GopenPGP, an open source encryption library for native applications

First, we believe more people should have access to encrypted communications, and an easy-to-use encryption library for mobile developers is an important step forward in that mission. Second, the release of GopenPGP paves the way to open sourcing the ProtonMail mobile and desktop apps, which has been a high priority for our team and for our users (our web app has already been open sourced since 2015). GopenPGP (a portmanteau of Go and OpenPGP) is a high-level OpenPGP library that we have developed for use in our own Android and iOS, Bridge, and Import-Export apps, as well as a fork of the golang crypto library, which the high-level library is built on.

Source: protonmail.com