从属性基加密到功能加密的扩展安全模型与新方法研究

The evolution from attribute based encryptions to functional encryptions is a theoretical extension of great importance in the cryptology field, all of which are advanced cryptographic primitives derived from identity based encryption during recent several years. Just after many research results were proposed by a lot of famous scholars, the cryptology community has established a series of effective methods and techniques for constructing some special form of functional encryptions, such as identity based encryption and functional encryption for boolean formula. However there still exist many important theoretical issues on functional encryptions, including basic identity based encryptions, concrete attributed based encryptions and even more general form, which are required to be studied and resolved. Our project mainly focuses on the extended security model and construction method of functional encryptions, and hopes to narrow the gap between the theoretical research and its practical applications by investigating security model closer to real scenario and developing new methods for constructing various types of functional encryptions. For the aspect of extended security model, our project involves user revocation, traceability after key leakage and security under the selective opening attack. For the development of new construction methods, our project will start from the dual system technique, which evolved swiftly during recent years, and reaches the goal of improving the performance via developing new idea for realizing dual system strategy. Apart from those, the project also concerns about the cost of introducing revocation and traceability mechanism into the system. it is also our goal to gain better security guarantee with less cost in terms of system performance. Therefore our project has very important theoretical value, as well as a very broad application of practice.

从属性基加密到功能加密是密码学中又一个理论扩展，是近年来在身份基加密之上发展而来的高级密码学原语。经过一大批著名学者的研究，目前已经找到了一些有效的方法和技术去构造某些特殊的功能加密系统。但是，无论是属性基加密，还是功能加密，其中都还有一些重要的理论问题有待研究并解决。本项目将从属性基加密和功能加密的扩展安全模型和构造方法入手，以期通过研究更加接近现实应用场景的安全模型和发展有关的构造方法拉近理论和实际的距离。在扩展安全模型方面，将主要致力于解决功能加密的可追踪性、可撤销性以及在选择打开攻击下的安全性问题；在发展新方法方面，将以近期快速发展的双系统证明技术为基础，通过探索双系统证明技术的高效实现来改善功能加密的性能。此外，本项目还将关注可追踪性、可撤销性等引入对系统性能的影响，以更少的代价获得更佳的安全保障是本项目的又一个追求。因此，本项目的研究既有重要的理论价值，也有非常广阔的应用前景。

本项目系统地研究了从属性基加密到功能加密的扩展安全模型与新方法的相关课题，取得了一系列重要突破，发表62篇学术论文，其中有11篇属于CCF A类或JCR一区论文，包括CRYPTO、ACM CCS上发表3篇论文，14篇属于JCR二区期刊/CCF B类论文，包括IEEE Transactions on Services Computing、Des. Codes Cryptography、ASIACRYPT、ICDCS等，SCI检索26篇，EI检索62篇。项目负责人和主要研究人员还应邀在国内外学术会议以及在高校做邀请报告10余次，获得软件著作权10项。.本项目主要创新性工作包括：.（1）解决了功能加密安全模型的扩展性难题，在标准假设下获得紧规约身份基加密高效的构造，提出了两种扩展安全模型：追踪存储代价为零的白盒可追踪和可追责可撤销白盒可追踪，基于DRSA假设构造了All-but-many有损陷门函数，在新假设下推广Goldwasser-Micali密码系统，提出了匿名IBE方案及推广的Galbraith测试。.（2）提出了具有σ次细粒度访问控制机制的可审计密文策略属性基加密方案，提出了基于任意属性基加密/功能加密的轻量隐私保护方案和支持关键字快速搜索的基于密文策略的属性基加密方案，扫清了云计算中实现密文访问控制的障碍。.（3）密码学基础问题上取得重大成果，包括给出国际标准哈希函数RIPEMD-160的最好分析结果，构造了一个能自动规避矛盾的差分特征搜索模型，对基于Gimli的哈希方案和认证加密方案进行了安全性分析，证明了只使用一个轮函数的3轮KAC（3KACSP）结构是3n/4比特安全的。.（4）提出了在保护用户隐私的前提下高效的实现对加密网络流的深度检测方法，基于多输入的內积加密提出了安全高效的多关键词可搜索加密方案和不基于公钥全同态加密的图像特征提取和图像匹配隐私保护方法。.（5）发现了一系列轻量化隐私计算方法。.此外，本项目还扩展了许多研究。受资助期间，项目负责人和项目组成员获得了教育部自然科学一等奖，一篇论文获得国际高水平期刊《The Computer Journal》2019年Wilkes奖，还培养毕业5名博士、18名硕士以及1名博士后出站。