Demo Captcha

<?php
    // EDIT THIS: Insert secret and site key from Google https://www.google.com/recaptcha/admin#list
    $googleRecaptchaSecret = '6L...';
    $googleSiteKey         = '6J...';
?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Google reCaptha Demo</title>
    <script src='https://www.google.com/recaptcha/api.js'></script>
    <style>
    <!--
        body {
            font-family: Helvetica;
            font-size: 1.2em;
        }
        td {
            padding: 8px;
        }
        h1 {
            color: white;
            padding: 9px;
            border-radius: 8px;
            background-color: #C9A;
        }
        form {
            background-color: #EDC;
            border-radius: 8px;
            padding: 9px;
        }
        .ok { color: green; }
        .ko { color: red;}
    -->
    </style>
</head>
<body>
<h1>Google <em>re</em>Captha Demo</h1>
<?php
    // Get form parameters
    $input = $_REQUEST['input1'];
    $captcha = $_REQUEST['g-recaptcha-response'];
    $response=json_decode(file_get_contents("https://www.google.com/recaptcha/api/siteverify?secret=" . $googleRecaptchaSecret .
            "&response=".$captcha."&remoteip=".$_SERVER['REMOTE_ADDR']), true);
    if (isset($input)) {
        if ($response['success']) {
            print '<h2 class="ok">reCaptha has been validated!</h2>';
        } else {
            print '<h2 class="ko">reCaptha has not been validated!</h2>';
        }
        print "<h3>Data received  (\$_REQUEST)</h3><pre>";
        print_r($_REQUEST);
        print "\n</pre>
        <h3>Response from Google</h3><pre>\n";
        print_r($response);
        print "</pre>\n";
    }
?>

<form action="?">
<!-- Hidden Fields -->

<table>
    <tr>
        <td>Sample Input field:</td>
        <td><input name="input1"></td>
    </tr>
    <tr>
        <td colspan="2">
        <div class="g-recaptcha" data-callback="enableBtn" data-sitekey="<?php echo $googleSiteKey; ?>"></div>
        </td>
    </tr>

    <tr>
        <td></td>
        <td><input type="submit" id="buttonSubmit"></td>
    </tr>

</table>
</form>

<script>
// disable submit button until user clicks "I'm not a robot"
document.getElementById("buttonSubmit").disabled = true;
function enableBtn(){
    document.getElementById("buttonSubmit").disabled = false;
}
</script>

</body>
</html>