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70 lines
No EOL
3.8 KiB
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# A high-level view
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## A very brief history
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The OpenPGP standard has evolved over time, and remains under active development.
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(Also see https://www.openpgp.org/about/history/)
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### "Pretty Good Privacy (PGP)"
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The earliest roots of OpenPGP trace back to *"Pretty Good Privacy (PGP)"*, a software program written by [Phil Zimmermann](https://en.wikipedia.org/wiki/Phil_Zimmermann) and first released in 1991.
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The original PGP software has played a role in the political struggles sometimes referred to as the ["Crypto Wars"](https://en.wikipedia.org/wiki/Crypto_Wars) (also see https://en.wikipedia.org/wiki/Crypto_(book) for some of that history, including about the history of PGP).
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The original "PGP" software was never under a Free Software license, even though its source code has at one point been widely published.
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The ownership and branding of the product has [changed over the years](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#PGP_Corporation_and_Symantec). The software enjoys a continued existence, albeit with [changing name and scope](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#PGP_Corporation_encryption_applications).
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### Standardizing OpenPGP
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While the original PGP software was developed as a commercial product, the owner at the time, "PGP Inc." started a standardization effort with the IETF in July 1997.
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The resulting open standard was named [OpenPGP](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#OpenPGP).
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The result of this early standardization work is [RFC 2440 "OpenPGP Message Format"](https://datatracker.ietf.org/doc/html/rfc2440), published November 1998. RFC 2440 describes OpenPGP version 3.
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The name "OpenPGP" can be used freely by implementations (unlike the name "PGP", which is a [registered trademark](https://uspto.report/TM/74685229)).
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### GnuPG, a free software implementation
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[First released 1997-12-20](https://gnupg.org/download/release_notes.html#sec-2-70), 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 of time. It has played an important (and successful) role in the release of NSA documents by [Edward Snowden](https://theintercept.com/2014/10/28/smuggling-snowden-secrets/).
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## The present
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### Multiple major implementations
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Today multiple new Free Software implementations of OpenPGP play important roles:
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- Protonmail, who provide email encryption services for a large number of users, use (and maintain) [OpenPGP.js](https://openpgpjs.org/)as well as [GopenPGP](https://gopenpgp.org/).
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- The Thunderbird email software is using the [RNP](https://www.rnpgp.org/) 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 [Sequoia PGP](https://sequoia-pgp.org/), a modern OpenPGP implementation in Rust. Fedora [uses Sequoia PGP in rpm](https://sequoia-pgp.org/blog/2023/04/27/rpm-sequoia/) since version 38.
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### OpenPGP version 6
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This document mainly describes OpenPGP version 6, which brings many updates of the core cryptographic mechanisms, compared to the previous version 4.
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As of this writing (in 2023), version 4 of OpenPGP is still most commonly used. OpenPGP version 4 is described in [RFC 4880](https://datatracker.ietf.org/doc/html/rfc4880).
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## Concepts
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### Certificates/Keys
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All uses of OpenPGP are centered around (asymmetric) cryptographic key material. In OpenPGP, cryptographic keys are combined with additional metadata into "OpenPGP Keys", or "OpenPGP Certificates".
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See chapter "certs" (link) for more on OpenPGP Certificates, and "private" for handling of private key material in OpenPGP.
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### Cryptographic operations
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- Signatures
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- Encryption
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### Internal structure of OpenPGP data
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OpenPGP data is structured as "packets" (and sometimes "subpackets"), internally.
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## Interoperability
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```describe, and link to interop test suite``` |