lmprovement of A Searchable Keyword Public Key Encryption Scheme in Cloud Storage

Abstract In big data era, more and more people store their data in some outsourced cloud, but this brings up a problem that how to keep some important and sensitive data from revealing to the curious cloud and malicious ones who aim to steal information. In this case, public-key encryption with keyword search (PEKS) has become an indispensable branch in cryptography. Many great works have been done to contribute this field since then. In 2018, Wu et al (2018) came up with an efficient and secure searchable public key encryption scheme with privacy protection for cloud storage. However, in this paper, we proved that their scheme is not secure under indistinguishability against keyword guessing attack (IND-KGA) by giving two ways to break their scheme. Then we proposed an improved scheme to make it secure and more efficient in some way. And we proved that the proposed scheme is secure under IND-KGA and indistinguishability against chosen keyword attack game (IND-CKA). Finally, in terms of security performance for restricted device data collection, our trapdoor generation algorithm has more advantages.