[ISN] REVIEW: "Decrypted Secrets"

From: mea culpa (jerichot_private)
Date: Fri Oct 16 1998 - 15:15:08 PDT

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    Forwarded From: darek milewski <darekmt_private>
    BKDECSEC.RVW   980804
    "Decrypted Secrets", F. L. Bauer, 1997, 3-540-60418-9, U$39.95
    %A   F. L. Bauer
    %C   175 Fifth Ave., New York, NY   10010
    %D   1997
    %G   3-540-60418-9
    %I   Springer-Verlag
    %O   U$39.95 212-460-1500 800-777-4643
    %P   447 p.
    %T   "Decrypted Secrets: Methods and Maxims of Cryptology"
    Cryptology is the study of the technologies of taking plain, readable
    text, turning it into an incomprehensible mishmash, and then recovering
    the initial information.  There are two sides to this study.  Cryptography
    is the part that lets you garble something, and then recover it if you
    have the key.  Cryptanalysis is usually seen as the "dark side" of the
    operation, because it is the attempt to get at the original meaning when
    you *don't* have the key.  Most current and popular works on cryptology
    actually only speak about cryptography.  For one thing, nobody wants to
    get into trouble by telling people how to break encryption.  However, it
    is also much easier to blithely talk about key lengths and algorithms and
    pretend to know what you are doing if you don't have to understand enough
    math to try to figure out how to go about cracking a particular cipher. 
    Bauer examines both sides, which is an important plus.  If you need to
    decide how strong an encryption algorithm or system is, it is important to
    know how difficult it might be to break it. 
    Chapter one looks at Steganography, the science of hiding in plain sight,
    or concealing the fact that a message exists at all.  In this he first
    demonstrates a wide ranging historical background which is quite
    fascinating in its own right.  Basic encryption concepts are introduced by
    the same historical background, but move on to a very dense mathematical
    discussion of cryptographic characteristics in chapter two.  Encryption
    functions are started in chapter three, and it is delightful to have
    examples other than Julius Caesar's substitution code.  Polygraphic
    substitutions are in chapter four and the math for advanced substitutions
    is in chapter five.  Chapter six introduces transpositions.  Families of
    alphabets, and rotor encryptors such as ENIGMA, are reviewed in chapter
    seven.  Keys are discussed in chapter eight, ending with a brief look at
    key management.  Chapter nine covers the combination of methods resulting
    in systems such as DES (Data Encryption Standard).  The basics of public
    key encryption is introduced in chapter ten.  The relative security of
    encryption is introduced in chapter eleven, leading to part two.  However,
    it also ends with a discussion of cryptology and human rights,
    concentrating mainly, although not exclusively, on the US public policy
    Part two examines the limits of functions used in cryptography, and thus
    the points of attack on encryption systems.  Chapter twelve calculates
    complexity, and thus the size of brute force attacks.  Known plaintext
    attacks are the basis of chapters thirteen to fifteen, looking first at
    general patterns, then at probable words, and finally at frequencies. 
    Frequency leads to a discussion of invariance in chapter sixteen.  Chapter
    seventeen follows with a look at key periodicity.  Alignment of alphabets
    is covered in chapter eighteen.  Of course, cryptographic users sometimes
    make mistakes, and chapter nineteen reviews the different errors and
    various ways to take advantage of them.  Chapter twenty one looks at
    anagrams as an effective attack on transposition ciphers.  The concluding
    chapter muses on the relative effectiveness of attacks and of
    cryptanalysis overall. 
    Those seriously interested in cryptology will really need to be serious:
    brush up on your number theory if you want to use this book for anything. 
    On the other hand, Bauer's history and vignettes from the story of codes
    and the codebreakers are interesting, amusing, and accessible to anyone. 
    copyright Robert M. Slade, 1998   BKDECSEC.RVW   980804
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