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83 lines
3.4 KiB
Markdown
83 lines
3.4 KiB
Markdown
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# OpenPGP: what is it, history
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This document is intended as an introduction to the inner workings of OpenPGP,
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aimed mainly at technical readers.
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It is *not* a guide for *use* of OpenPGP by end-users.
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## What is OpenPGP?
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OpenPGP is an open standard that was developed based on the
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["Pretty Good Privacy (PGP)"](https://en.wikipedia.org/wiki/Pretty_Good_Privacy)
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software.
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The standard has evolved over time, and there is ongoing work to improve it.
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[RFC 4880](https://datatracker.ietf.org/doc/html/rfc4880) is the most recent
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published version of the standard (describing OpenPGP version 4).
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An IETF working group is currently finalizing a
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[new revision](https://datatracker.ietf.org/doc/draft-ietf-openpgp-crypto-refresh/),
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of the OpenPGP standard (which will describe OpenPGP version 6).
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The current standardization work focuses on updating the cryptographic
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mechanisms in OpenPGP.
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There are multiple [interoperable](https://tests.sequoia-pgp.org/)
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implementations with significant use.
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## A very brief history (dramatis personae)
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### PGP
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*"Pretty Good Privacy (PGP)"* is a software program, initially by Phil
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Zimmermann, first released in 1991.
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The PGP software has played a role in the political struggles sometimes
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referred to as the ["Crypto Wars"](https://en.wikipedia.org/wiki/Crypto_Wars)
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(also see https://en.wikipedia.org/wiki/Crypto_(book) for some of that history,
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including about the history of PGP).
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The "PGP" software was never under a Free Software license,
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even though its source code has at one point been widely published.
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The ownership and branding of the product has
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[changed over the years](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#PGP_Corporation_and_Symantec),
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The software enjoys a continued existence, albeit with
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[changing name and scope](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#PGP_Corporation_encryption_applications).
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### OpenPGP
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While the PGP software was developed as a commercial product, the owner at the time,
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"PGP Inc." started a standardization effort with the IETF in July 1997.
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The resulting open standard was named
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[OpenPGP](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#OpenPGP).
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The result of this first round of standardization work under the "OpenPGP"
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name is [RFC 2440](https://datatracker.ietf.org/doc/html/rfc2440),
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published November 1998.
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The name "OpenPGP" can be used freely by implementations (unlike the name
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"PGP", which is a [registered trademark](https://uspto.report/TM/74685229)).
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### GnuPG
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[First released 1997-12-20](https://gnupg.org/download/release_notes.html#sec-2-70),
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GnuPG is an implementation of the OpenPGP standard.
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GnuPG has been the major Free Software implementation of OpenPGP for a period
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of time. It has played a role in the release of NSA documents by
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[Edward Snowden](https://theintercept.com/2014/10/28/smuggling-snowden-secrets/)
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## Multiple major implementations
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Today, multiple implementations of OpenPGP play an important role:
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- Protonmail, who serve a large number of users, use (and maintain)
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[OpenPGP.js](https://openpgpjs.org/).
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- The Thunderbird email software is using the [RNP](https://www.rnpgp.org/)
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implementation for their built-in OpenPGP support since version 78 (released in mid-2020).
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- The RPM Package Manager software includes an OpenPGP backend based on
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[Sequoia PGP](https://sequoia-pgp.org/), a modern OpenPGP implementation in Rust.
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Fedora [uses Sequoia PGP in rpm](https://sequoia-pgp.org/blog/2023/04/27/rpm-sequoia/)
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since version 38.
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