OpenPGP is the most widely used email encryption standard in the world. It is defined by the OpenPGP Working Group of the Internet Engineering Task Force (IETF) Proposed Standard RFC 9580. The OpenPGP standard was originally derived from PGP (Pretty Good Privacy), first created by Phil Zimmermann in 1991.

OpenPGP is not just used for email encryption however, but also for encryption and verifying the authenticity and integrity of files and for authentication. The most commonly used software for working with OpenPGP in Debian is GnuPG. There are also many software packages that use GnuPG in their backend to provide cryptographic features, and alternatives to GnuPG such as netpgp (wnpp) also exist.

OpenPGP-compatible Software in Debian

There's an OpenPGP interoperability test suite.

GnuPG

GnuPG is a complete and free implementation of the OpenPGP standard. GnuPG allows to encrypt and sign your data and communication, features a versatile key management system as well as access modules for all kinds of public key directories. GnuPG, also known as GPG, is a command line tool with features for easy integration with other applications. A wealth of frontend applications and libraries are available. Version 2 of GnuPG also provides support for S/MIME and Secure Shell (ssh).

More information about GnuPG can be found on its dedicated wiki page.

Stateless OpenPGP (SOP) interface

This is an IETF draft to document a stateless OpenPGP command-line interface.

Several OpenPGP implementations provide such native interfaces, while others have been created by the Sequoia-PGP team. In Debian, the sqop package provides one such interface.

Other Software

Upstream Name	Package(s)	Lang	Description
sq	sq	Rust	Command-line interface for Sequoia-PGP
sq-keyring-linter	sq-keyring-linter	Rust	Sequoia keyring linter and fixer tool
sqv	sqv	Rust	Sequoia command-line verification tool
sqop	sqop	Rust	Sequoia SOP implementation
PGPainless	pgpainless-cli	Java	PGPainless SOP implementation
GopenPGP	golang-github-protonmail-gopenpgp-dev	Go	high-level OpenPGP library
gosop	gosop	Go	GopenPGP SOP implementation
python-sop	python3-sop	Python	Framework for implementing the SOP CLI
hOpenPGP	libghc-hopenpgp-dev	Haskell	OpenPGP library
hopenpgp-tools	hopenpgp-tools	Haskell	OpenPGP tools built using hOpenPGP, including a SOP implementation
monkeysign	monkeysign	?	OpenPGP key signing and exchange for humans
monkeysphere	monkeysphere	?	leverage the OpenPGP web of trust for SSH and TLS authentication
onak	onak	C	OpenPGP Key Server
parcimonie	parcimonie	Perl	privacy-friendly helper to refresh a GnuPG keyring
RNP	rnp	C++	OpenPGP library and command-line tools
Seahorse	seahorse	C	GNOME front end for GnuPG

Note: This list is incomplete, help in completing it is appreciated.

Usage by the Debian Project

When joining the Debian project, developers need to identify themselves by providing an OpenPGP key that is signed by at least two existing members of the project. Contributions to the Debian archive are cryptographically signed using the developer's OpenPGP key to protect against forgeries.

The Debian Keyring and other keyrings maintained by keyring-maint are the keyrings that contain those OpenPGP keys which belong to Debian Developers (uploading and non-uploading) and Debian Maintainers.

It is suggested to use a Clean Room environment, such as a Live CD to manage OpenPGP private keys.

There are some best practices for OpenPGP available.

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