Get every incoming http request in .net framework

I need to check every incoming http request in .net framework and decrypt data if needed.
How can I do it?
I know that in .net core it's done with middleware but how is it done in .net framework?

I saw this code, in using http handler but i need more info:

public void ProcessRequest(HttpContext context)  
    {  
        HttpRequest request = context.Request;  
        HttpResponse response = context.Response;  
  
        string imageURL = null;  
        // Perform a case-insensitive comparison.  
        if (request.UrlReferrer != null)  
        {   
            if(String.Compare(request.Url.Host,             request.UrlReferrer.Host,true,CultureInfo.InvariantCulture) ==0)  
            {  
                // The requesting host is correct.  
                // Allow the image (if it exists).  
                imageURL = request.PhysicalPath;  
                if (!File.Exists(imageURL))  
                {  
                    response.Status = "Image Not Found";  
                    response.StatusCode = 404;  
                }  
                else  
                {   
                }  
            }  
        }  

The provided code appears to be a method within an HTTP handler. Typically, HTTP handlers are defined in classes that derive from the IHttpHandler interface in .NET Framework. You can create your own HTTP module, as shown below, and map this module in your Web.config file:

public class SecurityModule : IHttpModule
{
    public void Init(HttpApplication app)
    {
        //Here you can register for any events, like BeginRequest or 
        AuthenticateRequest or PostAuthenticateRequest
        app.PostAuthenticateRequest += OnPostAuthenticateRequest;
    }

    public void Dispose()
    {
    }

    private static void OnPostAuthenticateRequest(object source, EventArgs eventArgs)
    {
        // Check if request contains encryption-key
        var request = HttpContext.Current.Request;
        if (request.Headers.ContainsKey("Encryption-Key"))
        {
            // Decrypt request body
            var requestBody = Encryption.Decrypt(request.Body.ToString(), request.Headers["Encryption-Key"]);
            request.Body = requestBody;
        }
    
        // Here you can write code to be executed on PostAuthenticationEvent
        HttpContext.Current.Response.Write("Executing post authentication code..." + "<br/>\r\n");
   }
}

The code above first checks if the incoming HTTP request contains an encryption key in its headers. If it does contain one, then it decrypts the request body using the Encryption.Decrypt() method and sets the decrypted content to the request body property to view the decrypted data. The decrypted request is then passed onto the next step in the pipeline.
In addition, the OnPostAuthenticateRequest method provides opportunity to place any other code you may need to handle the incoming request, as required, such as modifying headers or checking the request data.

This way, your SecurityModule will execute its OnPostAuthenticateRequest method, which should contain the provided code, whenever an HTTP request is received. Don't forget to register your module in the Web.config file.

Hope this helps