Unformatted text preview: ustavus Simmons [1458,1459,1460], uses the OngSchnorrShamir identification scheme (see Section 20.5). As in the original scheme, the sender (Alice) chooses a public modulus, n, and a private key, k, such that n and k are relatively prime. Unlike the original scheme, k is shared between Alice and Bob, the recipient of the subliminal message. The public key is calculated: h = k2 mod n If Alice wants to send the subliminal message M by means of the innocuous message M', she first confirms that M' and n are relatively prime, and that M and n are relatively prime. Alice calculates S1 = 1/2 * ((M' /M + M)) mod n S2 = k/2 * ((M' /M  M)) mod n Together, the pair, S1 and S2, is the signature under the traditional OngSchnorrShamir scheme and the carrier of the subliminal message. Walter the warden (remember him?) can authenticate the message as described by the OngSchnorrShamir signature scheme, but Bob can do better. He can authenticate the message (it is always possible that Walter can make his own messages). He confirms that S12  S2 2/k2 a M' (mod n) If the message is authentic, the receiver can recover the subliminal message using this formula: M = M'/(S1 + S2 k1) mod n This works, but remember that the basic OngSchnorrShamir has been broken. 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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