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Efficiency Optimisation Of Tor Using Diffie-Hellman Chain

Authors:
Kun Peng

Keywords: TOR, efficient key exchange, Diffie-Hellman chain

Abstract:
Onion routing is the most common anonymous communication channel. Usually onion routing is specified through asymmetric cipher and thus is inefficient. In Tor (the second generation onion router), it is suggested to employ symmetric cipher to encrypt the packets in onion routing. Obviously, symmetric cipher is much more efficient than the asymmetric cipher employed in the original onion routing. However, whether this idea can really work depends on whether an efficient (both in computation and communication) key generation and exchange mechanism can be designed for the symmetric cipher to employ. The suggestion in Tor is simple and it is a direct employment of Diffie-Hellman handshake to generate the secret keys for the routers' symmetric cipher. In this paper we show that direct application of Diffie-Hellman handshake to implement key generation and exchange in onion routing is not efficient in communication as multiple instances of Diffie-Hellman handshake needs a lot of additional communication. Moreover, its efficiency improvement for the sender is not satisfactory. So we design a more advanced application of Diffie-Hellman key exchange technique, Diffie-Hellman chain. This new technique greatly saves a sender's cost and needs very few communication for Diffie-Hellman key exchange. With the efficiency improvement in this paper, Tor can be applied to communication networks with weaker computational capability and smaller communicational bandwidth.

Pages: 41 to 46

Copyright: Copyright (c) IARIA, 2011

Publication date: January 23, 2011

Published in: conference

ISSN: 2308-4413

ISBN: 978-1-61208-113-7

Location: St. Maarten, The Netherlands Antilles

Dates: from January 23, 2011 to January 28, 2011