Title: Hierarchical identity-based encryption without key delegation in decryption

Authors: Song Luo; Zhong Chen

Addresses: College of Computer Science and Engineering, Chongqing University of Technology, Chongqing 400054, China ' Institute of Software, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China; Key Laboratory of High Confidence Software Technologies, Ministry of Education, Peking University, Beijing 100871, China

Abstract: Hierarchical Identity-Based Encryption (HIBE) is a generalisation of Identity-Based Encryption (IBE) which mirrors an organisational hierarchy. However, when the user decrypts a ciphertext encrypted to a hierarchical identity, he/she should know the exact hierarchical identity in order to run the delegate algorithm to get the secret key corresponding to the target hierarchical identity if the hierarchical identity linked with his/her key is a prefix of the target hierarchical identity. In this paper, we consider a new concept called HIBE without key delegation in decryption. In such HIBE systems, the user can decrypt the ciphertext directly without running the delegate algorithm even if his hierarchical identity is only a prefix of the target hierarchical identity. We present two HIBE systems, which are proven secure in the standard model under the decision BDH and l-BDHE assumptions, respectively. Both systems have the same decryption efficiency in pairing, compared with BB₁-HIBE system and BBG-HIBE system, respectively.

Keywords: hierarchical IBE; identity-based encryption; HIBE; key delegation; decryption; standard model; organisational hierarchy; ciphertext; security.

DOI: 10.1504/IJGUC.2014.060182

International Journal of Grid and Utility Computing, 2014 Vol.5 No.2, pp.71 - 79

Received: 25 Aug 2012
Accepted: 23 Sep 2012
Published online: 29 Oct 2014 *

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