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Unformatted text preview: being created. The fix to this problem is to hash the Randseed array before storing it, perhaps by just calling genrand(). When the system reboots, you read in the seed file, pass it to churnrand(), then promptly destroy it. Unfortunately, this does not deal with the threat of someone stealing the seed file between reboots and using it to guess future values of the genrand() function. I see no solution to this problem other than to wait until enough external random events have taken place after a reboot before allowing genrand() to produce results. 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 © 19962000 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)
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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:
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 Chapter 18 OneWay Hash Functions
18.1 Background
A oneway hash function, H(M), operates on an arbitrarylength preimage message, M. It returns a fixedlength hash value, h. h = H(M), where h is of length m Many functions can take an arbitrarylength input and return an output of fixed length, but oneway hash functions have additional characteristics that make them oneway [1065]: Given M, it is easy to compute h. Given h, it is hard to compute M such that H(M)= h. Given M, it is hard to find another message, M’, such that H(M) = H(M’). If Mallory could do the hard things, he would undermine the security of every protocol that uses the oneway hash function. The whole point of the oneway hash function is to provide a “fingerprint” of M that is unique. If Alice signed M...
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 Fall '10
 ALIULGER
 Cryptography

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