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Veronica's Decryption Demonstration

CODE FOLLOWS

<?php



include('includes/header.php');



// set error reporting to all

error_reporting(E_ALL);

$self = basename($_SERVER['SCRIPT_NAME']);



$encrypted = isset($_POST['encrypted']) ? $_POST['encrypted'] : "";



$action = 'decrypt';

$decrypted = encrypt_decrypt($action, $encrypted);



?>



<h1> Veronica's Decryption Demonstration</h1>



<form action="<?php echo($self); ?>" method="POST">



    <fieldset>

        <legend>Encrypted String</legend>



        <textarea rows="10" cols="120" type="text" name="encrypted" value="<?php echo($encrypted); ?>">

<?php echo($encrypted); ?>

</textarea>

        <br>

    </fieldset>



    <br> <br>



    <fieldset>

        <legend>Decrypted String</legend>

        <textarea rows="10" cols="120" type="text" name="decrypted" value="">

<?php echo($decrypted); ?>

</textarea>

        <br>

    </fieldset>



    <p>

        <input type="submit" name="submit" value="Decrypt">

    </p>



</form>



<a href="encrypt_form.php">GOTO Encrypt</a>



<?php



// ======== functions ============



function encrypt_decrypt($action, $string)

{



    $output = false;

    $encrypt_method = "AES-256-CBC";



    // the following two values should be changed for your personal use.

//    $secret_key = 'Epur si muove';

    $secret_key = 'clavis abscondita';

//    $secret_iv = 'non sum qualis eram';

    $secret_iv = 'nuntius mutans';



    // hash

    $key = hash('sha256', $secret_key);



    // encrypt method AES-256-CBC expects 16 bytes.

    $iv = substr(hash('sha256', $secret_iv), 0, 16);



    if ($action == 'encrypt')

    {

        $output = base64_encode(openssl_encrypt($string, $encrypt_method, $key, 0, $iv));

    }

    else

    {

        if ($action == 'decrypt')

        {

            $output = openssl_decrypt(base64_decode($string), $encrypt_method, $key, 0, $iv);

        }

    }

    return $output;

}



include('includes/footer.php');



?>
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