applied cryptography - protocols, algorithms, and source code in c

The strength of skipjack against a cryptanalytic

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Unformatted text preview: in part in any form or medium without express written permission of EarthWeb is prohibited. Read EarthWeb's privacy statement. To access the contents, click the chapter and section titles. Applied Cryptography, Second Edition: Protocols, Algorthms, and Source Code in C (cloth) Go! Keyword Brief Full Advanced Search Search Tips (Publisher: John Wiley & Sons, Inc.) Author(s): Bruce Schneier ISBN: 0471128457 Publication Date: 01/01/96 Search this book: Go! Previous Table of Contents Next ----------- Security of MMB The design of MMB ensures that each round has considerable diffusion independent of the key. In IDEA, the amount of diffusion is to some extent dependent on the particular subkeys. MMB was also designed not to have any weak keys as IDEA has. MMB is dead [402]. Although no cryptanalysis has been published, this is true for several reasons. First, it was not designed to be resistant to linear cryptanalysis. The multiplication factors were chosen to be resistant to differential cryptanalysis, but the algorithm’s authors were unaware of linear cryptanalysis. Second, Eli Biham has an effective chosen-key attack [160], which exploits the fact that all rounds are identical and that the key schedule is just a cyclic shift by 32 bits. Third, even though MMB would be very efficient in software, the algorithm would be less efficient than DES in hardware. Daemen suggests that anyone interested in improving MMB should first do an analysis of modular multiplication with respect to linear cryptanalysis and choose a new multiplication factor, and then make the constant C different for each round [402]. Then, improve the key scheduling by adding constants to the round keys to remove the bias. He’s not going to do it; he designed 3-Way instead (see Section 14.5). 13.11 CA-1.1 CA is a block cipher built on cellular automata, designed by Howard Gutowitz [677, 678, 679]. It encrypts plaintext in 384-bit blocks and has a 1088-bit key (it’s really two keys, a 1024-bit key and a 64-bit key). Because of the nature of cellular automata, the algorithm is most efficient when implemented in massively p...
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This note was uploaded on 10/18/2010 for the course MATH CS 301 taught by Professor Aliulger during the Fall '10 term at Koç University.

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