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University of the Aegean, GR-83200 Karlovasi, Greece
Cryptology provides the foundations for information security and
privacy in our global internetworked society. Its subject area
covers cryptography and cryptanalysis, history and applications,
theory and practice. "Descrypted secrets" succeeds in
blending these ingredients in a readable and interesting mix.
The book, its content being about equally divided between cryptography
and cryptanalysis, can almost serve as a self-contained cryptology
The first half of the book contains an exposition of various encryption
methods. Many methods are illustrated by real-life historical
examples. The description of mechanical encryption devices such
as ENIGMA is particularly detailed. In a short section at the
end of the first part Bauer introduces a number of cryptology
maxims which provides an authoritative reference for a number
of cryptological principles that are often anecdotally presented.
The second half of the book covers cryptanalysis. Most methods
covered are based on linguistic properties of the cleartext.
Those of us who have read books detailing the historical events
surrounding the breaking of the ENIGMA codes during World War
II will be fascinated by a case-by-case description of the theory
and practice behind those efforts.
The most important asset of the book is that it really does cover
cryptanalysis. The author, using numerous examples, guides us
through increasingly sophisticated methods of cryptanalysis beginning
with exhaustive combinatorial searches and ending with periodicity
and alignment examinations. Although the theoretical foundations
of the methods covered are presented in full detail, readers who
are not mathematically inclined can skip the theorem proofs and
follow the detailed, step-by-step examples. Having been spoiled
by the increasingly clever cryptanalytic attacks of the cryptographic
methods presented in the first half of the book, I was - somewhat
naively of course - expecting to see modern cryptographic algorithms
like DES and IDEA be covered in a similar spirit. I was more
than disappointed. Apart from a description of possible cryptanalytic
attacks upon RSA and a brief mention of differential cryptanalysis
the cryptanalytic coverage of modern cipher systems is almost
Credit must go to the author and the publisher for producing a
truly beautiful book. The cover, binding, and typesetting are
superb. However, what clearly sets the book apart are the wonderful
and rare illustrations and colour plates of cipher texts, encryption
machines, and operating manuals. In addition, although lightly
covered, the policy debate on cryptography is refreshingly viewed
from a non US-centric perspective.
Despite the many commendable qualities of the book some minor
problems spoil its overall utility. The most important is the
almost total lack of references behind factual and theoretical
descriptions. The wealth of information presented in the book
would mean that references could easily double its size, but given
the scarcity of other resources they would be well worth the increase.
Although, most drawings are interesting and well reproduced,
the DES drawings could be better typeset and labelled in English.
Similarly, many fictitious examples could be phrased in English
instead of German. Cryptographic protocols, hash functions,
digital hardware, software, and digital signatures are very lightly
covered. Finally, the flow of text is not always smooth. Some
paragraphs abruptly begin explaining a theoretical concept without
any obvious leads.
"Decrypted Secrets" is a unique book. Covering in depth
all methods of historical interest it can act as a companion to
"The Codebreakers" (David Kahn, Scribner, 1996) providing
the theory behind Kahn's narrative exposition and can also provide
historical context and cryptanalytical background to Schneier's
"Applied Cryptography" (Bruce Schneier, Wiley, 1996).
According to Kerckhoffs's maxim that Bauer presents "only
a cryptanalyst can judge the security of a crypto system".
The combined wealth of cryptographic and cryptanalytic information
available in a single volume can guide us towards more secure
Decrypted Secrets: Methods and Maxims of Cryptology by Friedrich L. Bauer, Springer Verlag, Berlin, 1997, 448 pp., $39.95.