Can not encrypt & decrypt JPG file

[poul-kg]

I want to encrypt and then decrypt .jpg file

Here is the code snippet I use:

$crypter = new MCrypt();
// encrypt
file_put_contents('dst.ejp', $crypter->encrypt(file_get_contents('src.jpg')));
// decrypt
file_put_contents('dst-decrypted.jpg', $crypter->decrypt(file_get_contents('dst.ejp')));

but the final dst-decrypted.jpg is not a valid image file anymore.

Any suggestions? I'm using PHP 5.4.20