Fine-grained conditional proxy re-encryption and application

Abstract

Conditional proxy re-encryption (CPRE) enables delegation of decryption rights, and is useful in many applications. In this paper, we present a ciphertext-policy attribute based CPRE scheme, together with a formalization of the primitive and its security proof. We further propose applying the scheme for fine-grained encryption of cloud data. This application well implements the idea of cloud-enabled user revocation, offering an alternative yet more feasible solution to the user revocation issue when using attribute based encryption over cloud data. Features of the application include little cost in case of user revocation, and high user-side efficiency when users access cloud data.