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

Susan langford and hellman have an attack on 8 round

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Unformatted text preview: ts after each round, except for 1 bit after rounds 1, 2, 9, and 16. Why? Related-key cryptanalysis is similar to differential cryptanalysis, but it examines the difference between keys. The attack is different from any previously discussed: The cryptanalyst chooses a relationship between a pair of keys, but does not know the keys themselves. Data is encrypted with both keys. In the known-plaintext version, the cryptanalyst knows the plaintext and ciphertext of data encrypted with the two keys. In the chosen-plaintext version, the cryptanalyst gets to choose the plaintext encrypted with the two keys. A modified DES, where the key is rotated two bits after every round, is less secure. Related-key cryptanalysis can break that variant using 217 chosen-key chosen plaintexts or 233 chosen-key known plaintexts [158,163]. This attack is not at all practical, but it is interesting for three reasons. One, it is the first cryptanalytic attack against DES’s subkey-generation algorithm. Two, this attack is independent of the number of rounds of the cryptographic algorithm; it’s just as effective against DES with 16 rounds, 32 rounds, or 1000 rounds. And three, DES is impervious to this attack. The variability in the rotation thwarts related-key cryptanalysis. Previous Table of Contents Next Products | Contact Us | About Us | Privacy | Ad Info | Home Use of this site is subject to certain Terms & Conditions, Copyright © 1996-2000 EarthWeb Inc. All rights reserved. Reproduction whole or 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 ---------...
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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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