-->
Navigation
Decrypted Secrets: Methods & Maxims of Cryptology. Springer

Decrypted Secrets: Methods & Maxims of Cryptology. Springer

Now pay Easier and Secure using Paypal
Price:

Read more

Friedrich L. Bauer

4th, Revised & Extended Edition

With 191 Figures, 29 Tables, and 16 Color Plates


e-books shop
Decrypted Secrets
Methods & Maxims of Cryptology


Dr. rer. nat. Dr. ès sc. h.c. Dr. rer. nat. h.c. mult. Friedrich L. Bauer
Professor Emeritus of Mathematics and Computer Science
Munich Institute of Technology
Department of Computer Science
Boltzmannstr. 3
85748 Garching, Germany

__________________________________________________
ACM Computing Classification (1998): E.3, D.4.6, K.6.5, E.4
Mathematics Subject Classification (1991): 94A60, 68P25
_______________________________________
Library of Congress Control Number: 2006933429

ISBN-10 3-540-24502-2 Springer Berlin Heidelberg New York
ISBN-13 978-3-540-24502-5 Springer Berlin Heidelberg New York
ISBN 3-540-42674-4 3rd ed. Springer Berlin Heidelberg New York

This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable for prosecution under the German Copyright Law.

Springer is a part of Springer Science+Business Media
springer.com

Preface
Towards the end of the 1960s, under the influence of the rapid development
of microelectronics, electromechanical cryptological machines began to be
replaced by electronic data encryption devices using large-scale integrated
circuits. This promised more secure encryption at lower prices. Then, in
1976, Diffie and Hellman opened up the new cryptological field of public-key
systems. Cryptography, hitherto cloaked in obscurity, was emerging into the
public domain. Additionally, ENIGMA revelations awoke the public interest.
Computer science was a flourishing new field, too, and computer scientists
became interested in several aspects of cryptology. But many of them were
not well enough informed about the centuries-long history of cryptology and
the high level it had attained. I saw some people starting to reinvent the
wheel, and others who had an incredibly naive belief in safe encryption,
and I became worried about the commercial and scientific development of
professional cryptology among computer scientists and about the unstable
situation with respect to official security services.

This prompted me to offer lectures on this subject at the Munich Institute of
Technology. The first series of lectures in the winter term 1977/78, backed
by the comprehensive and reliable book The Codebreakers (1967) by David
Kahn, was held under the code name ‘Special Problems of Information
Theory’ and therefore attracted neither too many students nor too many
suspicious people from outside the university.

Next time, in the summer term of 1981, my lectures on the subject were
announced under the open title ‘Cryptology’. This was seemingly the first
publicly announced lecture series under this title at a German, if not indeed
a Continental European, university.

The series of lectures was repeated a few times, and in 1986/87 lecture notes
were printed which finally developed into Part I of this book. Active interest
on the side of the students led to a seminar on cryptanalytic methods in the
summer term of 1988, from which Part II of the present book originated.
The 1993 first edition (in German) of my book Kryptologie, although written
mainly for computer science students, found lively interest also outside the
field. It was reviewed favorably by some leading science journalists, and
the publisher followed the study book edition with a 1995 hardcover edition
under the title Entzifferte Geheimnisse [Decrypted Secrets], which gave me
the opportunity to round out some subjects. Reviews in American journals
recommended also an English version, which led in 1997 to the present book.
It has become customary among cryptologists to explain how they became
acquainted with the field. In my case, this was independent of the Second
World War. In fact, I was never a member of any official service—and I
consider this my greatest advantage, since I am not bound by any pledge of
secrecy. On the other hand, keeping eyes and ears open and reading between
the lines, I learned a lot from conversations (where my scientific metier was
a good starting point), although I never know exactly whether I am allowed
to know what I happen to know.

Luigi Sacco (1883–1970)
It all started in 1951, when I told my former professor
of formal logic at Munich University, Wilhelm Britzelmayr,
of my invention of an error-correcting code
for teletype lines1. This caused him to make a wrong
association, and he gave me a copy of Sacco’s book,
which had just appeared2. I was lucky, for it was the
best book I could have encountered at that time—
although I didn’t know that then. I devoured the
book. Noticing this, my dear friend and colleague
Paul August Mann, who was aware of my acquaintance
with Shannon’s redundancy-decreasing encoding,
gave me a copy of the now-famous paper by
Claude Shannon called Communication Theory of Secrecy Systems3 (which
in those days as a Bell Systems Technical Report was almost unavailable in
Germany). I was fascinated by this background to Shannon’s information
theory, which I was already familiar with. This imprinted my interest in
cryptology as a subfield of coding theory and formal languages theory, fields
that held my academic interest for many years to come.

