Public key encryption resilient to leakage and tampering attacks

In this work, we investigate how to protect public key encryption from both key-leakage attacks and tampering attacks. First, we formalize the notions of chosen ciphertext (CCA) security against key-leakage and tampering attacks. To this goal, we then introduce the concept of key-homomorphic hash proof systems and present a generic construction of public key encryption based on this new primitive. Our construction, compared with previous works, realizes leakage-resilience and tampering-resilience simultaneously but completely independently, so it can tolerate a larger amount of bounded-memory leakage and be instantiated with more flexibility. Moreover, it allows for an unbounded number of affine-tampering queries, even after the challenge phase. With slight adaptations, our construction also achieves CCA security against subexponentially hard auxiliary-input leakage attacks and a polynomial of affine-tampering attacks. Thus, to the best of our knowledge, we get the first public key encryption scheme secure against both auxiliary input leakage attacks and tampering attacks. (C) 2017 Elsevier Inc. All rights reserved.