Forward-Secure hierarchical predicate encryption

  • Authors:
  • Juan Manuel González Nieto;Mark Manulis;Dongdong Sun

  • Affiliations:
  • Queensland University of Technology, Brisbane, QLD, Australia;Department of Computer Science, University of Surrey, United Kingdom;Queensland University of Technology, Brisbane, QLD, Australia

  • Venue:
  • Pairing'12 Proceedings of the 5th international conference on Pairing-Based Cryptography
  • Year:
  • 2012

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Abstract

Secrecy of decryption keys is an important pre-requisite for security of any encryption scheme. Forward Security (FS) reduces damage from compromised keys by guaranteeing confidentiality of messages that were encrypted prior to the compromise event. In this paper we introduce FS to the powerful setting of Hierarchical Predicate Encryption (HPE), proposed by Okamoto and Takashima (Asiacrypt 2009). Our FS-HPE scheme guarantees forward security for plaintexts and for attributes that are hidden in HPE ciphertexts. It further allows delegation of decrypting abilities at any point in time, independent of FS time evolution. It realizes zero-inner-product predicates and is proven adaptively secure under standard assumptions. As the "cross-product" approach taken in FS-HIBE is not directly applicable to the HPE setting, our construction resorts to techniques that are specific to existing HPE schemes and extends them with what can be seen as a reminiscent of binary tree encryption from FS-PKE.