Leakage-Resilient Key-Aggregate Cryptosystem with Auxiliary Input

Key aggregate cryptosystem is a new cryptographic primitive that one can aggregate any set of secret keys to a single key, which has the power of all the secret keys being aggregated. The data owner can send the aggregate key to any authorized decryptors. Key aggregate cryptosystem can realize conveniently, flexibly and securely sharing data in cloud storage. However, when the key aggregate cryptosystem is deployed in cloud storage, it is easily to encounter many side-channel attacks. Thus, we design a leakage resilient key aggregate cryptosystem with auxiliary input, in which no matter how many leaked bits the attacker obtains from the aggregate key, it still cannot recover the master secret key. We proved that our scheme is auxiliary input CPA secure based on Chu et al.'s scheme.