encrypter.php

<?php
// ... some code ...

$fileStream = fopen($file, "r");
$encFileStream = fopen($file . ".enc.data", "w");

$opts = [
    'iv' => $iv,
    'key' => $key,
    'mode' => 'cbc'
];

fwrite($encFileStream, hex2bin('006D0300'));
fwrite($encFileStream, $iv);

stream_filter_append($encFileStream, 'mcrypt.rijndael-256', STREAM_FILTER_WRITE, $opts);
stream_copy_to_stream($fileStream, $encFileStream);

fclose($fileStream);
fclose($encFileStream);