Cloud based data sharing with fine-grained proxy re-encryption

Conditional proxy re-encryption (CPRE) enables fine-grained delegation of decryption rights, and has many real-world applications. In this paper, we present a ciphertext-policy attribute based CPRE scheme, together with a formalization of the primitive and its security analysis. We demonstrate the utility of the scheme in a cloud deployment, which achieves fine-grained data sharing. This application implements cloud server-enabled user revocation, offering an alternative yet more efficient solution to the user revocation problem in the context of fine-grained encryption of cloud data. High user-side efficiency is another prominent feature of the application, which makes it possible for users to use resource constrained devices, e.g., mobile phones, to access cloud data. Our evaluations show promising results on the performance of the proposed scheme.