A Searchable Encryption with Forward/Backward Security and Constant Storage

Dynamic searchable encryption satisfies users’ needs for ciphertext retrieval on semi-trusted servers, while allowing users to update server-side data. However, cloud servers with dynamically updatable data are vulnerable information abuse and file injection attacks, current public key-based dynamic algorithms often complicated in construction high computational overhead, which is not efficient practical applications. In addition, the client’s storage costs grow linearly number of keywords database, creating a new bottleneck when size keyword set large. To solve above problems, scheme that uses double-layer structure, satisfying forward backward security, proposed. The structure maintains constant client-side cost guaranteeing security further reduces algorithm overhead by avoiding bilinear pairings decryption operations. analysis results show more advantageous terms efficiency than existing under key cryptosystem. It also suitable big communication environment.