中文摘要：

随着云计算的发展,越来越多的用户在使用个人健康记录（PHR）云管理系统,由于PHR包含了患者的隐私信息,因此一般在将PHR上传到云平台之前会先对其进行加密。基于比较的加密（CBE）在基于属性的访问策略中实现了时间比较,然而CBE加密时间与访问策略中的属性数目线性增长,从而导致其开销过大;同时,方案难以实时撤销用户的访问权限。该文提出支持用户撤销的细粒度访问控制（FGUR）方案,通过将属性层次引入到CBE中,同时结合广播密文策略的基于属性加密（BCP-ABE）,高效地实现PHR云管理系统中的细粒度访问控制及用户实时撤销。实验结果表明,与CBE相比,FGUR方案在加密开销和动态访问权限方面具有更好的性能。

英文摘要：

With the development of cloud computing, more and more users employ cloud-based Personal Health Record （PHR） systems. The PHR is correlated with patient privacy, thus existing research suggests to encrypt PHRs before outsourcing. Comparison-Based Encryption （CBE） realizes time comparison in attribute-based access policy, however, the time for encryption is linearly with the cost of the scheme is extensive; besides, the scheme is the number of attributes in the access policy. Therefore difficult to revoke the user＇s access privileges in real time To realize efficiently a fine-grained access control and user revocation for PHRs in clouds, a Fine-Grained access control with User Revocation （FGUR） scheme is proposed by incorporating Broadcast Ciphertext-Policy Attribute-Based Encryption （BCP-ABE） and an attribute hierarchy into CBE. The experiment results show that the FGUR scheme has better performance in terms of the encryption cost and dynamic access privilege, compared with CBE.