There's a library wrapper, https://www.gnupg.org/software/gpgme/index.html

>GnuPG Made Easy (GPGME) is a library designed to make access to GnuPG easier for applications. It provides a High-Level Crypto API for encryption, decryption, signing, signature verification and key management. Currently it uses GnuPG's OpenPGP backend as the default, but the API isn't restricted to this engine. We have, in fact, already developed a backend for CMS (S/MIME).