Cover image for Decrypted secrets : methods and maxims of cryptology
Title:
Decrypted secrets : methods and maxims of cryptology
Author:
Bauer, Friedrich Ludwig, 1924-
Edition:
Second revised and extended edition.
Publication Information:
Berlin ; New York : Springer, [2000]

©2000
Physical Description:
xii, 470 pages : illustrations (some color) ; 25 cm
Language:
English
ISBN:
9783540668718
Format :
Book

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Summary

Summary

Cryptology, for millennia a "secret science," is rapidly gaining in practical importance for the protection of communication channels, databases, & software. Beside its role in computerized information systems (public key systems), more & more applications within computer systems & networks are appearing, which also extend to access rights & source file protection. The first part of this book treats secret codes & their uses - cryptography. The second part deals with the process of covertly decrypting a secret code - cryptanalysis - where in particular advice on assessing methods is given. The book presupposes only elementary mathematical knowledge. Spiced with a wealth of exciting, amusing, & sometimes personal stories from the history of cryptology, it will also interest general readers. Decrypted Secrets has become a standard book on cryptology. The new edition has been revised & extended in many details.


Table of Contents

Part I Cryptographyp. 1
1 Introductory Synopsisp. 8
1.1 Cryptography and Steganographyp. 8
1.2 Semagramsp. 9
1.3 Open Code: Maskingp. 12
1.4 Cuesp. 16
1.5 Open Code: Veiling by Nullsp. 18
1.6 Open Code: Veiling by Grillesp. 22
1.7 Classification of Cryptographic Methodsp. 24
2 Aims and Methods of Cryptographyp. 25
2.1 The Nature of Cryptographyp. 25
2.2 Encryptionp. 31
2.3 Cryptosystemsp. 33
2.4 Polyphonyp. 35
2.5 Character Setsp. 37
2.6 Keysp. 40
3 Encryption Steps: Simple Substitutionp. 42
3.1 Case V^{{(1)}} \longrightarrow W (Unipartite Simple Substitutions)p. 42
3.2 Special Case V \longleftrightarrow V (Permutations)p. 44
3.3 Case V^{{(1)}} \longrightarrow W^m (Multipartite Simple Substitutions)p. 51
3.4 The General Case V^{{(1)}} \longrightarrow W^{{(m)}} , Straddlingp. 53
4 Encryption Steps: Polygraphic Substitution and Codingp. 56
4.1 Case V^2 \longrightarrow W^{{(m)}} (Digraphic Substitutions)p. 56
4.2 Special Cases of Playfair and Delastelle: Tomographic Methodsp. 62
4.3 Case V^3 \longrightarrow W^{{(m)}} (Trigraphic Substitutions)p. 66
4.4 The General Case V^{{(n)}} \longrightarrow W^{{(m)}} : Codesp. 66
5 Encryption Steps: Linear Substitutionp. 78
5.1 Self-reciprocal Linear Substitutionsp. 80
5.2 Homogeneous Linear Substitutionsp. 80
5.3 Binary Linear Substitutionsp. 84
5.4 GeneralLinear Substitutionsp. 84
5.5 Decomposed Linear Substitutionsp. 85
5.6 Decimated Alphabetsp. 88
5.7 Linear Substitutions with Decimaland Binary Numbersp. 89
6 Encryption Steps: Transpositionp. 91
6.1 Simplest Methodsp. 91
6.2 Columnar Transpositionsp. 95
6.3 Anagramsp. 98
7 Polyalphabetic Encryption: Families of Alphabetsp. 101
7.1 Iterated Substitutionsp. 101
7.2 Shifted and Rotated Alphabetsp. 102
7.3 Rotor Crypto Machinesp. 105
7.4 Shifted Standard Alphabets: Vigenère and Beaufortp. 114
7.5 Unrelated Alphabetsp. 118
8 Polyalphabetic Encryption: Keysp. 126
8.1 Early Methods with Periodic Keysp. 126
8.2 `Double Key'p. 128
8.3 Vernam Encryptionp. 129
8.4 Quasi-nonperiodic Keysp. 131
8.5 Machines that Generate Their Own Key Sequencesp. 132
8.6 Off-Line Forming of Key Sequencesp. 143
8.7 Nonperiodic Keysp. 144
8.8 Individual, One Time Keysp. 148
8.9 Key Negotiation and Key Managementp. 151
9 Composition of Classes of Methodsp. 155
9.1 Group Propertyp. 155
9.2 Superencryptionp. 157
9.3 Similarity of Encryption Methodsp. 159
9.4 Shannon's `Pastry Dough Mixing'p. 160
9.5 Confusion and Diffusion by ArithmeticalOperationsp. 166
