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Integrating Google Captcha

I've usually written my own code for captcha and bot intervention, but google is making it very easy now.

Google's own documentation - Just click on "My reCAPTCHA" to create one.

Client-side HTML

Inside HEAD: 
<script src='https://www.google.com/recaptcha/api.js'></script>

Inside FORM (method POST):
<div class="g-recaptcha" data-sitekey="YOUR-KEY"></div>

Server-side PHP (POST action)

// Sjekk captcha først.
isset($_POST['g-recaptcha-response'])) {
	$google_captcha_response = file_get_contents(
		"https://www.google.com/recaptcha/api/siteverify".
		"?secret=YOUR-KEY".
		"&response=". $_POST['g-recaptcha-response'] .
		"&remoteip=". $_SERVER['REMOTE_ADDR']
	);
	$success_result = json_decode($google_captcha_response, true);
	if ($success_result['success'] != true)
		exit('Confirm that you\'re not a robot... <a href="javascript:history.back()">Try again</a>');
	
	// Human verified, continue...
}