Security analysis and improvement of an anonymous attribute-based proxy re-encryption

Abstract

The ciphertext-policy attribute-based proxy re-encryption (CP-AB-PRE) is a flexible proxy re-encryption (PRE), which makes the encryptor control its encrypted data at a fine-grained level and update the access policy. However, most of constructions focuses only on the data security, rather than on user privacy protection. In order to protect users’ attribute privacy, recently, a novel secure CP-AB-PRE named anonymous CP-AB-PRE was first proposed by Zhang et al. However, we found that their scheme fails to achieve anonymity, which means that their scheme cannot realize users’ attribute privacy protection. In order to remedy this security gap, a novel anonymous CP-AB-PRE scheme is proposed, which can protect user attribute privacy by hiding the access policy. Theoretical analysis and simulation results demonstrate that our proposed scheme is secure and efficient.