usr/src/games/caesar/caesar.6

.\" Copyright (c) 1989, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)caesar.6    5.4 (Berkeley) %G%
.\"
.Dd
.Dt CAESAR 6
.Os
.Sh NAME
.Nm caesar
.Nd decrypt caesar cyphers
.Sh SYNOPSIS
.Nm caesar
.Op Ar rotation
.Sh DESCRIPTION
The
Nm caesar
utility attempts to decrypt caesar cyphers 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.
.Pp
The frequency (from most common to least) of English letters is as follows:
.Pp
.Bd -filled -offset indent
ETAONRISHDLFCMUGPYWBVKXJQZ
.Ed
.Pp
Their frequencies as a percentage are as follows:
.Pp
.Bd -filled -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.