## Cryptology ePrint Archive: Report 2007/068

Efficient Hierarchical Identity Based Signature in the Standard Model

Man Ho Au and Joseph K. Liu and Tsz Hon Yuen and Duncan S. Wong

Abstract: The only known constructions of Hierarchical Identity Based Signatures that are proven secure in the strongest model without random oracles are based on the approach of attaching certificate chains or hierarchical authentication tree with one-time signature. Both construction methods lead to schemes that are somewhat inefficient and leave open the problem of efficient direct construction. In this paper, we propose the first direct construction of Hierarchical Identity Based Signature scheme that is proven under the strongest model without relying on random oracles and using more standard $q$-SDH assumption. It is computationally efficient and the signature size is constant.

When the number of hierarchical level is set to be one, our scheme is a normal identity based signature scheme. It enjoys the shortest size in public parameters and signatures when compare with others in the literature, with the same security level.

Category / Keywords: public-key cryptography / Identity Based Signature

Date: received 21 Feb 2007, withdrawn 1 Nov 2007

Contact author: ksliu9 at gmail com

Available format(s): (-- withdrawn --)

Short URL: ia.cr/2007/068

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