mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-20 11:11:24 +00:00
80 lines
2.9 KiB
Groff
80 lines
2.9 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)caesar.6 8.2 (Berkeley) 11/16/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd November 16, 1993
|
|
.Dt CAESAR 6
|
|
.Os
|
|
.Sh NAME
|
|
.Nm caesar , rot13
|
|
.Nd decrypt caesar ciphers
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Op Ar rotation
|
|
.Nm rot13
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
utility attempts to decrypt caesar ciphers using English letter frequency
|
|
statistics.
|
|
.Nm Caesar
|
|
reads from the standard input and writes to the standard output.
|
|
.Pp
|
|
The optional numerical argument
|
|
.Ar rotation
|
|
may be used to specify a specific rotation value.
|
|
If invoked as
|
|
.Nm rot13 ,
|
|
a rotation value of 13 will be used.
|
|
.Pp
|
|
The frequency (from most common to least) of English letters is as follows:
|
|
.Pp
|
|
.Bd -ragged -offset indent
|
|
ETAONRISHDLFCMUGPYWBVKXJQZ
|
|
.Ed
|
|
.Pp
|
|
Their frequencies as a percentage are as follows:
|
|
.Pp
|
|
.Bd -ragged -offset indent
|
|
E(13), T(10.5), A(8.1), O(7.9), N(7.1), R(6.8), I(6.3), S(6.1), H(5.2),
|
|
D(3.8), L(3.4), F(2.9), C(2.7), M(2.5), U(2.4), G(2),
|
|
P(1.9), Y(1.9),
|
|
W(1.5), B(1.4), V(.9), K(.4), X(.15), J(.13), Q(.11), Z(.07).
|
|
.Ed
|
|
.Pp
|
|
Rotated postings to
|
|
.Tn USENET
|
|
and some of the databases used by the
|
|
.Xr fortune 6
|
|
program are rotated by 13 characters.
|