Douglas Stebila
Towards a provably secure DoS-resilient key exchange protocol with perfect forward secrecy
Abstract
Just Fast Keying (JFK) is a simple, efficient and secure key exchange protocol proposed by Aiello et al. (ACM TISSEC, 2004). JFK is well known for its novel design features, notably its resistance to denial-of-service (DoS) attacks. Using Meadows' cost-based framework, we identify a new DoS vulnerability in JFK. The JFK protocol is claimed secure in the Canetti-Krawczyk model under the Decisional Diffie-Hellman (DDH) assumption. We show that security of the JFK protocol, when re-using ephemeral Diffie-Hellman keys, appears to require the Gap Diffie-Hellman (GDH) assumption in the random oracle model. We propose a new variant of JFK that avoids the identified DoS vulnerability and provides perfect forward secrecy even under the DDH assumption, achieving the full security promised by the JFK protocol.
Keywords: denial of service, Meadows' cost-based framework, Just Fast Keying, client puzzles, key agreement, perfect forward secrecy
Reference
Lakshmi Kuppusamy, Jothi Rangasamy, Douglas Stebila, Colin Boyd, Juan González Nieto. Towards a provably secure DoS-resilient key exchange protocol with perfect forward secrecy. In Daniel J. Bernstein, Sanjit Chatterjee, editors, Proc. 12th International Conference on Cryptology in India (INDOCRYPT) 2011, LNCS, vol. 7107, pp. 379-398. Springer, December 2011. © Springer.
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Funding
This research was supported by:- Australia–India Strategic Research Fund (AISRF) project TA020002