What are some best practices for securely implementing Captcha functionality in PHP forms?

One best practice for securely implementing Captcha functionality in PHP forms is to use a reliable Captcha service like Google reCAPTCHA. This service provides a more secure and user-friendly way to verify that a user is not a bot. Additionally, it is important to properly validate the Captcha response on the server-side to ensure that the form submission is coming from a legitimate user. 

// Verify Captcha response
$secretKey = "YOUR_SECRET_KEY_HERE";
$responseKey = $_POST['g-recaptcha-response'];
$userIP = $_SERVER['REMOTE_ADDR'];

$url = "https://www.google.com/recaptcha/api/siteverify?secret=$secretKey&response=$responseKey&remoteip=$userIP";
$response = file_get_contents($url);
$responseKeys = json_decode($response, true);

if(intval($responseKeys["success"]) !== 1) {
    // Captcha verification failed
    // Handle error accordingly
} else {
    // Captcha verification successful
    // Process form submission
}

Keywords

Captcha PHP forms Security Implementation Best practices

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