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master ae81b95: * lisp/rot13.el: Improve documentation. (Bug#47970)
From: |
Stefan Kangas |
Subject: |
master ae81b95: * lisp/rot13.el: Improve documentation. (Bug#47970) |
Date: |
Sat, 24 Apr 2021 04:49:49 -0400 (EDT) |
branch: master
commit ae81b9503ac4af7d4e57ee81f3b953142d6fb015
Author: Stefan Kangas <stefan@marxist.se>
Commit: Stefan Kangas <stefan@marxist.se>
* lisp/rot13.el: Improve documentation. (Bug#47970)
---
lisp/rot13.el | 29 +++++++++++++++++++----------
1 file changed, 19 insertions(+), 10 deletions(-)
diff --git a/lisp/rot13.el b/lisp/rot13.el
index dfcf4ad..4e4e60f 100644
--- a/lisp/rot13.el
+++ b/lisp/rot13.el
@@ -3,6 +3,7 @@
;; Copyright (C) 1988, 2001-2021 Free Software Foundation, Inc.
;; Author: Howard Gayle
+;; Simon Josefsson
;; Maintainer: emacs-devel@gnu.org
;; This file is part of GNU Emacs.
@@ -22,18 +23,26 @@
;;; Commentary:
-;; The entry point, `rot13-other-window', performs a Caesar cipher
-;; encrypt/decrypt on the current buffer and displays the result in another
-;; window. ROT13 encryption is sometimes used on USENET as a read-at-your-
-;; own-risk wrapper for material some might consider offensive, such as
-;; ethnic humor.
+;; "ROT13 ('rotate by 13 places') is a simple letter substitution
+;; cipher that replaces a letter with the 13th letter after it in
+;; the alphabet. ROT13 is a special case of the Caesar cipher
+;; which was developed in ancient Rome.
;;
-;; Written by Howard Gayle.
-;; This hack is mainly to show off the char table stuff.
+;; Because there are 26 letters (2×13) in the basic Latin
+;; alphabet, ROT13 is its own inverse; that is, to undo ROT13, the
+;; same algorithm is applied, so the same action can be used for
+;; encoding and decoding. The algorithm provides virtually no
+;; cryptographic security, and is often cited as a canonical
+;; example of weak encryption.
;;
-;; New entry points, `rot13', `rot13-string', and `rot13-region' that
-;; performs Caesar cipher encrypt/decrypt on buffers and strings, was
-;; added by Simon Josefsson.
+;; ROT13 is used in online forums as a means of hiding spoilers,
+;; punchlines, puzzle solutions, and offensive materials from the
+;; casual glance." - Wikipedia article on ROT13
+;;
+;; The entry points, `rot13', `rot13-string', and `rot13-region' performs ROT13
+;; encoding/decoding on buffers and strings. The entry point
+;; `rot13-other-window' performs a ROT13 encoding/decoding on the current
+;; buffer and displays the result in another window.
;;; Code:
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