Sorted out rough flow of ch1

book/source/01-intro.md

@@ -1,37 +1,36 @@
-# OpenPGP: what is it, history
+# Notes on OpenPGP
 
-This document is intended as an introduction to the inner workings of OpenPGP,
+An introduction to the concepts of OpenPGP, aimed mainly at software
-aimed mainly at technical readers.
+developers who are looking to use OpenPGP functionality in their projects.
 
-It is *not* a guide for *use* of OpenPGP by end-users.
+This document describes
+[OpenPGP version 6](https://datatracker.ietf.org/doc/draft-ietf-openpgp-crypto-refresh/),
+with occasional remarks about differences to earlier versions.
+
+This text is *not* intended as a guide for end-users who use OpenPGP-related software.
 
 ## What is OpenPGP?
 
-OpenPGP is an open standard that was developed based on the
+OpenPGP is an open standard for cryptographic operations.
+It has grown out of the
 ["Pretty Good Privacy (PGP)"](https://en.wikipedia.org/wiki/Pretty_Good_Privacy)
 software.
 
-The standard has evolved over time, and there is ongoing work to improve it.
+OpenPGP is an open standard, there are many widely used
-[RFC 4880](https://datatracker.ietf.org/doc/html/rfc4880) is the most recent
+(and [interoperable](https://tests.sequoia-pgp.org/)) implementations.
-published version of the standard (describing OpenPGP version 4).
 
-An IETF working group is currently finalizing a
+## A very brief history
-[new revision](https://datatracker.ietf.org/doc/draft-ietf-openpgp-crypto-refresh/),
-of the OpenPGP standard (which will describe OpenPGP version 6).
-The current standardization work focuses on updating the cryptographic
-mechanisms in OpenPGP.
 
-There are multiple [interoperable](https://tests.sequoia-pgp.org/)
+The OpenPGP standard has evolved over time.
-implementations with significant use.
 
-## A very brief history (dramatis personae)
+(Also see https://www.openpgp.org/about/history/)
 
-### PGP
+### "Pretty Good Privacy (PGP)"
 
-*"Pretty Good Privacy (PGP)"* is a software program, initially by Phil
+The earliest roots of OpenPGP trace back to *"Pretty Good Privacy (PGP)"*,
-Zimmermann, first released in 1991.
+a software program, written by Phil Zimmermann and first released in 1991.
 
-The PGP software has played a role in the political struggles sometimes
+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).
@@ -45,38 +44,48 @@ The software enjoys a continued existence, albeit with
 [changing name and scope](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#PGP_Corporation_encryption_applications).
 
 
-### OpenPGP
+### Standardizing OpenPGP
 
 While the 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.
 The resulting open standard was named
 [OpenPGP](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#OpenPGP).
 
-The result of this first round of standardization work under the "OpenPGP"
+The result of this early standardization work is
-name is [RFC 2440](https://datatracker.ietf.org/doc/html/rfc2440),
+[RFC 2440 "OpenPGP Message Format"](https://datatracker.ietf.org/doc/html/rfc2440),
 published November 1998.
 
 The name "OpenPGP" can be used freely by implementations (unlike the name
 "PGP", which is a [registered trademark](https://uspto.report/TM/74685229)).
 
-### GnuPG
+### GnuPG, a free software implementation
 
 [First released 1997-12-20](https://gnupg.org/download/release_notes.html#sec-2-70),
 GnuPG is an implementation of the OpenPGP standard.
 
 GnuPG has been the major Free Software implementation of OpenPGP for a period
-of time. It has played a role in the release of NSA documents by
+of time. It has played an important and successful role in the release of NSA
-[Edward Snowden](https://theintercept.com/2014/10/28/smuggling-snowden-secrets/)
+documents by [Edward Snowden](https://theintercept.com/2014/10/28/smuggling-snowden-secrets/).
 
-## Multiple major implementations
+## The present
+
+### Multiple major implementations
 
 Today, multiple implementations of OpenPGP play an important role:
 
-- Protonmail, who serve a large number of users, use (and maintain)
+- Protonmail, who provide email encryption services for a large number of users,
-[OpenPGP.js](https://openpgpjs.org/).
+  use (and maintain) [OpenPGP.js](https://openpgpjs.org/).
 - 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).
+  implementation for their built-in OpenPGP support since version 78 (released in mid-2020).
 - The RPM Package Manager software includes an OpenPGP backend based on
-[Sequoia PGP](https://sequoia-pgp.org/), a modern OpenPGP implementation in Rust.
+  [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/)
+  Fedora [uses Sequoia PGP in rpm](https://sequoia-pgp.org/blog/2023/04/27/rpm-sequoia/)
-since version 38.
+  since version 38.
+
+### OpenPGP version 6
+
+This document mainly describes OpenPGP version 6, which brings many updates of the core cryptographic mechanisms,
+compared to the previous version 4.
+
+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).