How to Verify Google reCAPTCHA v3 on the Server Side in PHP?

How to Verify Google reCAPTCHA v3 on the Server Side in PHP

Problem: You've implemented Google reCAPTCHA v3 with a checkbox on the front end, but you're facing difficulties validating it on the server side. The form is being submitted even when the captcha is invalid.

Solution:

To effectively handle Google reCAPTCHA v3 validation on the server side, it's crucial to use POST requests. Here's a solution:

<code class="php">function isValid()
{
    try 
    {
        $url = 'https://www.google.com/recaptcha/api/siteverify';
        $data = [
            'secret'   => '[YOUR SECRET KEY]',
            'response' => $_POST['g-recaptcha-response'],
            'remoteip' => $_SERVER['REMOTE_ADDR']
        ];

        $options = [
            'http' => [
                'header'  => "Content-type: application/x-www-form-urlencoded\r\n",
                'method'  => 'POST',
                'content' => http_build_query($data)
            ]
        ];

        $context  = stream_context_create($options);
        $result = file_get_contents($url, false, $context);
        return json_decode($result)->success;
    }
    catch (Exception $e) 
    {
        return null;
    }
}</code>

Explanation:

• The isValid() function is crafted to verify reCAPTCHA v3 using a POST request.
• It sends the secret key, captcha response, and user's IP address to Google's API.
• The function parses the API's response and returns true if the captcha is valid, false if it's invalid, and null if an error occurs during the request.

Usage:

In your code, simply write:

if (isValid()) {
  // The user has passed the captcha validation.
} else {
  // The user has failed the captcha validation.
}

Note: Ensure to replace [YOUR SECRET KEY] with your actual reCAPTCHA secret key in the provided code snippet.

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