<!doctype html>
<html>
<head></head>
<body> 

<?php
require_once ('tokenkonfiguration.php');

if(isset($_GET['token'])  ) {

// E-Mail-Adresse des Nutzers
$encrypted_data = $_GET['token'];
$encrypted_iv = $_GET['iv'];
echo "token: $encrypted_data<br> \n";
echo "iv:    $encrypted_iv<br> \n";

// Erstellen eines Cipher-Objekts für die Verschlüsselung
$cipher_method = "AES-256-CBC";
$iv_length = openssl_cipher_iv_length($cipher_method);
$iv = base64_decode($encrypted_iv);
$cipher_options = OPENSSL_RAW_DATA;
$cipher_key = openssl_digest($secret_key, 'SHA256', true);

// Entschlüsseln des verschlüsselten Textes
$decoded_cipher_text = base64_decode($encrypted_data);
$iv = base64_decode($encrypted_iv);
$iv = substr($decoded_cipher_text, 0, $iv_length);
$cipher_text = substr($decoded_cipher_text, $iv_length);
$decrypted_email = openssl_decrypt($cipher_text, $cipher_method, $cipher_key, $cipher_options, $iv);

// Verifikationsstring überprüfen und entfernen
$verification_length = strlen($secret_verification);
if(substr($decrypted_email, -$verification_length) == $secret_verification) {
    $decrypted_email = substr($decrypted_email, 0, -$verification_length);
}

// Ausgabe der entschlüsselten E-Mail-Adresse
echo "E-Mail-Adresse: ", $decrypted_email, "<br>\n";

} else {

echo "Kein g&uuml;ltiges Token!<br>";
}

?>
</body></html>
