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* lisp/rot13.el: Improve documentation. (Bug#47970)

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Stefan Kangas 2021-04-24 10:47:50 +02:00
parent 72ac446167
commit ae81b9503a
1 changed files with 19 additions and 10 deletions
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29
lisp/rot13.el
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@ -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: