Public-Key Authenticated Encryption With Keyword Search Supporting Constant Trapdoor Generation and Fast Search

To improve the quality of medical care and reduce unnecessary medical errors, electronic medical records (EMRs) are widely applied in hospital information systems. However, rapidly increasing EMRs bring heavy storage burden to hospitals. Professional data management service provided by cloud server can save the hospital local storage, and meanwhile, realize EMRs sharing among external researchers. However, the risk of leaking information of patients discourages hospitals to outsource patients' EMRs to the remote cloud server. In this paper, a secure and efficient cloud storing and sharing method can be achieved by applying the proposed public key authenticated encryption with ciphertext update and keyword search (PAUKS). The proposed PAUKS scheme enables EMRs to be encrypted and queried without decryption, and is secure against inside keyword guessing attacks. Compared with the recently proposed PAEKS in literature, the PAUKS scheme enjoys smaller computation and communication overheads. The required number of trapdoors per query is constant in PAUKS scheme, instead of the linearly expanding as the number of senders increases in PAEKS. Furthermore, an inverted index can be built safely in PAUKS scheme to accelerate the query procedure. Experiment results show that our PAUKS scheme owns a comparable running overhead, but enjoys a higher query efficiency after ciphertexts update.