You can get ReCaptcha keys here:
https://www.google.com/recaptcha/intro/index.html
ReCaptcha secret key: Use this for communication between your site and Google. Be sure to keep it a secret.
ReCaptcha site key: Use this in the HTML code your site serves to users.
All you need to get this working is to edit values of $secret_key and data-sitekey. Just enter your values and it should work even in localhost. I believe that code is self-explanatory:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>No Captcha ReCaptcha</title>
</head>
<body>
<?php
// Get submited data.
$g_recaptcha_response = filter_input(INPUT_POST, 'g-recaptcha-response');
$msg = filter_input(INPUT_POST, 'msg');
// Check if set.
if (isset($g_recaptcha_response)) {
// Your secret key.
$secret_key = 'your-secret-key';
$google = 'https://www.google.com/recaptcha/api/siteverify?secret='
. $secret_key . '&response=' . $g_recaptcha_response;
// Get JSON response.
$google_json = file_get_contents($google);
$google_data = json_decode($google_json, true);
if ($google_data['success']) {
echo 'Hello human, this is your message: ' . $msg;
} else {
echo 'Robot detected! Error codes: ';
print_r($google_data['error-codes']);
}
echo '<hr />';
}
?>
<form method="post">
Your message: <input type="text" name="msg" />
<script src='https://www.google.com/recaptcha/api.js'></script>
<div class="g-recaptcha"
data-sitekey="6Lcvq8gSAAAAABTXeNtu2TSUKDeL90VqBODLcc2b">
</div>
<input type="submit" value="Submit" />
</form>
</body>
</html>
I also made authentication library using "No Captcha" so check it out here: http://zoran87.blogspot.com/2014/12/zorauth-10b-complete-flexible-no.html
