## Cryptology ePrint Archive: Report 2004/179

Identity Based Threshold Ring Signature

Sherman S.M. Chow and Lucas C.K. Hui and S.M. Yiu

Abstract: In threshold ring signature schemes, any group of $t$ entities spontaneously conscripting arbitrarily $n-t$ entities to generate a publicly verifiable $t$-out-of-$n$ signature on behalf of the whole group, yet the actual signers remain anonymous. The spontaneity of these schemes is desirable for ad-hoc groups such as mobile ad-hoc networks. In this paper, we present an identity based (ID-based) threshold ring signature scheme. The scheme is provably secure in the random oracle model and provides trusted authority compatibility. To the best of authors' knowledge, our scheme is the first ID-based threshold ring signature scheme which is also the most efficient (in terms of number of pairing operations required) ID-based ring signature scheme (when $t = 1$) and threshold ring signature scheme from pairings.

Category / Keywords: public-key cryptography / Threshold ring signature, identity-based signature, bilinear pairings, anonymity, spontaneity

Publication Info: ICISC 2004, To Appear

Date: received 24 Jul 2004, last revised 2 Feb 2005

Contact author: smchow at cs hku hk

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