A Pairing-Free Public Key Encryption with Keyword Searching for Cloud Storage Services

Abstract

Although cloud computing provides a platform for numerous adorable applications, users are still detracts from fully utilizing its services, for fear of jeopardizing data confidentiality and privacy by surrendering maintenance and management roles in the hands of cloud service providers (CSPs). A natural resolution to users’ concern is employing cryptographic measures which allow searching for a particular keyword flexibly stored in the cloud without divulging data privacy to any unwanted party even the CSP itself. Already there has been many keyword searchable encryption researches done, but they mostly bear a weakness of offline keyword guessing attack, besides they are based on the heavier pairing computation. We therefore devise an efficient public key encryption with keyword search (PEKS) protocol that is pairing-free and is resilient against offline keyword guessing attack for cloud storage services. Our basic construction is based on the Diffie-Hellman problem and the El Gamal encryption scheme to achieve a secure channel-free public key encryption with keyword searching (SCF-PEKS). In this design a user sends a key allowing the CSP to only identify words containing a specific keyword and return search results and learn nothing else besides.