CAESAR(6)                  OpenBSD Reference Manual                  CAESAR(6)

NAME
     caesar, rot13 - decrypt caesar cyphers

SYNOPSIS
     caesar [rotation]
     rot13

DESCRIPTION
     The caesar utility attempts to decrypt caesar cyphers using English
     letter frequency statistics.  caesar reads from the standard input and
     writes to the standard output.

     The optional numerical argument rotation may be used to specify a
     specific rotation value.

     If this utility is invoked as rot13, it will rotate by 13 characters.
     This format is commonly used on USENET and in some of the databases used
     by the fortune(6) program to ``disguise'' their content.

     The frequency (from most common to least) of English letters is as
     follows:

           ETAONRISHDLFCMUGPYWBVKXJQZ

     Their frequencies as a percentage are as follows:

           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).

OpenBSD 4.9                      May 31, 2007                      OpenBSD 4.9