NAME
caesar, rot13
— decrypt caesar
ciphers
SYNOPSIS
caesar |
[rotation] |
rot13 |
DESCRIPTION
Thecaesar utility attempts to decrypt caesar ciphers
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 invoked as
rot13, a rotation value of 13 will be used.
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).
Rotated postings to USENET and some of the databases used by the fortune(6) program are rotated by 13 characters.