BKCRPTAN.RVW   20091015

"Cryptanalysis", Helen Fouche Gaines, 1939, 978-0-486-20097-2,
U$9.95/C$14.95
%A   Helen Fouche Gaines
%C   31 E. 2nd St, Mineola, NY   11501
%D   1939
%G   978-0-486-20097-2 0-486-20097-3
%I   Dover Publications, Inc
%O   U$9.95/C$14.95 www.doverpublications.com
%O  http://www.amazon.com/exec/obidos/ASIN/0486200973/robsladesinterne
  http://www.amazon.co.uk/exec/obidos/ASIN/0486200973/robsladesinte-21
%O   http://www.amazon.ca/exec/obidos/ASIN/0486200973/robsladesin03-20
%O   Audience i+ Tech 3 Writing 2 (see revfaq.htm for explanation)
%P   237 p.
%T   "Cryptanalysis: A Study of Ciphers and Their Solution"

Written in 1939, and republished since, this work does not, of course,
address modern cryptography and algorithms.  It is primarily valuable
as an interesting guide to some of the history of cryptography.  It
also provides some general conceptual points, and gives practical
examples of the basic operations and principles of cryptanalysis. 
Cracking modern algorithms is complicated, mathematically intensive,
and tutorially impractical, but it does use the same ideas and
approaches which are addressed in a more accessible fashion here.

Chapter one is a general introduction to the ciphers, codes, and the
requirements which existed at the time the work was written.  Some of
the subsequent chapters, such as those on concealment and general
transposition ciphers, are also basic introductions, and therefore of
little use to a modern professional, although probably of greater
interest to hobbyists.  Once Gaines gets into specific ciphers (for
example Nihilist Transposition, in chapter four) she also starts
delivering detailed procedures for breaking the encryption, and
recovering both plaintext and keys.  Following the procedures requires
some application, but her explanation of (for example) the strip
piecing attack against columnar transposition is much clearer than
that given by David Kahn in "Codebreakers" (cf. BKCDBRKS.RVW): even
though Kahn considered himself a cryptanalyst, he never matched the
level of exegesis that Gaines provides.  (Not all of the material is
from Gaines herself: she also includes essays and exercises from
members of the American Cryptogram Society.)  The decryption of
substitution ciphers is often the more complex exercise, turning on a
combination of frequency analysis and guessing at probable words.

While this work will be of limited help in understanding modern
complex ciphers, the fundamental concepts illustrated may be of some
use.  More interesting are the examples of the convoluted ways that
people have tried to hide their information over the years--and the
equally ornate means others evolved in order to break those codes.

copyright Robert M. Slade, 2010    BKCRPTAN.RVW   20091015