OpenPGP for application developers

A new book called OpenPGP for application
developers has been released under the Creative Commons BY-SA license.

This document is not intended for end-users or implementers of
OpenPGP libraries (or other software that directly handles internal
OpenPGP data structures).

Instead, this document is focused on the second group, application
developers, who use OpenPGP functionality in their software
projects. It describes the properties of the OpenPGP system and its
uses. It presupposes solid knowledge of software development
concepts and of general cryptographic concepts. Thus, this text
describes OpenPGP at the “library-level,” teaching concepts that
will help software developers get started as a user of any
implementation (e.g., OpenPGP.js, Sequoia-PGP).