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

Z shmuley and kevin mccurley studied a variant of the

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Unformatted text preview: s, J. Now, she wants to prove to Victor that those credentials are hers. To do this, she has to convince Victor that she knows B. Here’s the protocol: (1) Peggy picks a random integer r, such that r is between 1 and n - 1. She computes T = rv mod n and sends it to Victor. (2) Victor picks a random integer, d, such that d is between zero and v 1. He sends d to Peggy. (3) Peggy computes D = rBd mod n, and sends it to Victor. (4) Victor computes T´ = DvJd mod n. If T a T´ (mod n), then the authentication succeeds. The math isn’t that complex: T´ = DvJd = (rBd)vJd = rvBdvJd = rv(JBv)d = rv a T (mod n) since B was constructed to satisfy JBv a 1 (mod n) 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 ----------- Guillou-Quisquater Signature Scheme This identification can be converted to a signature scheme, also suited for smart-card implementation [671,672]. The public and private key setup is the same as before. Here’s the protocol: (1) Alice picks a random integer r, such that r is between 1 and n - 1. She computes T = rv mod n. (2) Alice computes d = H(M,T), where M is the message being signed and H(x) is a one-way hash function. The d produced by the hash function must be between 0 and v - 1 [1280]. If the output of the hash function is not within this range, it must be reduced modulo v. (3) Alice computes D = rBd mod n. The signature consists of the message, M, the two calculated values, d and D...
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