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

3 victor sends peggy a random number e between 0 and

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Unformatted text preview: bits long. (Of course, there has been considerable progress in factoring since then.) If each user chooses his own n and publishes it in a public key file, they can dispense with the arbitrator. However, this RSA-like variant makes the scheme considerably less convenient. Fiat-Shamir Signature Scheme Turning this identification scheme into a signature scheme is basically a matter of turning Victor into a hash function. The primary benefit of the Fiat-Shamir digital signature scheme over RSA is speed: Fiat-Shamir requires only 1 percent to 4 percent of the modular multiplications of RSA. For this protocol, we’ll bring back Alice and Bob. 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 ----------- The setup is the same as the identification scheme. Choose n to be the product of two large primes. Generate the public key, v1, v2,..., vk, and the private key, s1, s2,..., sk, such that si = sqrt (vi-1) mod n. (1) Alice picks t random integers between 1 and n: r1, r2,..., rt, and computes x1, x2,..., xt such that xi = ri2 mod n. (2) Alice hashes the concatenation of the message and the string of xis to generate a bit stream: H(m, x1, x2,..., xt). She uses the first k * t bits of this string as values of bij, where i goes from 1 to t, and j goes from 1 to k. (3) Alice computes y1, y2,..., yt, where yi = ri * (s1bi1 * s2bi2 *...* skbik) mod n (For each i,...
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