关键词: 个人健康记录（PHR）系统, 属性撤销, 属性权重, 属性基加密

Abstract: The users may dynamically enter or leave the Personal Health Record（PHR） system, so the realtime fine-grained attributes revocation is required and is more suitable for practical applications. In this paper, an improved weighted attribute-based encryption scheme with revocation is proposed. The proposed scheme not only has the function of out sourcing decryption, but also does fine-grained attributes revocation in time. By constructing the KEK tree, the proposed scheme updates key and cipher text timely to achieve fine-grained attributes revocation. In addition, based on the fact that the importance of the attributes is not considered in existing policy attributes ciphertext encryption schemes, the concept of weight attribute is adopted in the proposed scheme to make it more suitable for the PHR system. The security analysis and experimental results indicate that, compared with existing CP-ABE schemes, the proposed scheme resists the conspiracy attack, ensures the confidentiality of data, and guarantees the forward and backward security. In addition, the computational complexity of the propopsed scheme is decreased.

Key words: Personal Health Records（PHR） system, attribute revocation, weighted attribute, attribute-based encryption