## Cryptology ePrint Archive: Report 2006/368

Practical Hierarchical Identity Based Encryption and Signature schemes Without Random Oracles

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

Abstract: In this paper, we propose a Hierarchical Identity Based Encryption scheme that is proven secure under the strongest model of \cite{BonehFr01} directly, without relying on random oracles. The size of the ciphertext is a constant while the size of public parameters is independent to the number of bit representing an identity. It is the first in the literature to achieve such a high security level and space efficiency at the same time. In addition, we also propose the first Hierarchical Identity Based Signature scheme that is proven under the strongest model without relying on random oracles and using more standard $q$-SDH assumption. Similar to the proposed encryption scheme, the space complexity of the signature and public parameters are as efficient as the proposed encryption scheme.

Category / Keywords: public-key cryptography / HIBE, HIBS, Without Random Oracle

Date: received 26 Oct 2006, last revised 4 Dec 2006

Contact author: liu at cs bris ac uk

Available format(s): PDF | BibTeX Citation

Short URL: ia.cr/2006/368

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