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

If eve ever gets two messages signed using the same k

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Unformatted text preview: method for generating the two primes, p and q, where q divides p – 1. The prime p is L bits long, between 512 and 1024 bits long, in some multiple of 64 bits. The prime q is 160 bits long. Let L – 1 = 160n + b, where L is the length of p, and n and b are two numbers and b is less than 160. Table 20.2 DSA Speeds for Different Modulus Lengths with a 160-bit Exponent (on a SPARC II) 512 bits Sign 0.20 sec Verify 0.35 sec 768 bits 0.43 sec 0.80 sec 1024 bits 0.57 sec 1.27 sec Table 20.3 Comparison of RSA and DSA Computation Times DSA with Common p, q, g Off-card (P) 4 sec 4 sec .03 sec 10 sec DSA Global Computations Key Generation Precomputation Signature Verification Off-card (P) 14 sec 14 sec .03 sec 16 sec RSA N/A Off-card (S) N/A 15 sec 1.5 sec 1–5 sec off-card 1–3 sec off-card (P) (P) Off-card computations were performed on an 80386 33 mHz, personal computer. (P) indicates public parameters off-card and (S) indicates secret parameters off-card. Both algorithms use a 512-bit modulus. 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 ----------- (1) Choose an arbitrary sequence of at least 160 bits and call it S. Let g be the length of S in bits. (2) Compute U = SHA(S) • SHA ((S + 1) mod 2g), where SHA is the Secure Hash Algorithm (see Section 18.7). (3) Form q by setting the most significant bit and the least significant bit of U to 1. (4) Check whether q is prime. (5) If q is...
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