Strange accidents—or maybe sharper observation—then brought me into
contact with more and more people once close to cryptology, starting with
Willi Jensen (Flensburg) in 1955, Karl Stein (Munich) in 1955, Hans Rohrbach,
my colleague at Mainz University, in 1959, as well as Helmut Grunsky,
Gisbert Hasenj¨ager, and Ernst Witt. In 1957, I became acquainted with
Erich H¨uttenhain (Bad Godesberg), but our discussions on the suitability of
certain computers for cryptological work were in the circumstances limited
by certain restrictions. Among the American and British colleagues in numerical
analysis and computer science I had closer contact with, some had
been involved with cryptology in the Second World War; but no one spoke
about that, particularly not before 1974, the year when Winterbotham’s book
The Ultra Secret appeared. In 1976, I heard B. Randall and I. J. Good reveal
some details about the Colossi in a symposium in Los Alamos. As a scienceoriented
civilian member of the cryptology academia, my interest in cryptology
was then and still is centered on computerized cryptanalysis. Other
aspects of signals intelligence (‘SIGINT’), for example, traffic analysis and direction
finding, are beyond the scope of this book; the same holds for physical
devices that screen electromechanical radiation emitted by cipher machines.

Cryptology is a discipline with an international touch and a particular terminology.
It may therefore be helpful sometimes to give in this book some
explanations of terms that originated in a language other than English.
The first part of this book presents cryptographic methods. The second part
covers cryptanalysis, above all the facts that are important for judging cryptographic
methods and for saving the user from unexpected pitfalls. This
follows from Kerckhoffs’ maxim: Only a cryptanalyst can judge the security
of a cryptosystem. A theoretical course on cryptographic methods alone
seems to me to be bloodless. But a course on cryptanalysis is problematic:
Either it is not conclusive enough, in which case it is useless, or it is conclusive,
but touches a sensitive area. There is little clearance in between. I have
tried to cover at least all the essential facts that are in the open literature or
can be deduced from it. No censorship took place.

Certain difficulties are caused by the fact that governmental restrictions during
and after World War II, such as the ‘need to know’ rule and other gimmicks,
misled even people who had been close to the centers of cryptanalysis.
Examples include the concept of Banburismus and the concept of a ‘cilli’.
The word Banburismus—the name was coined in Britain—was mentioned in
1985 by Deavours and Kruh in their book, but the method was only vaguely
described. Likewise, the description Kahn gave in 1991 in his book is rather
incomplete. On the other hand, in Kozaczuk’s book of 1979 (English edition
of 1984), Rejewski gave a description of R´o˙zycki’s ‘clock method’, which
turned out to be the same—but most of the readers could not know of this
connection. Then, in 1993, while giving a few more details on the method,
Good (in ‘Codebreakers’) confirmed that “Banburism was an elaboration
of ... the clock method ... [of] ... R´o˙zycki”. He also wrote that this elaboration
was ‘invented at least mainly by Turing’, and referred to a sequential
Bayesian process as the “method of scoring”. For lack of declassified concrete
examples, the exposition in Sect. 19.4.2 of the present book, based on the recently
published postwar notes of Alexander and of Mahon and articles by
Erskine and by Noskwith in the recent book Action This Day, cannot yet be
a fully satisfactory one. And as to cillies, even Gordon Welchman admitted
that he had misinterpreted the origin of the word, thinking of ‘silly’. Other
publications gave other speculations, see Sect. 19.7, fn. 29. Ralph Erskine, in
Action This Day, based on the recently declassified ‘Cryptanalytic Report
on the Yellow Machine’, 71-4 (NACP HCC Box 1009, Nr. 3175), gives the
following summary of the method:
‘Discovered by Dilly Knox in late January 1940, cillies reduced enormously
the work involved in using the Zygalski sheets, and after 1 May, when the
Zygalski sheets became useless, they became a vital part of breaking Enigma
by hand during most of 1940. They were still valuable in 1943.
Cillies resulted from a combination of two different mistakes in a multi-part
message by some Enigma operators. The first was their practice of leaving
the rotors untouched when they reached the end of some part of the message.
Since the letter count of each message part was included in the preamble, the
message key of the preceding part could be calculated within fine limits. The
second error was the use of non-random message keys—stereotyped keyboard
touches and 3-letter-acronyms. In combination, and in conjunction with the
different turnover points of rotors I to V, they allowed one to determine which
rotors could, and which could not, be in any given position in the machine.’
Although Banburismus and cillies were highly important in the war, it is
hard to understand why Derek Taunt in 1993 was prevented by the British
censor from telling the true story about cillies. Possibly, the same happened
to Jack Good about Banburismus.
***
My intellectual delight in cryptology found an application in the collection
‘Informatik’ of the Deutsches Museum in Munich which I built up in 1984
–1988, where there is a section on cryptological devices and machines. My
thanks go to the Deutsches Museum for providing color plates of some of the
pieces on exhibit there.

