Distributed private-key generators for identity-based cryptography

  • Authors:
  • Aniket Kate;Ian Goldberg

  • Affiliations:
  • Cheriton School of Computer Science, University of Waterloo, Canada;Cheriton School of Computer Science, University of Waterloo, Canada

  • Venue:
  • SCN'10 Proceedings of the 7th international conference on Security and cryptography for networks
  • Year:
  • 2010

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Abstract

An identity-based encryption (IBE) scheme can greatly reduce the complexity of sending encrypted messages. However, an IBE scheme necessarily requires a private-key generator (PKG), which can create private keys for clients, and so can passively eavesdrop on all encrypted communications. Although a distributed PKG has been suggested as a way to mitigate this key escrow problem for Boneh and Franklin's IBE scheme, the security of this distributed protocol has not been proven. Further, a distributed PKG has not been considered for any other IBE scheme. In this paper, we design distributed PKG setup and private key extraction protocols for three important IBE schemes; namely, Boneh and Franklin's BF-IBE, Sakai and Kasahara's SK-IBE, and Boneh and Boyen's BB1-IBE. We give special attention to the applicability of our protocols to all possible types of bilinear pairings and prove their IND-ID-CCA security in the random oracle model against a Byzantine adversary. Finally, we also perform a comparative analysis of these protocols and present recommendations for their use.