¹ Department of Electronic Information Xianyang Vocational Technical College, 712000, P. R. China
² Key Laboratory of Information and Network Security Engineering University of Chinese Armed Police Force, 710086, P. R. China

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Abstract—In proxy re-encryption, a proxy can transform a ciphertext computed under A’s public key into one that can be opened under B’s decryption key. In this paper, we focus on the the research of proxy re-encryption in the identity based setting. In particular, we are interested in constructing PRE schemes basically based on standardized IBE schemes, such as BB2 IBE, SK IBE. We construct the first IBPRE scheme based on BB2 IBE, the first IBPRE scheme based on SK IBE with the help of PKG. Concretely, we allow PKG to generate the re-encryption keys between the Delegator and Delegatee by using its master-key.We also prove their security in the corresponding security models, by introducing some novel techniques which maybe have independent interest. At a first look, involving PKG in generating re-encryption keys seems unreasonable, which will greatly increase PKG’s workload. But we challenge this traditional view. Firstly, in an IBE system, typically small self-organizations like corporation etc, the demand on proxy re-encryption between any two users is not very often. Thus PKG’s workload will be greatly lower than our original anticipation. Secondly, these schemes can easily achieve master secret secure property, while the previous PRE schemes can not easily achieve, and even non-transferable property, while all the previous PRE schemes can not achieve. These properties are very important for the wide adaptation of IBPRE and PRE.

Index Terms—Cryptography, Identity based proxy reencryption, PKG, BB2 IBE, SK IBE, Security proof.

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Cite: Jindan Zhang, Xu An Wang and Xiaoyuan Yang, " Identity Based Proxy Re-encryption Based on BB2 and SK IBE with the Help of PKG," Journal of Computers vol. 8, no. 5, pp. 1230-1239, 2013.