Secure and Efficient Data-Sharing in Clouds

Cloud storage allows users to access and store data in clouds over the internet, and provides a cheap and reliable solution for users with the demand of data storage. One of the main challenges in public cloud storage is to protect the security of data and to efficiently share data. In the past years, several papers in the literature have used proxy re-encryption (PRE) to address this challenge, where the performance of the underlying PRE scheme is very critical to the overall performance of the cloud storage. In this paper, we dedicate to design a secure and practical PRE scheme, which is CCA secure under the computational Diffie-Hellman (CDH) assumption in the random oracle model. We evaluate the efficiency of our scheme both in theoretical comparisons with related schemes and in implementations at several security levels using the recommended elliptic curve parameters from NIST, and the results indicate that our scheme can be practical in cloud-based data-sharing.