Continuous Leakage-resilient and Hierarchical Identity-based Online/Offline Encryption

By dividing encryption as online and offline stages, the online/offline encryption schemes are very suitable to lightweight equipment. For the offline stage, high-performance equipment is used for complex preprocessing calculation, and the online stage the lightweight devices only make some simple calculations. In addition, side channel attacks can disclose some secret information of the cryptosystem, which leads to the destruction of the security of the cryptography schemes. Most of the online/offline identity -based encryption schemes cannot resist side channel attacks. The paper proposes a concrete hierarchical identity-based and online/offline encryption scheme that can resist continuous leakage of secret key. By the dual system encryption technology, we prove that the given scheme is fully secure. Through key updation technology, our proposed scheme resists continual leakage of private key. The relative leakage rate of the private key can reach 1/3. In addition, the presented scheme has the hierarchical function which effectively solves the problem of heavy load in a single key generation center. The given scheme is suitable for applications in distributed environment.