Public‐key encryption with keyword search secure against continual memory attacks

Continual memory attacks, inspired by recent realistic physical attacks, have broken many cryptographic schemes that were considered secure in traditional cryptography model. In this paper, we consider the continual memory leakage resilience in public‐key encryption with keyword search scheme (PEKS). We give the definition of continual memory leakage resilience security for PEKS, which allows continual secret key leakage in the trapdoor generation algorithm rather than leakage of trapdoor itself. We believe that the definition is more suitable for practical PEKS scenario. To construct a concrete PEKS scheme secure against continual memory attacks, we firstly obtain a continual master‐key leakage‐resilient anonymous identity‐based encryption (IBE) scheme by applying the generic tool provided by Lewko et al. to a fully secure anonymous IBE scheme that comes from the fully secure anonymous hierarchical identity‐based encryption (HIBE) scheme of De Caro and colleagues. Then, we transform our continual master‐key leakage‐resilient anonymous IBE scheme to a PEKS scheme using the generic Anonymous IBE‐to‐PEKS transformation and prove its continual leakage‐resilient security. Copyright © 2016 John Wiley & Sons, Ltd. In this paper, we propose a method of constructing public‐key encryption with keyword search scheme (PEKS) secure against continual memory attacks which allow the adversary to continually obtain secret key leakage in the trapdoor generation algorithm. Our method applies identity‐based encryption(IBE)‐to‐PEKS transformation to a master‐key leakage‐resilient anonymous IBE scheme. Also, we give a concrete master‐key leakage‐resilient anonymous IBE scheme which can be used to construct a concrete PEKS scheme secure against continual memory attacks.