Google recaptcha with PHP - sign up controller

controller-sign-up.php

<?php

if (array_key_exists('signUpAttempt', $_POST)) {

	$captcha = isset($_POST['g-recaptcha-response']) ? $_POST['g-recaptcha-response'] : null;

	// ultimately these could be constants in a "secrets" file
	// 	aka stored as environment variables
	#$captchaPublic = constant('CAPTCHA_PUBLIC');
	#$captchaSecret = constant('CAPTCHA_SECRET');
	$captchaPublic = "my-public-key-here";
	$captchaSecret = "my-secret-key-here";

	$res = json_decode(file_get_contents("https://www.google.com/recaptcha/api/siteverify?secret=".$captchaSecret ."&response=".$captcha));

	if($res->success === true){
		// ok! don't do anything
	} else{
		print "Error: Human check failed";
		exit();
	}
	
	// continue sign up process as normal
	print "You don't seem to be a robot";
	exit();

	#$email = $_POST['email'] ?? '';
	#$password = $_POST['password'] ?? '';

	// ...

}
?>