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

# 3 for r 0 to 3 for g 0 to 63 a x4g2r b x4g12r

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Unformatted text preview: ecessary, though. I know of no successful cryptanalysis against Blowfish. To be safe, do not implement Blowfish with a reduced number of rounds. Kent Marsh Ltd. has incorporated Blowfish in their FolderBolt security product for Microsoft Windows and Macintosh. It is also part of Nautilus and PGPfone. 14.4 SAFER SAFER K-64 stands for Secure And Fast Encryption Routine with a Key of 64 bits [1009]. James Massey produced this nonproprietary algorithm for Cylink Corp. and it is incorporated into some of their products. The government of Singapore is planning to use this algorithm—with a 128-bit key [1010]—for a wide variety of applications. There are no patent, copyright, or other restrictions on its use. The algorithm has a block and key size of 64 bits. It is not a Feistel network like DES (see Section 14.10), but an iterated block cipher: The same function is applied for some number of rounds. Each round uses two 64-bit subkeys, and the algorithm only uses operations on bytes. Description of SAFER K-64 The plaintext block is divided into eight byte-length sub-blocks: B1, B2,..., B7, B8. Then the sub-blocks go through r rounds. Finally, an output transformation is applied to the sub-blocks. Each round uses two subkeys: K2i - 1 and K2i. Figure 14.4 shows one round of SAFER K-64. First, sub-blocks are either XORed or added with bytes of subkey K2i - 1. Then, the eight sub-blocks are subjected to one of two nonlinear transformations: y = 45x mod 257. (If x = 128, then y = 0.) y = log45 x. (If x = 0, then y = 128.) 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 F...
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