And thanks go to my former students and co-workers in Munich, Manfred
Broy, Herbert Ehler, and Anton Gerold for continuing support over the years,
moreover to Hugh Casement for linguistic titbits, and to my late brotherin-
law Alston S. Householder for enlightenment on my English. Karl Stein
and Otto Leiberich gave me details on the ENIGMA story, and I had fruitful
discussions and exchanges of letters with Ralph Erskine, Heinz Ulbricht, Tony
Sale, Frode Weierud, Kjell-Ove Widman, Otto J. Horak, Gilbert Bloch, Arne
Frans´en, and Fritz-Rudolf G¨untsch. Great help was given to me by Kirk
H. Kirchhofer from Crypto AG, Zug (Switzerland). Hildegard Bauer-Vogg
supplied translations of difficult Latin texts, Martin Bauer, Ulrich Bauer and
Bernhard Bauer made calculations and drawings. Thanks go to all of them.

The English version was greatly improved by J. Andrew Ross, with whom
working was a pleasure. In particular, my sincere thanks go to David Kahn
who encouraged me (“The book is an excellent one and deserves the widest
circulation”) and made quite a number of proposals for improvements of the
text. For the present edition, additional material that has been made public
recently has been included, among others on Bletchley Park, the British attack
on Tunny, Colossus and Max Newman’s pioneering work. Moreover, my
particular thanks go to Ralph Erskine who indefatigably provided me with
a lot of additional information and checked some of the dates and wordings.
In this respect, my thanks also go to Jack Copeland, Heinz Ulbricht, and
Augusto Buonafalce. Finally, I have to thank once more Hans W¨ossner for
a well functioning cooperation of long standing, and the new copy editor
Ronan Nugent for very careful work. The publisher is to be thanked for the
fine presentation of the book. And I shall be grateful to readers who are kind
enough to let me know of errors and omissions.
Grafrath, Spring 2006 
F. L. Bauer


