'<?php
$msg=file_get_contents('enes.jpg');
//echo $msg;
$key = "bRuD5WYw5wd0rdHR9yLlM6wt2vteuiniQBqE70nAuhU=";
$msg_encrypted = my_encrypt($msg, $key);
//$msg_encrypted = my_decrypt($msg, $key);
$file = fopen("enes.jpg", "wb");
fwrite($file, $msg_encrypted);
fclose($file);

function my_encrypt($data, $key) {

$encryption_key = base64_decode($key);
$iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length("aes-256-cbc"));
$encrypted = openssl_encrypt($data, "aes-256-cbc", $encryption_key, 0, $iv);
return base64_encode($encrypted . '::' . $iv);

}

function my_decrypt($data, $key) {

$encryption_key = base64_decode($key);
list($encrypted_data, $iv) = explode("::", base64_decode($data), 2);
return openssl_decrypt($encrypted_data, "aes-256-cbc", $encryption_key, 0, $iv);

}
?>'
Yukarıdaki şekilde işimi hallettim. Belki başka arkadaşlarında işine yarar diye cevabı paylaşıyorum.