Email Encryption

<?php
$key = $_GET['key'];
$recipient = htmlspecialchars($_GET['recipient']);
$subject = htmlspecialchars($_GET['subject']);
$body = htmlspecialchars($_GET['body']);

$email = "<p class='recipient'>{$recipient}</p><p class='subject'>{$subject}</p><p class='message'>{$body}</p>";

$keyLength = strlen($key);
$encrypted = '';
for ($i = 0; $i < strlen($email); $i++) {
    $emailCharCode = ord($email[$i]);
    $keyCharCode = ord($key[($i % $keyLength)]);
    $encrypted .= '|' . dechex($emailCharCode * $keyCharCode);
}

echo $encrypted . '|';