering C# 8.0", "Joydip Kanjilal"};
        }
    }

Use API versioning

Versioning your APIs is an additional measure that enhances API security. Without affecting current clients, it enables you to upgrade your API and phase out less secure versions. To use the MapToApiVersion attribute and perform the following action, simply install the ASP.Net API versioning package for NuGet.

[HttpGet]
    [MapToApiVersion("3.0")]
    public string Get()
    {
        return books;
    }

Use logging and monitoring

Monitoring seeks to identify and detect app failures, while logging provides comprehensive information about the behavior of your application. You can clearly see API usage and security concerns related to your API with the aid of these features. Additionally, you benefit from ASP.Net’s default built-in logger.

public class DemoController: Controller
    {
        private readonly ILogger _logger;

        public DemoController(ILogger <DemoController> logger)
        {
            _logger = logger;
        }

        public IActionResult Index()
        {
            _logger.LogInformation("Inside the Index action method");
            return View();
        }

        public IActionResult Test()
        {
            _logger.LogInformation("Inside the Test action method");
            return View();
        }
    }

Use rate limiting

Rate limiting, which lets you set a limit on the maximum number of calls an API can receive in a given amount of time, is essential for safeguarding your API against security flaws.

Token based Authentication

Each authenticated user receives a unique token as part of this authentication security. Once the user’s identity has been confirmed, the token is generated once. JSON Web Tokens are advised because they are dependable in information transmission, guaranteeing that data is not lost or misused.

Conclusion

Since APIs are always changing, it’s important to maintain their high level of security by only storing the data that is actually needed and regularly clearing out outdated or superfluous information. Taking into consideration the aforementioned elements to create a highly secure API.