流密码可约性高效判别算法存在性的研究

项目名称： 流密码可约性高效判别算法存在性的研究

项目编号： No.61502441

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 自动化技术、计算机技术

项目作者： 王林

作者单位： 中国电子科技集团公司第三十研究所

项目金额： 21万元

中文摘要： 流密码在信息保密和认证领域有广泛的应用前景，可约性是影响流密码安全强度的一个重要指标，研究是否存在高效率的一般性准则或方法判定流密码算法的可约性具有重要的理论意义。通过重点考察是否存在高效率的方法以判定非线性移位寄存器的可约性，从图论、有限状态机、代数几何等多角度建立流密码算法的抽象模型，发掘模型中体现的整体和局部关系，利用模型刻画颗粒的模糊度变化，探索流密码算法可约性的高效一般性判别算法的存在性，为有效判定流密码算法是否退化提供理论依据，对流密码算法退化性问题的难度给出理论证据。设计流密码算法的迭代表达方式搜索算法，针对若干类流密码模式，提出判断其可约性的可计算的指标或高效率的算法，为流密码算法的设计和分析提供技术支撑。

中文关键词： 设计准则；退化性；可约性；可计算性；非线性反馈移位寄存器

英文摘要： Stream ciphers are prospectively employed for confidentiality and authentication in a broad expansion of information technology, and reducibility is a substantial index to measure security of stream ciphers. It is therefore of significant theoretical interests to study whether there exists an efficiently computable criterion or algorithm to determine reducibility of stream ciphers. First, whether there exists an efficient algorithm to decide reducibility of nonlinear feedback shift registers is studied. Furthermore, abstract models of stream ciphers are configured respectively from the perspective of graphs, finite state automata and algebraic geometry. Finally, through the relation of local parts and global ciphers and via obscuration of those models, it is expected to answer existence of efficient algorithms for reducibility of stream ciphers. The achievements serve as theoretical base of, and also as witness to difficulty of, testing degeneracy of stream ciphers. Additionally, algorithms are devised to search recurrent expressions of stream ciphers, and thereby reducibility of stream ciphers with certain particular structures is tested algorithmically, which adds technical ingredients in design and analysis of stream ciphers.

英文关键词： design criteria;degeneracy;reducibility;computability;nonlinear feedback shift register