Table of Contents
Part I: Cryptography—The People . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 Introductory Synopsis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
1.1 Cryptography and Steganography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2 Semagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3 Open Code: Masking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.4 Cues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.5 Open Code: Veiling by Nulls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.6 Open Code: Veiling by Grilles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.7 Classification of Cryptographic Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2 Aims and Methods of Cryptography . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.1 The Nature of Cryptography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.2 Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.3 Cryptosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.4 Polyphony . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.5 Character Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.6 Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3 Encryption Steps: Simple Substitution . . . . . . . . . . . . . . . . . . . . . . 44
3.1 Case V (1) −−− W (Unipartite Simple Substitutions) . . . . . . . . . . . . . 44
3.2 Special Case V ≺−−−− V (Permutations) . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.3 Case V (1) −−− Wm (Multipartite Simple Substitutions) . . . . . . . . . . . 53
3.4 The General Case V (1) −−− W(m) , Straddling . . . . . . . . . . . . . . . . . . . 55
4 Encryption Steps: Polygraphic Substitution and Coding . 58
4.1 Case V 2 −−− W(m) (Digraphic Substitutions) . . . . . . . . . . . . . . . . . . 58
4.2 Special Cases of Playfair and Delastelle: Tomographic Methods . . . . 64
4.3 Case V 3 −−− W(m) (Trigraphic Substitutions) . . . . . . . . . . . . . . . . . . 68
4.4 The General Case V (n) −−− W(m) : Codes . . . . . . . . . . . . . . . . . . . . . . 68
5 Encryption Steps: Linear Substitution . . . . . . . . . . . . . . . . . . . . . . . . 80
5.1 Self-reciprocal Linear Substitutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.2 Homogeneous Linear Substitutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.3 Binary Linear Substitutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
5.4 General Linear Substitutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
5.5 Decomposed Linear Substitutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.6 Decimated Alphabets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
5.7 Linear Substitutions with Decimal and Binary Numbers . . . . . . . . . 91
6 Encryption Steps: Transposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.1 Simplest Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.2 Columnar Transpositions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.3 Anagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
7 Polyalphabetic Encryption: Families of Alphabets. . . . . . . . .106
7.1 Iterated Substitutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106
7.2 Cyclically Shifted and Rotated Alphabets . . . . . . . . . . . . . . . . . . . . . . . . 107
7.3 Rotor Crypto Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7.4 Shifted Standard Alphabets: Vigen`ere and Beaufort . . . . . . . . . . . . . 127
7.5 Unrelated Alphabets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131
8 Polyalphabetic Encryption: Keys . . . . . . . . . . . . . . . . . . . . . . . . . . .139
8.1 Early Methods with Periodic Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
8.2 ‘Double Key’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
8.3 Vernam Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
8.4 Quasi-nonperiodic Keys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144
8.5 Machines that Generate Their Own Key Sequences . . . . . . . . . . . . . . . 145
8.6 Off-Line Forming of Key Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
8.7 Nonperiodic Keys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158
8.8 Individual, One-Time Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
8.9 Key Negotiation and Key Management. . . . . . . . . . . . . . . . . . . . . . . . . . .165
9 Composition of Classes of Methods . . . . . . . . . . . . . . . . . . . . . . . . 169
9.1 Group Property . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
9.2 Superencryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
9.3 Similarity of Encryption Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
9.4 Shannon’s ‘Pastry Dough Mixing’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
9.5 Confusion and Diffusion by Arithmetical Operations. . . . . . . . . . . . . .180
9.6 DES and IDEAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
10 Open Encryption Key Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
10.1 Symmetric and Asymmetric Encryption Methods. . . . . . . . . . . . . . . . .194
10.2 One-Way Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
10.3 RSA Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
10.4 Cryptanalytic Attack upon RSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
10.5 Secrecy Versus Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
10.6 Security of Public Key Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
11 Encryption Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
11.1 Cryptographic Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
11.2 Maxims of Cryptology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
11.3 Shannon’s Yardsticks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
11.4 Cryptology and Human Rights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Part II: Cryptanalysis—The Machinery . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
12 Exhausting Combinatorial Complexity . . . . . . . . . . . . . . . . . . . . . 237
12.1 Monoalphabetic Simple Encryptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
12.2 Monoalphabetic Polygraphic Encryptions . . . . . . . . . . . . . . . . . . . . . . . . 239
12.3 Polyalphabetic Encryptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
12.4 General Remarks on Combinatorial Complexity . . . . . . . . . . . . . . . . . . 244
12.5 Cryptanalysis by Exhaustion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .244
12.6 Unicity Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
12.7 Practical Execution of Exhaustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
12.8 Mechanizing the Exhaustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
13 Anatomy of Language: Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
13.1 Invariance of Repetition Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
