Unformatted text preview: a message with her identity and the timestamp, encrypts it in K, and sends it to Bob. Alice also sends Bob the message encrypted in Bob’s key from Trent. EK(A,T),EB(T,L,K,A) (4) Bob creates a message consisting of the timestamp plus one, encrypts it in K, and sends it to Alice. EK(T + 1) This protocol works, but it assumes that everyone’s clocks are synchronized with Trent’s clock. In practice, the effect is obtained by synchronizing clocks to within a few minutes of a secure time server and detecting replays within the time interval. Neuman-Stubblebine
Whether by system faults or by sabotage, clocks can become unsynchronized. If the clocks get out of sync, there is a possible attack against most of these protocols . If the sender’s clock is ahead of the receiver’s clock, Mallory can intercept a message from the sender and replay it later when the timestamp becomes current at the receiver’s site. This attack is called suppress-replay and can have irritating consequences. 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)
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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----------- This protocol, first presented in  and corrected in  attempts to counter the suppress-replay attack. It is an enhancement to Yahalom and is an excellent protocol. (1) Alice concatenates her name and a random number and sends it to Bob. A,RA (2) Bob concatenates Alice’s...
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