Cryptology ePrint Archive: Report 2013/115

A Conditional Proxy Broadcast Re-Encryption Scheme Supporting Timed-Release

Kaitai Liang and Qiong Huang and Roman Schlegel and Duncan S. Wong and Chunming Tang

Abstract: To allow a delegator not only to delegate the keyword-controlled decryption rights of a broadcast encryption to a set of speci ed recipi- ents, but also to control when the decryption rights will be delegated, in this paper, for the rst time, we introduce a new notion called Timed- Release Conditional Proxy Broadcast Re-Encryption (TR-CPBRE). We also propose a concrete construction for TR-CPBRE which can be proven selective identity adaptive CCA secure under the (P; Q; f)-general de- cisional Die-Hellman exponent assumption, and chosen-time period chosen-ciphertext secure under the bilinear Die-Hellman assumption. When compared with the existing CPBRE and Timed-Release Proxy Re-Encryption (TR-PRE) schemes, our scheme achieves better eciency, and enables the delegator to make a ne-grained delegation of decryption rights to multiple delegatees.

Category / Keywords: timed-release encryption, unidirectional conditional proxy broadcast re-encryption, bilinear map.

Date: received 27 Feb 2013, last revised 5 May 2013

Contact author: kliang4-c at my cityu edu hk

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Version: 20130506:022616 (All versions of this report)

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