1*28472285Sjmc.\" $OpenBSD: caesar.6,v 1.10 2024/08/26 20:12:33 jmc Exp $ 2df930be7Sderaadt.\" 3df930be7Sderaadt.\" Copyright (c) 1989, 1991, 1993 4df930be7Sderaadt.\" The Regents of the University of California. All rights reserved. 5df930be7Sderaadt.\" 6df930be7Sderaadt.\" Redistribution and use in source and binary forms, with or without 7df930be7Sderaadt.\" modification, are permitted provided that the following conditions 8df930be7Sderaadt.\" are met: 9df930be7Sderaadt.\" 1. Redistributions of source code must retain the above copyright 10df930be7Sderaadt.\" notice, this list of conditions and the following disclaimer. 11df930be7Sderaadt.\" 2. Redistributions in binary form must reproduce the above copyright 12df930be7Sderaadt.\" notice, this list of conditions and the following disclaimer in the 13df930be7Sderaadt.\" documentation and/or other materials provided with the distribution. 147a09557bSmillert.\" 3. Neither the name of the University nor the names of its contributors 15df930be7Sderaadt.\" may be used to endorse or promote products derived from this software 16df930be7Sderaadt.\" without specific prior written permission. 17df930be7Sderaadt.\" 18df930be7Sderaadt.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19df930be7Sderaadt.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20df930be7Sderaadt.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21df930be7Sderaadt.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22df930be7Sderaadt.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23df930be7Sderaadt.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24df930be7Sderaadt.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25df930be7Sderaadt.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26df930be7Sderaadt.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27df930be7Sderaadt.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28df930be7Sderaadt.\" SUCH DAMAGE. 29df930be7Sderaadt.\" 30df930be7Sderaadt.\" @(#)caesar.6 8.2 (Berkeley) 11/16/93 31df930be7Sderaadt.\" 32*28472285Sjmc.Dd $Mdocdate: August 26 2024 $ 33df930be7Sderaadt.Dt CAESAR 6 34df930be7Sderaadt.Os 35df930be7Sderaadt.Sh NAME 36ff6fd72cSjmc.Nm caesar , 37ff6fd72cSjmc.Nm rot13 38df930be7Sderaadt.Nd decrypt caesar cyphers 39df930be7Sderaadt.Sh SYNOPSIS 40a702fa09Spjanzen.Nm caesar 41df930be7Sderaadt.Op Ar rotation 42ff6fd72cSjmc.Nm rot13 43df930be7Sderaadt.Sh DESCRIPTION 44df930be7SderaadtThe 455dc4a87cSpjanzen.Nm 46df930be7Sderaadtutility attempts to decrypt caesar cyphers using English letter frequency 47df930be7Sderaadtstatistics. 483897dfeeSpjanzen.Nm 49df930be7Sderaadtreads from the standard input and writes to the standard output. 50df930be7Sderaadt.Pp 51df930be7SderaadtThe optional numerical argument 52df930be7Sderaadt.Ar rotation 53df930be7Sderaadtmay be used to specify a specific rotation value. 54df930be7Sderaadt.Pp 55ff6fd72cSjmcIf this utility is invoked as 56ff6fd72cSjmc.Nm rot13 , 57ff6fd72cSjmcit will rotate by 13 characters. 5812bc6069SschwarzeThis format is commonly used on USENET 59*28472285Sjmcto 60ff6fd72cSjmc.Dq disguise 61*28472285Sjmccontent. 62df930be7Sderaadt.Pp 63ff6fd72cSjmcThe frequency (from most common to least) of English letters is as follows: 64df930be7Sderaadt.Bd -filled -offset indent 65df930be7SderaadtETAONRISHDLFCMUGPYWBVKXJQZ 66df930be7Sderaadt.Ed 67df930be7Sderaadt.Pp 68df930be7SderaadtTheir frequencies as a percentage are as follows: 69df930be7Sderaadt.Bd -filled -offset indent 70df930be7SderaadtE(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), 71df930be7SderaadtD(3.8), L(3.4), F(2.9), C(2.7), M(2.5), U(2.4), G(2), 72df930be7SderaadtP(1.9), Y(1.9), 73df930be7SderaadtW(1.5), B(1.4), V(.9), K(.4), X(.15), J(.13), Q(.11), Z(.07). 74df930be7Sderaadt.Ed 75