密文长度恒定且属性直接可撤销的基于属性的加密  

Attribute Directly-revocable Attribute-based Encryption with Constant Ciphertext Length

作　　者：张应辉[1,2] 郑东[1] 李进[3] 李晖[4] 

机构地区：[1]西安邮电大学无线网络安全技术国家工程实验室,西安710121 [2]中国科学院信息工程研究所信息安全国家重点实验室,北京100093 [3]广州大学计算机科学与教育软件学院,广州510006 [4]西安电子科技大学综合业务网理论及关键技术国家重点实验室,西安710071

出　　处：《密码学报》2014年第5期465-480,共16页Journal of Cryptologic Research

基　　金：国家自然科学基金项目(61402366;61272457;61272037;61472472;61472091);陕西省自然科学基础研究计划重点项目(2013JZ020);工信部重大专项(2013ZX03002004)

摘　　要：密文策略的基于属性的加密(Ciphertext-Policy Attribute-Based Encryption:CP-ABE)特别适合于云计算环境下的访问控制系统.在大部分已有的CP-ABE方案中,密文长度会随着访问策略的复杂性的增加而线性增大,且属性撤销问题没有得到解决.属性撤销机制是CP-ABE在实际应用中的一个基本要求,与间接的属性撤销机制相比,直接的属性撤销机制效率更高,不存在由密钥更新所带来的性能瓶颈.在已有的大部分支持属性撤销的CP-ABE方案中,每次撤销事件的发生都要求对所有的密文进行更新.提出了密文长度恒定且属性直接可撤销的CP-ABE方案.在随机预言机模型中,基于判定性m-BDHE假设,证明了新方案的安全性,这里m表示系统中用户总数的一个上界.在新方案中,通过引入适用于多属性值环境的撤销辅助判断函数,判断当属性撤销事件发生时,是否需要对一个密文进行更新.所提出的方案支持具有多个属性值和通配符的AND策略.性能分析和比较表明新方案适用于实际应用,特别是用户属性变化频繁且带宽资源受限的场景.Ciphertext-policy attribute-based encryption(CP-ABE) is very suitable for realizing access control systems in cloud computing. In most of existing CP-ABE schemes, the ciphertext length linearly increases with the complexity of access policies and the attribute revocation issue remains to be an unsolved problem. Attribute revocation mechanisms are indispensable for practical adoption of CP-ABE. Compared with indirect attribute revocation, direct revocation enjoys better efficiency because it removes the performance bottleneck due to secret key update. In most of existing attribute revocable CP-ABE schemes, all the ciphertexts have to be updated whenever a revocation event occurs. In this paper, we propose an attribute direct-revocable CP-ABE scheme with constant ciphertext length. The proposed scheme is proven to be secure in the random oracle model under the decision m-BDHE assumption, where m is an upper bound of the number of users in the system. In the proposed scheme, an auxiliary revocation judgment function is introduced to check whether a ciphertext should be updated or not when revocation events occur. The proposed scheme can support AND-gate access policies with multiple attribute values and wildcards. Performance analysis and comparisons indicate that the proposed CP-ABE scheme is extremely suitable for real-world applications, especially for the scenarios where users' attributes change frequently and bandwidth issues are major concerns.

关 键 词：云计算 恒定的密文长度 直接的属性撤销 基于属性的加密 

分 类 号：TP309.7[自动化与计算机技术—计算机系统结构]