Cryptology ePrint Archive: Report 2012/341

From Selective to Full Security: Semi-Generic Transformations in the Standard Model

Michel Abdalla and Dario Fiore and Vadim Lyubashevsky

Abstract: In this paper, we propose an efficient, standard model, semi-generic transformation of selective-secure (Hierarchical) Identity-Based Encryption schemes into fully secure ones. The main step is a procedure that uses admissible hash functions (whose existence is implied by collision-resistant hash functions) to convert any selective-secure \emph{wildcarded} identity-based encryption (WIBE) scheme into a fully secure (H)IBE scheme. Since building a selective-secure WIBE, especially with a selective-secure HIBE already in hand, is usually much less involved than directly building a fully secure HIBE, this transform already significantly simplifies the latter task. This black-box transformation easily extends to schemes secure in the Continual Memory Leakage (CML) model of Brakerski et al. (FOCS 2010), which allows us obtain a new fully secure IBE in that model. We furthermore show that if a selective-secure HIBE scheme satisfies a particular security notion, then it can be generically transformed into a selective-secure WIBE. We demonstrate that several current schemes already fit this new definition, while some others that do not obviously satisfy it can still be easily modified into a selective-secure WIBE.

Category / Keywords: public-key cryptography / identity based encryption, selective security

Publication Info: This is the full version of the paper that appeared at PKC 2012

Date: received 14 Jun 2012

Contact author: fiore at cs nyu edu

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Version: 20120622:195001 (All versions of this report)

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