Cryptology ePrint Archive: Report 2009/219

Strongly Secure Certificateless Key Agreement

Georg Lippold and Colin Boyd and Juan Gonz\'{a}lez Nieto

Abstract: We introduce a formal model for certificateless authenticated key exchange (CL-AKE) protocols. Contrary to what might be expected, we show that the natural combination of an ID-based AKE protocol with a public key based AKE protocol cannot provide strong security. We provide the first one-round CL-AKE scheme proven secure in the random oracle model. We introduce two variants of the Diffie-Hellman trapdoor introduced by \cite{DBLP:conf/eurocrypt/CashKS08}. The proposed key agreement scheme is secure as long as each party has at least one uncompromised secret. Thus, our scheme is secure even if the key generation centre learns the ephemeral secrets of both parties.

Category / Keywords: cryptographic protocols / public key cryptography, key exchange, certificateless, key agreement, random oracle model, eCK, Bilinear Diffie-Hellman Trapdoor, proof

Publication Info: Pairing 2009 accepted paper

Date: received 18 May 2009, last revised 27 Jul 2010

Contact author: g lippold at qut edu au

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Version: 20100727:160230 (All versions of this report)

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