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

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Unformatted text preview: tication Security Service (DASS) protocols, developed at Digital Equipment Corporation, also provide for mutual authentication and key exchange [604,1519,1518]. Unlike the previous protocols, DASS uses both public-key and symmetric cryptography. Alice and Bob each have a private key. Trent has signed copies of their public keys. (1) Alice sends a message to Trent, consisting of Bob’s name. B (2) Trent sends Alice Bob’s public key, KB, signed with Trent’s private key, T. The signed message includes Bob’s name. ST(B,KB) (3) Alice verifies Trent’s signature to confirm that the key she received is actually Bob’s public key. She generates a random session key, and a random public-key/private-key key pair: KP. She encrypts a timestamp with K. Then she signs a key lifetime, L, her name, and KP with her private key, KA. Finally, she encrypts K with Bob’s public key, and signs it with KP. She sends all of this to Bob. EK(TA),SKA(L,A,KP),SKP(EKB(K)) (4) Bob sends a message to Trent (this may be a different Trent), consisting of Alice’s name. A (5) Trent sends Bob Alice’s public key, signed in Trent’s private key. The signed message includes Alice’s name. ST(A,KA) (6) Bob verifies Trent’s signature to confirm that the key he received is actually Alice’s public key. He then verifies Alice’s signature and recovers KP. He verifies the signature and uses his private key to recover K. Then he decrypts TA to make sure this is a current message. (7) If mutual authentication is required, Bob encrypts a new timestamp with K, and sends it to Alice. EK(TB) (8) Alice decrypts TB with K to make sure that the message is current. SPX, a product by DEC, is based on DASS. Additional information can be found in [34]. 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 me...
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This note was uploaded on 10/18/2010 for the course MATH CS 301 taught by Professor Aliulger during the Fall '10 term at Koç University.

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