Using Google ReCaptcha - recaptcha

Question

I am keen on using Google ReCaptcha. I have got the captcha on the page using the public key but don't know how to use the private key in my form processor document:
<?php
//SMTP SETTINGS
require 'PHPMailerAutoload.php';
$mail = new PHPMailer;
$mail->isSMTP(); // Set mailer to use SMTP
$mail->Host = 'smtp.webhost.co.nz'; // Specify main and backup server
$mail->SMTPAuth = true; // Enable SMTP authentication
$mail->Username = ‘xxxxx#xxxxxxxx.co.nz'; // SMTP username
$mail->Password = ‘xxxxx##xxxxxx’; // SMTP password
$mail->SMTPSecure = 'ssl'; // Enable encryption, 'ssl' also accepted
$mail->Port = 465;
$mail->isHTML(true); // Set email format to HTML
//SMTP SETTINGS
$name = $_POST['name'];
$email = $_POST['email'];
$message = $_POST['message'];
print_r($_POST);
$mailheader = "From: $email";
$to = "tony#finelinecreative.co.nz"; // Here is email send to
$subject = "Finelinecreative Enquiry";
$message = "Name: $name<br/>Email: $email<br/>Message: $message";
// Send the mail
$mail->From=$mail->Username;
$mail->FromName = 'finelinecreative';
$mail->addAddress($to);
$mail->addReplyTo($email, $email);
$mail->Subject = $subject;
$mail->Body = $message;
$mail->IsHTML(true);
$result = $mail->send();
header('location: http://www.finelinecreative.co.nz/index.php/thanks');
?>
Ideas please?

Answer 1

There's a great tutorial at https://codeforgeek.com/2014/12/google-recaptcha-tutorial/ that explains it pretty well.
In essence, you're checking if the $_POST variable 'g-recaptcha-response' exists (which, by including recaptcha on your form, is sent along with the other values on the form). If it is, you send a file_get_contents call (sending the secret key, the g-recaptcha-response POST value, and the user's IP address). You decode the result of that (which is sent as JSON, and you probably want to access it as key-value pairs), and find out whether the query was successful.
This is the relevant portion of their implementation.
if(isset($_POST['g-recaptcha-response'])){
$captcha=$_POST['g-recaptcha-response'];
}
if(!$captcha){
echo '<h2>Please check the the captcha form.</h2>';
exit;
}
$secretKey = "Put your secret key here";
$ip = $_SERVER['REMOTE_ADDR'];
$response=file_get_contents("https://www.google.com/recaptcha/api/siteverify?secret=".$secretKey."&response=".$captcha."&remoteip=".$ip);
$responseKeys = json_decode($response,true);
if(intval($responseKeys["success"]) !== 1) {
echo '<h2>You are spammer ! Get the #$%K out</h2>';
} else {
// Send the email. In your case, you can wrap pretty all of your preprocessor in this.
}