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

Another scheme 432 458 was shown insecure in 1606 hi

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Unformatted text preview: urce 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 ----------- 18.8 RIPE-MD RIPE-MD was developed for the European Community’s RIPE project [1305] (see Section 25.7). The algorithm is a variation of MD4, designed to resist known cryptanalytic attacks, and produce a 128-bit hash value. The rotations and the order of the message words are modified. Additionally, two instances of the algorithm, differing only in the constants, run in parallel. After each block, the output of both instances are added to the chaining variables. This seems to make the algorithm highly resistant to cryptanalysis. 18.9 HAVAL HAVAL is a variable-length one-way hash function [1646]. It is a modification of MD5. HAVAL processes messages in blocks of 1024 bits, twice those of MD5. It has eight 32-bit chaining variables, twice those of MD5. It has a variable number of rounds, from three to five (each of which has 16 steps), and it can produce a hash length of 128, 160, 192, 224, or 256 bits. HAVAL replaces MD5’s simple nonlinear functions with highly nonlinear 7-variable functions, each of which satisfies the strict avalanche criterion. Each round uses a single function, but in every step a different permutation is applied to the inputs. It has a new message order and every step (except those in the first round) uses a different additive constant. The algorithm also has two rotations. The core of the algorithm is TEMP = (f(j,A,B,C,D,E,F,G) <<< 7) + (H <<< 11) + M[i][r (j)] + K(j) H = G; G = F; F = E; E = D; D = C; C = B; B = A; A = TEMP The variable number of rounds and variable-length output mean there are 15 versions of this algorithm. Den Boer’s and Bosselaers’s attack against MD5 [203] does not apply to HAVAL because of the rotation of H. 18.10 Other One-Way Hash Functions MD3 is yet another hash function designed by Ron Rivest. It had several flaws and never really made it out of the la...
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