Achieving Leakage Resilience through Dual System Encryption

In this work, we show that strong leakage resilience for cryptosystems with advanced functionalitiescan be obtained quite naturally within the methodology of dual system encryption, recently introducedby Waters. We demonstrate this concretely by providing fully secure IBE, HIBE, and ABE systems whichare resilient to bounded leakage from each of many secret keys per user, as well as many master keys.This can be realized as resilience against continual leakage if we assume keys are periodically updated andno (or logarithmic) leakage is allowed during the update process. Our systems are obtained by applying asimple modification to previous dual system encryption constructions: essentially this provides a generictool for making dual system encryption schemes leakage-resilient.