How to implement recaptcha v3 in asp net

Introduction

Implementing reCAPTCHA v3 in ASP.NET can help protect your website from spam and abuse. reCAPTCHA v3 is a free service provided by Google that uses advanced risk analysis techniques to determine if a user is a bot or a human.

Step 1: Obtain reCAPTCHA v3 Site Key and Secret Key

The first step is to obtain the reCAPTCHA v3 Site Key and Secret Key from the reCAPTCHA website. You will need to sign up for an API key pair by creating a new project and registering your website.

Step 2: Add reCAPTCHA v3 Script to Your ASP.NET Page

To use reCAPTCHA v3, you need to add the reCAPTCHA script to your ASP.NET page. You can do this by including the following code in the head section of your HTML:

Replace YOUR_SITE_KEY with the reCAPTCHA v3 Site Key obtained in Step 1.

Step 3: Implement reCAPTCHA v3 Verification in Your ASP.NET Code

Next, you need to implement the reCAPTCHA v3 verification in your ASP.NET code. This can be done in the server-side code that handles the form submission or any other relevant code.

Here is an example of how you can implement reCAPTCHA v3 verification in C#:

using System;
using System.Net.Http;
using System.Threading.Tasks;

public class RecaptchaVerifier
{
    private const string RECAPTCHA_VERIFY_URL = "https://www.google.com/recaptcha/api/siteverify";
    private const string RECAPTCHA_SECRET_KEY = "YOUR_SECRET_KEY";

    public async Task VerifyRecaptcha(string responseToken)
    {
        using (var httpClient = new HttpClient())
        {
            var parameters = new Dictionary
            {
                { "secret", RECAPTCHA_SECRET_KEY },
                { "response", responseToken }
            };

            var response = await httpClient.PostAsync(RECAPTCHA_VERIFY_URL, new FormUrlEncodedContent(parameters));
            var responseContent = await response.Content.ReadAsStringAsync();

            dynamic responseObject = JObject.Parse(responseContent);
            return responseObject.success == "true";
        }
    }
}

Replace YOUR_SECRET_KEY with the reCAPTCHA v3 Secret Key obtained in Step 1.

Step 4: Add reCAPTCHA v3 Verification to Your ASP.NET Form

Finally, you need to add the reCAPTCHA v3 verification to your ASP.NET form. This can be done by adding the following code to your form submission code:

string responseToken = Request.Form["g-recaptcha-response"];
RecaptchaVerifier recaptchaVerifier = new RecaptchaVerifier();
bool isVerified = await recaptchaVerifier.VerifyRecaptcha(responseToken);

if (isVerified)
{
    // Process the form submission
}
else
{
    // Display an error message or take appropriate action
}

Make sure to replace “g-recaptcha-response” with the name of the form field that contains the reCAPTCHA response token.

Conclusion

By following these steps, you can easily implement reCAPTCHA v3 in your ASP.NET website to protect it from spam and abuse. The reCAPTCHA v3 verification process helps ensure that only legitimate users can submit forms on your website, improving the overall security and user experience.