Identity-based threshold key-insulated encryption without random oracles

  • Authors:

  • Jian Weng;Shengli Liu;Kefei Chen;Dong Zheng;Weidong Qiu

  • Affiliations:

  • Dept. of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China;Dept. of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China and State Key Laboratory of Information Security, Institute of Software, Chinese Academy of Sciences, ...;Dept. of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China;Dept. of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China;School of Information Security Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China

  • Venue:
  • CT-RSA'08 Proceedings of the 2008 The Cryptopgraphers' Track at the RSA conference on Topics in cryptology
  • Year:
  • 2008

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Abstract

With more and more cryptosystems being deployed on insecure environments such as mobile devices, key exposures appear to be unavoidable. This is perhaps the most devastating attack on a cryptosystem, since it typically means that security is entirely lost. This problem is especially hard to tackle in identity-based encryption (IBE) settings, where the public key is determined as a user's identity and is not desirable to be changed. In this paper, we extend Dodis et al.'s key-insulation idea and present a new paradigm named threshold key-insulation. The new paradigm not only greatly enhances the security of the system, but also provides flexibility and efficiency. To deal with the key-exposure problem in IBE settings, we further propose an identity-based threshold key-insulated encryption (IBTKIE) scheme. The proposed scheme is proved to be semantically secure without random oracles.