verify and recover

[Oguz Yarimtepe]

I want to verify and recover a binary to its original version. It is
normally done via gpg as

gpg -s somefile

gpg --verify somefile.gpg

gpg -d somefile.gpg

By assuming that i have the somefile.gpg which functions i can use to
manage this issue?

I tried gpgme_op_decrypt_verify but it seems there should be an
encrypted data. gpgme_op_verify may be achieve this but i am not so sure
how to use it.