Multi-Recipient encryption with keyword search without pairing for cloud storage

With the rapid development of cloud computing technology and communication technology, cloud storage has become a tool used by people in daily life. Cloud storage service enables users to outsource data to cloud servers and retrieve desired document efficiently. Individual privacy in outsource data are very sensitive and should be prevented from any leakage. Public-key encryption with keyword search (PEKS) scheme resolves this tension, while public-key authentication encryption with keyword search (PAEKS) scheme improve its keyword guessing attacks problem potentially. Whereas, the loss of keyword privacy, the limitation of single user interaction and low efficiency make PEKS/PAEKS schemes far from enough in practical applications.In this paper, we develop a multi-recipient public key encryption scheme with keyword search without pairing (MREKS) for cloud storage under public key infrastructure. The proposed scheme has the merits of supporting multi-recipient keyword search way as well as requiring no expensively bilinear pairing operations under standard model. We present a concrete and efficient construction of MREKS, and prove its security based on discrete logarithm assumptions. Furthermore, we embed the algorithm of data plaintext encryption and decryption into the scheme, which makes the scheme more practical. We show that our scheme enjoys much more efficiency than previous PEKS/PAEKS scheme in the simulation experiment, especially the keyword encryption is optimized by 79.5%.