9.6 DES and IDEAp. 170
10 Open Encryption Key Systemsp. 179
10.1 Symmetric and Asymmetric Encryption Methodsp. 180
10.2 One-Way Functionsp. 182
10.3 RSA Methodp. 189
10.4 Cryptanalytic Attack upon RSAp. 191
10.5 Secrecy Versus Authenticationp. 194
10.6 Security of Public Key Systemsp. 196
11 Encryption Securityp. 197
11.1 Cryptographic Faultsp. 197
11.2 Maxims of Cryptologyp. 205
11.3 Shannon's Yardsticksp. 210
11.4 Cryptology and Human Rightsp. 211
Part II Cryptanalysisp. 217
12 Exhausting Combinatorial Complexityp. 220
12.1 Monoalphabetic Simple Encryptionsp. 221
12.2 Monoalphabetic Polygraphic Encryptionsp. 222
12.3 Polyalphabetic Encryptionsp. 225
12.4 GeneralRemarks on Combinatorial Complexityp. 227
12.5 Cryptanalysis by Exhaustionp. 227
12.6 Unicity Distancep. 229
12.7 Practical Execution of Exhaustionp. 231
12.8 Mechanizing the Exhaustionp. 234
13 Anatomy of Language: Patternsp. 235
13.1 Invariance of Repetition Patternsp. 235
13.2 Exclusion of Encryption Methodsp. 237
13.3 Pattern Findingp. 238
13.4 Finding of Polygraphic Patternsp. 242
13.5 The Method of the Probable Wordp. 242
13.6 Automatic Exhaustion of the Instantiations of a Patternp. 247
13.7 Pangramsp. 249
14 Polyalphabetic Case: Probable Wordsp. 251
14.1 Non-Coincidence Exhaustion of Probable Word Positionp. 251
14.2 Binary Non-Coincidence Exhaustion of Probable Word Positionp. 254
14.3 The De Viaris Attackp. 255
14.4 Zig-Zag Exhaustion of Probable Word Positionp. 263
14.5 The Method of Isomorphsp. 264
14.6 Covert Plaintext-Cryptotext Compromisep. 270
15 Anatomy of Language: Frequenciesp. 271
15.1 Exclusion of Encryption Methodsp. 271
15.2 Invariance of Partitionsp. 272
15.3 Intuitive Method: Frequency Profilep. 274
15.4 Frequency Orderingp. 275
15.5 Cliques and Matching of Partitionsp. 278
15.6 Optimal Matchingp. 284
15.7 Frequency of Multigramsp. 286
15.8 The Combined Method of Frequency Matchingp. 291
15.9 Frequency Matching for Polygraphic Substitutionsp. 297
15.10 Free-Style Methodsp. 298
15.11 Unicity Distance Revisitedp. 299
16 Kappa and Chip. 301
16.1 Definition and Invariance of Kappap. 301
16.2 Definition and Invariance of Chip. 304
16.3 The Kappa-Chi Theoremp. 306
16.4 The Kappa-Phi Theoremp. 307
16.5 Symmetric Functions of Character Frequenciesp. 309
17 Periodicity Examinationp. 311
17.1 The Kappa Test of Friedmanp. 312
17.2 Kappa Test for Multigramsp. 313
17.3 Cryptanalysis by Machinesp. 314
17.4 Kasiski Examinationp. 320
17.5 Building a Depth and Phi Test of Kullbackp. 326
17.6 Estimating the Period Lengthp. 329
18 Alignment of Accompanying Alphabetsp. 331
18.1 Matching the Profilep. 331
18.2 Aligning Against Known Alphabetp. 335
18.3 Chi Test: Mutual Alignment of Accompanying Alphabetsp. 339
18.4 Reconstruction of the Primary Alphabetp. 344
18.5 Kerckhoffs' Symmetry of Positionp. 346
18.6 Stripping off Superencryption: Difference Methodp. 351
18.7 Decryption of Codep. 354
18.8 Reconstruction of the Passwordp. 354
19 Compromisesp. 356
19.1 Kerckhoffs' Superimpositionp. 356
19.2 Superimposition for Encryptions with a Key Groupp. 358
19.3 In-Phase Superimposition of Superencrypted Codep. 373
19.4 Cryptotext-Cryptotext Compromisesp. 376
19.5 A Method of Sinkovp. 381
19.6 Cryptotext-Cryptotext Compromise: Doublingp. 388
19.7 Plaintext-Cryptotext Compromise: Feedback Cyclep. 402
20 Linear Basis Analysisp. 412
20.1 Reduction of Linear Polygraphic Substitutionsp. 412
20.2 Reconstruction of the Keyp. 413
20.3 Reconstruction of a Linear Shift Registerp. 414
21 Anagrammingp. 417
21.1 Transpositionp. 417
21.2 Double Columnar Transpositionp. 420
21.3 Multiple Anagrammingp. 420
22 Concluding Remarksp. 423
22.1 Success in Breakingp. 424
22.2 Mode of Operation of the Unauthorized Decryptorp. 429
22.3 Illusory Securityp. 434
22.4 Importance of Cryptologyp. 435
Appendix: Axiomatic Information Theoryp. 438
Bibliographyp. 448
Indexp. 451
Photo Creditsp. 471