Introduction to Cryptography

Cryptography is a key technology in electronic key systems. It is used to keep data secret, digitally sign documents, access control, etc. Therefore, users should not only know how its techniques work, but they must also be able to estimate their efficiency and security. For this new edition, the author has updated the discussion of the security of encryption and signature schemes and recent advances in factoring and computing discrete logarithms. He has also added descriptions of time-memory trade of attacks and algebraic attacks on block ciphers, the Advanced Encryption Standard, the Secure Hash Algorithm, secret sharing schemes, and undeniable and blind signatures.

Johannes A. Buchmann is a Professor of Computer Science and Mathematics at the Technical University of Darmstadt, and the Associate Editor of the Journal of Cryptology. In 1985, he received the Feodor Lynen Fellowship of the Alexander von Humboldt Foundation. Furthermore, he has received the most prestigious award in science in Germany, the Leibniz Award of the German Science Foundation.

About the first edition:

It is amazing how much Buchmann is able to do in under 300 pages: self-contained explanations of the relevant mathematics (with proofs); a systematic introduction to symmetric cryptosystems, including a detailed description and discussion of DES; a good treatment of primality testing, integer factorization, and algorithms for discrete logarithms; clearly written sections describing most of the major types of cryptosystems....This book is an excellent reference, and I believe it would also be a good textbook for a course for mathematics or computer science majors..."

-Neal Koblitz, The American Mathematical Monthly

1 Integers.- 1.1 Basics.- 1.2 Divisibility.- 1.3 Representation of Integers.- 1.4 O- and ?-Notation.- 1.5 Cost of Addition, Multiplication, and Division with Remainder.- 1.6 Polynomial Time.- 1.7 Greatest Common Divisor.- 1.8 Euclidean Algorithm.- 1.9 Extended Euclidean Algorithm.- 1.10 Analysis of the Extended Euclidean Algorithm.- 1.11 Factoring into Primes.- 1.12 Exercises.- 2 Congruences and Residue Class Rings.- 2.1 Congruences.- 2.2 Semigroups.- 2.3 Groups.- 2.4 Residue Class Rings.- 2.5 Fields.- 2.6 Division in the Residue Class Ring.- 2.7 Analysis of Operations in the Residue Class Ring.- 2.8 Multiplicative Group of Residues.- 2.9 Order of Group Elements.- 2.10 Subgroups.- 2.11 Fermat’s Little Theorem.- 2.12 Fast Exponentiation.- 2.13 Fast Evaluation of Power Products.- 2.14 Computation of Element Orders.- 2.15 The Chinese Remainder Theorem.- 2.16 Decomposition of the Residue Class Ring.- 2.17 A Formula for the Euler ?-Function.- 2.18 Polynomials.- 2.19 Polynomials over Fields.- 2.20 Structure of the Unit Group of Finite Fields.- 2.21 Structure of the Multiplicative Group of Residues mod a Prime Number.- 2.22 Exercises.- 3 Encryption.- 3.1 Encryption Schemes.- 3.2 Symmetric and Asymmetric Cryptosystems.- 3.3 Cryptanalysis.- 3.4 Alphabets and Words.- 3.5 Permutations.- 3.6 Block Ciphers.- 3.7 Multiple Encryption.- 3.8 Use of Block Ciphers.- 3.9 Stream Ciphers.- 3.10 Affine Cipher.- 3.11 Matrices and Linear Maps.- 3.12 Affine Linear Block Ciphers.- 3.13 Vigenère, Hill, and Permutation Ciphers.- 3.14 Cryptanalysis of Affine Linear Block Ciphers.- 3.15 Exercises.- 4 Probability and Perfect Secrecy.- 4.1 Probability.- 4.2 Conditional Probability.- 4.3 Birthday Paradox.- 4.4 Perfect Secrecy.- 4.5 Vernam One-Time Pad.- 4.6 Random Numbers.- 4.7 PseudorandomNumbers.- 4.8 Exercises.- 5 DES.- 5.1 Feistel Ciphers.- 5.2 DES Algorithm.- 5.3 An Example.- 5.4 Security of DES.- 5.5 Exercises.- 6 Prime Number Generation.- 6.1 Trial Division.- 6.2 Fermat Test.- 6.3 Carmichael Numbers.- 6.4 Miller-Rabin Test.- 6.5 Random Primes.- 6.6 Exercises.- 7 Public-Key Encryption.- 7.1 Idea.- 7.2 RSA Cryptosystem.- 7.3 Rabin Encryption.- 7.4 Diffie-Hellman Key Exchange.- 7.5 ElGamal Encryption.- 7.6 Exercises.- 8 Factoring.- 8.1 Trial Division.- 8.2 p — 1 Method.- 8.3 Quadratic Sieve.- 8.4 Analysis of the Quadratic Sieve.- 8.5 Efficiency of Other Factoring Algorithms.- 8.6 Exercises.- 9 Discrete Logarithms.- 9.1 DL Problem.- 9.2 Enumeration.- 9.3 Shanks Baby-Step Giant-Step Algorithm.- 9.4 Pollard ?-Algorithm.- 9.5 Pohlig-Hellman Algorithm.- 9.6 Index Calculus.- 9.7 Other Algorithms.- 9.8 Generalization of the Index Calculus Algorithm.- 9.9 Exercises.- 10 Cryptographic Hash Functions.- 10.1 Hash Functions and Compression Functions.- 10.2 Birthday Attack.- 10.3 Compression Functions from Encryption Functions.- 10.4 Hash Functions from Compression Functions.- 10.5 Efficient Hash Functions.- 10.6 An Arithmetic Compression Function.- 10.7 Message Authentication Codes.- 10.8 Exercises.- 11 Digital Signatures.- 11.1 Idea.- 11.2 RSA Signatures.- 11.3 Signatures from Public-Key Systems.- 11.4 ElGamal Signature.- 11.5 Digital Signature Algorithm (DSA).- 11.6 Exercises.- 12 Other Groups.- 12.1 Finite Fields.- 12.2 Elliptic Curves.- 12.3 Quadratic Forms.- 12.4 Exercises.- 13 Identification.- 13.1 Passwords.- 13.2 One-Time Passwords.- 13.3 Challenge-Response Identification.- 13.4 Exercises.- 14 Public-Key Infrastructures.- 14.1 Personal Security Environments.- 14.2 Certification Authorities.- 14.3 Certificate Chains.- References.- Solutions to theExercises.