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

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Unformatted text preview: r, rB, and sends Trent rB3 mod n (4) Trent uses his private key to recover rA and rB. He sends Alice rA• rB (5) Alice calculates (rA• rB) • rA = rB She uses this rB to communicate securely with Bob. This protocol looks good, but it has a horrible flaw. Carol can listen in on step (3) and use that information, with the help of an unsuspecting Trent and another malicious user (Dave), to recover rB [1472]. (1) Carol chooses a random number, rC, and sends Trent rB3rC3 mod n (2) Trent tells Dave that someone wants to exchange a key with him. (3) Dave chooses a random number, rD, and sends Trent rD3 mod n (4) Trent uses his private key to recover rC and rD. He sends Carol (rBrC) mod n• rD (5) Dave sends rD to Carol. (6) Carol uses rC and rD to recover rB. She uses rB to eavesdrop on Alice and Bob. This is not good. 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 ----------- Chapter 23 Special Algorithms for Protocols 23.1 Multiple-Key Public-Key Cryptography This is a generalization of RSA (see Section 19.3) [217,212]. The modulus, n, is the product of two primes, p and q. However, instead of choosing e and d such that ed a 1 mod ((p - 1)(q - 1)), choose t keys, Ki, such that K1 * K2 *...* Kt a 1 mod ((p - 1)(q - 1)) Since MK1*K2*...*Kt = M this is a multiple-key scheme as described in Section 3.5. If, for example, there are five keys, a message encrypt...
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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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