13.2 Exclusion of Encryption Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
13.3 Pattern Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
13.4 Finding of Polygraphic Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
13.5 The Method of the Probable Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
13.6 Automatic Exhaustion of the Instantiations of a Pattern . . . . . . . . . 264
13.7 Pangrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
14 Polyalphabetic Case: Probable Words . . . . . . . . . . . . . . . . . . . . . 268
14.1 Non-Coincidence Exhaustion of Probable Word Position . . . . . . . . . 268
14.2 Binary Non-Coincidence Exhaustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . .271
14.3 The De Viaris Attack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
14.4 Zig-Zag Exhaustion of Probable Word Position . . . . . . . . . . . . . . . . . . . 280
14.5 The Method of Isomorphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
14.6 A clever brute force method: EINSing. . . . . . . . . . . . . . . . . . . . . . . . . . . .287
14.7 Covert Plaintext-Cryptotext Compromise . . . . . . . . . . . . . . . . . . . . . . . . 288
15 Anatomy of Language: Frequencies . . . . . . . . . . . . . . . . . . . . . . . . 290
15.1 Exclusion of Encryption Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
15.2 Invariance of Partitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
15.3 Intuitive Method: Frequency Profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .293
15.4 Frequency Ordering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .294
15.5 Cliques and Matching of Partitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297
15.6 Optimal Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
15.7 Frequency of Multigrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
15.8 The Combined Method of Frequency Matching . . . . . . . . . . . . . . . . . . . 310
15.9 Frequency Matching for Polygraphic Substitutions . . . . . . . . . . . . . . . 316
15.10 Free-Style Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
15.11 Unicity Distance Revisited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318
16 Kappa and Chi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
16.1 Definition and Invariance of Kappa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
16.2 Definition and Invariance of Chi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
16.3 The Kappa-Chi Theorem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
16.4 The Kappa-Phi Theorem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
16.5 Symmetric Functions of Character Frequencies . . . . . . . . . . . . . . . . . . 328
17 Periodicity Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
17.1 The Kappa Test of Friedman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
17.2 Kappa Test for Multigrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
17.3 Cryptanalysis by Machines: Searching for a period . . . . . . . . . . . . . . 333
17.4 Kasiski Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
17.5 Building a Depth and Phi Test of Kullback . . . . . . . . . . . . . . . . . . . . . . 345
17.6 Estimating the Period Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348
18 Alignment of Accompanying Alphabets . . . . . . . . . . . . . . . . . . . 350
18.1 Matching the Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
18.2 Aligning Against Known Alphabet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
18.3 Chi Test: Mutual Alignment of Accompanying Alphabets. . . . . . . . 358
18.4 Reconstruction of the Primary Alphabet . . . . . . . . . . . . . . . . . . . . . . . . 363
18.5 Kerckhoffs’ Symmetry of Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
18.6 Stripping off Superencryption: Difference Method . . . . . . . . . . . . . . . 370
18.7 Decryption of Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373
18.8 Reconstruction of the Password . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373
19 Compromises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
19.1 Kerckhoffs’ Superimposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
19.2 Superimposition for Encryptions with a Key Group. . . . . . . . . . . . . . 377
19.3 COLOSSUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
19.4 Adjustment ‘in depth’ of Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412
19.5 Cryptotext-Cryptotext Compromises . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
19.6 Cryptotext-Cryptotext Compromise: ENIGMAIndicator Doubling 431
19.7 Plaintext-Cryptotext Compromise: Feedback Cycle . . . . . . . . . . . . . . 448
20 Linear Basis Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 459
20.1 Reduction of Linear Polygraphic Substitutions. . . . . . . . . . . . . . . . . . . 459
20.2 Reconstruction of the Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 460
20.3 Reconstruction of a Linear Shift Register . . . . . . . . . . . . . . . . . . . . . . . . 461
21 Anagramming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464
21.1 Transposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464
21.2 Double Columnar Transposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467
21.3 Multiple Anagramming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467
22 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 470
22.1 Success in Breaking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
22.2 Mode of Operation of the Unauthorized Decryptor . . . . . . . . . . . . . . 476
22.3 Illusory Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482
22.4 Importance of Cryptology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 484
Appendix: Axiomatic Information Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . 487
Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501
Photo Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525

List of Color Plates
Plate A The disk of Phaistos
Plate B Brass cipher disks
Plate C The ‘Cryptograph’ of Wheatstone
Plate D The US Army cylinder device M-94
Plate E The US strip device M-138-T4
Plate F The cipher machine of Kryha
Plate G The Hagelin ‘Cryptographer’ C-36
Plate H The US Army M-209, Hagelin licensed
Plate I The cipher machine ENIGMA with four rotors
Plate K Rotors of the ENIGMA
Plate L The British rotor machine TYPEX
Plate M Uhr box of the German Wehrmacht
Plate N Cipher teletype machine Lorenz SZ 42
Plate O Russian one-time pad
Plate P Modern crypto board
Plate Q CRAY Supercomputers


Screenshot

e-books shop

Purchase Now !
Just with Paypal



Product details
 Price
 Pages
 555 p
 File Size
 17,598 KB
 File Type
 PDF format
 ISBN-10
 ISBN-13
 3-540-24502-2
 978-3-540-24502-5
 Copyright
 Springer-Verlag Berlin Heidelberg 
 1997, 2000, 2002, 2007
  ●▬▬▬▬▬❂❂❂▬▬▬▬▬●
●▬▬❂❂▬▬●
●▬❂▬●

═════ ═════