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密码讲堂 | 20220613王浩洋博士

  • 文/密码学院
  • 日期：2022-06-12
  • 3215
Key Structures: Improved Related-Key Boomerang Attack against the Full AES-256
报告人：王浩洋 博士（上海交通大学）
会议时间: 2022-06-16 14:00-16:00
腾讯会议: 812-156-475
报告摘要：
This paper introduces structure to key, in the related-key attack settings. While the idea of structure has been long used in keyrecovery attacks against block ciphers to enjoy the birthday effect, the same had not been applied to key materials due to the fact that key structure results in uncontrolled differences in key and hence affects the validity or probabilities of the differential trails. We apply this simple idea to improve the related-key boomerang attack against AES-256 by Biryukov and Khovratovich in 2009. Surprisingly, it turns out to be effective, i.e., both data and time complexities are reduced by a factor of about 2^8, to 2^92 and 2^91 respectively, at the cost of the amount of required keys increased from 4 to 2^19. There exist some tradeoffs between the data/time complexity and the number of keys. To the best of our knowledge, this is the first essential improvement of the attack against the full AES-256 since 2009. It will be interesting to see if the structure technique can be applied to other AES-like block ciphers, and to tweaks rather than keys of tweakable block ciphers so the amount of required keys of the attack will not be affected.
报告人简介：
王浩洋，2016年毕业于山东大学数学学院，获理学学士学位。2021年毕业于新加坡南洋理工大学，获密码学博士学位，博士毕业论文获得新加坡数学协会优秀博士论文奖章。2021年4月加入上海交通大学网络空间安全学院，现任职助理教授。主要研究方向为分组密码算法以及哈希函数的分析与设计。