A certificateless and KGA-secure searchable encryption scheme with constant trapdoors in smart city

Smart cities, as a typical application in the field of the Internet of Things, can combine cloud computing to realize the intelligent control of objects and process massive data. While cloud computing brings convenience to smart city services, a serious problem is ensuring that confidential data cannot be leaked to malicious adversaries. Considering the security and privacy of data, data owners transmit sensitive data in its encrypted form to cloud server, which seriously hinders the improvements of potential utilization and efficient sharing. Public key searchable encryption ensures that users can securely retrieve the encrypted data without decryption. However, most existing schemes cannot resist keyword guessing attacks or the size of trapdoors linearly increases with the number of data owners. In this work, by utilizing certificateless encryption and proxy re-encryption, we design an authenticated searchable encryption scheme with constant trapdoors. The designed scheme preserves the privacy of index ciphertexts and keyword trapdoors, and can resist keyword guessing attacks. In addition, data users can generate and upload trapdoors with lower computation and communication overheads. We show that the proposed scheme is suitable for smart city implementations and applications by experimentally evaluating its performance.