CAESAR(6)

NAME

     caesar, rot13 -- decrypt caesar ciphers

SYNOPSIS

     caesar [rotation]
     rot13

DESCRIPTION

     The caesar utility attempts to decrypt caesar ciphers using English let-
     ter 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 spe-
     cific 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 fol-
     lows:

	   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.