Signal/Whatsapp/etc that use the Signal Protocal are this for messaging.
It turns out solving one problem at a time and ending up with a bunch of purpose-built tools is way easier to get right than trying to jam an entire toolbox into one thing.
>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).
It's used by quite a few companies and public administrations.