Cryptology ePrint Archive: Report 2007/082

Deniable Authentication on the Internet

Shaoquan Jiang

Abstract: Deniable authentication is a technique that allows one party to send messages to another while the latter can not prove to a third party the fact of communication. In this paper, we first formalize a natural notion of deniable security and naturally extend the basic authenticator theorem by Bellare et al. \cite{bck98} to the setting of deniable authentication. Of independent interest, this extension is achieved by defining a deniable MT-authenticator via a game. This game is essentially borrowed from the notion of universal composition \cite{can01} although we do not assume any result or background about it. Then we construct two deniable MT-authenticators: uncontrollable random oracle based and the PKI based, both of which are just 3-round protocols. The second construction assumes the receiver owns a secret key. Such a setup assumption is very popular in the real world. (Without this assumption), all the previous protocols do not have a widely satisfiable performance when applied in the Internet-like environment. Finally, as our application, we obtain key exchange protocols that is deniably secure in the real world.

Category / Keywords: cryptographic protocols / Deniable Authentication, Privacy

Publication Info: Unpublished

Date: received 3 Mar 2007

Contact author: jiangshq at math ucalgary ca

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Version: 20070305:183104 (All versions of this report)

Short URL: ia.cr/2007/082