[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

DES, the Data Encryption Standard, is one of several cryptographic standards. The authors of this text detail their cryptanalytic "attack" upon DES and several other systems, using creative and novel tactics to demonstrate how they broke DES up into 16 rounds of coding. The methodology used offers valuable insights to cryptographers and cryptanalysts alike in creating new encryption standards, strengthening current ones, and exploring new ways to test important data protection schemes. This book introduces a new cryptographic method, called differential cryptanalysis, which can be applied to analyze cryptosystems. It describes the cryptanalysis of DES, deals with the influence of its building blocks on security, and analyzes modified variants. The differential cryptanalysis of "Feal" and several other cryptosystems is also described. This method can also be used to cryptanalyze hash functions, as is exemplified by the cryptanalysis of "Snefru".

Differential Cryptanalysis of the Data Encryption Standard

Introduction A fundamental objective of cryptography is to enable two persons to communicate over an insecure channel (a public channel such as the internet) in such a way that any other person is unable to recover their message (called the plaintext ) from what is sent in its place over the channel (the ciphertext ). The transformation of the plaintext into the ciphertext is called encryption , or enciphering. Encryption-decryption is the most ancient cryptographic activity (ciphers already existed four centuries b.c.), but its nature has deeply changed with the invention of computers, because the cryptanalysis (the activity of the third person, the eavesdropper, who aims at recovering the message) can use their power. The encryption algorithm takes as input the plaintext and an encryption key K E , and it outputs the ciphertext. If the encryption key is secret, then we speak of conventional cryptography , of private key cryptography , or of symmetric cryptography . In practice, the principle of conventional cryptography relies on the sharing of a private key between the sender of a message (often called Alice in cryptography) and its receiver (often called Bob). If, on the contrary, the encryption key is public, then we speak of public key cryptography . Public key cryptography appeared in the literature in the late 1970s.

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Boolean Models and Methods in Mathematics, Computer Science, and Engineering: Boolean Functions for Cryptography and Error-Correcting Codes

Blowfish, a new secret-key block cipher, is proposed. It is a Feistel network, iterating a simple encryption function 16 times. The block size is 64 bits, and the key can be any length up to 448 bits. Although there is a complex initialization phase required before any encryption can take place, the actual encryption of data is very efficient on large microprocessors.

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Description of a New Variable-Length Key, 64-bit Block Cipher (Blowfish)

Almost bent functions oppose an optimum resistance to linear and differential cryptanalysis. We present basic properties of almost bent functions; particularly we give an upper bound on the degree. We develop the "coding theory" point of view for studying the existence of almost bent functions, showing explicitly the links with cyclic codes. We also give new characterizations of almost bent functions by means of associated Boolean functions.

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Codes, Bent Functions and Permutations Suitable For DES-likeCryptosystems

Boolean functions are the building blocks of symmetric cryptographic systems. Symmetrical cryptographic algorithms are fundamental tools in the design of all types of digital security systems (i.e. communications, financial and e-commerce). "Cryptographic Boolean Functions and Applications" is a concise reference that shows how Boolean functions are used in cryptography. Currently, practitioners who need to apply Boolean functions in the design of cryptographic algorithms and protocols need to patch together needed information from a variety of resources (books, journal articles and other sources). This book compiles the key essential information in one easy to use, step-by-step reference. Beginning with the basics of the necessary theory, the book goes on to examine more technical topics, some of which are at the frontier of current research. The book serves as a complete resource for the successful design or implementation of cryptographic algorithms or protocols using Boolean functions; provides engineers and scientists with a needed reference for the use of Boolean functions in cryptography; and, addresses the issues of cryptographic Boolean functions theory and applications in one concentrated resource. The book is organized logically to help the reader easily understand the topic.

Cryptographic Boolean Functions and Applications

In 1972 Niho gave various conjectures about the crosscorrelation between a binary maximum-length linear shift register sequence and a decimation of that sequence by an integer d. We prove that the crosscorrelation function for two new values of d takes on precisely three values and thereby confirm two of Niho's conjectures.

Some new three-valued crosscorrelation functions for binary m-sequences

Fast evaluation, weights and nonlinearity of rotation-symmetric functions

View-obstruction problems in n-dimensional geometry

Under mild conditions on n, p, we give a lower bound on the number of n-variable balanced symmetric polynomials over finite fields GF(p), where p is a prime number. The existence of nonlinear balanced symmetric polynomials is an immediate corollary of this bound. Furthermore, we prove that X(2t, 2t+1lscr-1) are balanced and conjecture that these are the only balanced symmetric polynomials over GF(2), where X(d, n) = Sigma1lesi 1 <i 2 <hellip<i d lesnxi 1xi 2hellipxi d.

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Thomas W. Cusick

Papers

Cryptographic Boolean Functions and Applications

Some new three-valued crosscorrelation functions for binary m-sequences

Fast evaluation, weights and nonlinearity of rotation-symmetric functions

View-obstruction problems in n-dimensional geometry

Balanced Symmetric Functions Over ${\hbox{GF}}(p)$