讲座题目： SMS4算法和类SMS4算法的安全性分析

讲座人：   李超 教授

讲座时间： 14:30—16:00

讲座日期： 2017-6-22

地点：   长安校区文津楼三段6层622报告厅  

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讲座内容简介：

SMS4算法是中国无线局域网推荐使用的分组密码算法，它采用4分支非平衡Feistel结构，分组长度和密钥长度均为128位，迭代轮数32轮，轮函数为SP型。本报告给出了SMS4算法12轮不可能差分区分器与零线性相关区分器存在的一个充分条件，该条件与S盒选取无关，并指明了ICICS2007上吕继强得到的12轮不可能差分区分器和CRYPT2005上孙兵得到的12轮零相关线性区分器与S盒无关。证明了当Feistel结构的分支数n为偶数，轮函数为SP型时，类SMS4算法和类MARS算法均存在3n轮的不可能差分区分器与零线性相关区分器，并且这些区分器分S盒选取无关。

讲座人简介

李超，国防科技大学教授、博士生导师，中国密码学会理事、湖南省数学会常务理事。主持重点研发计划课题、863课题和国家自然科学基金课题等20余项科研项目；在科学出版社和高等教育出版社等出版专著2部、教材6部、会议录3部；在 IEEE Trans. on  Information Theory 和 Science In China 等学术刊物上发表100余篇研究论文，其中SCI论文50余篇，EI论文60余篇。先后获得军队科技进步一等奖1项，部委级科技进步二等奖2项，军队院校育才奖金奖和银奖各一次。

Abstract: The SMS4 block cipher is recommended by the Chinese government as their part WAPI standard for wireless networks. SMS4 adopts a 4-branch unbalanced Feistel structure and with a 32-round iterations of SP-type round function. The block size and key size are both 128 bits. This report presents a necessary and sufficient condition for the existence of 12-round impossible differential distinguisher and 12-round zero correlation linear distinguisher, which is independent of the choices of the S-boxes. We also point out that both the 12-round impossible differential distinguisher given by Jiqiang Lv in ICICS 2007 and the 12-round zero correlation linear distinguisher given by Bing Sun in CRYPTO 2015 are independent of the S-boxes. Furthermore, we proved that when the branch number of the Feistel structure n is even and round function is SP-type, both SMS-like cipher and MARS-like cipher exist 3n-round impossible differential distinguisher and 3n-round zero correlation linear distinguisher, which are independent of the choices of the S-boxes.

Biography: Chao Li, Professor, Doctoral Supervisor, National University of Defense Technology. Director of Chinese Association for Cryptologic Research(CACR). Managing Director of Mathematical Association of Hunan Province. Leader of more than 20 researching projects, including Key Research and Develop Plan, 863 Project, National Natural Science Foundation of China and so on. His works have been published by Science Press and Higher Education Press etc., including 2 monographs, 6 text books and 3 conference proceedings. He has published more than 100 research papers on journals such as IEEE Trans. on Information Theory and Science in China, of which more than 50 papers are indexed by SCI, and more than 60 papers are indexed by EI. He also got a First prize in military scientific and technological progress, a Second prize in ministerial level scientific and technological progress, as well as Military academy YuCai prize gold award and silver award.