how to use php call linux GPG encrypt file with a passphase

I have a task which need to

use gpg to encrypt the upload file in php

my code is:

("echo '1234' | gpg --passphrase-fd 0 -c /path/aaa.jpg ");开发者_如何学运维

it works by paste the code in linux

but not work by php any solution

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You need to use gnupg_decypt() to decrypt the text.