Transposition of AES Key Schedule

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• 关键词：AES ; Key schedule ; Meet ; in ; the ; middle ; Related ; key ; Differentials ; MixColumns
• 刊名：Lecture Notes in Computer Science
• 出版年：2017
• 出版时间：2017
• 年：2017
• 卷：10143
• 期：1
• 页码：84-102
• 丛书名：Information Security and Cryptology
• ISBN：978-3-319-54705-3
• 卷排序：10143

文摘

In this paper, we target the poor diffusion pattern in the key schedule of AES. More specifically, the column-by-column word-wise property in the key schedule matches closely with the MixColumns operation in the round diffusion, which leads to several attacks in both single-key and related-key model. Therefore, we propose a new key schedule by switching the interaction from between different columns to between different rows, which offers stronger security than the original AES key schedule and better efficiency than other key schedule proposals. First, our proposal reduces the number of rounds of several single-key attacks, such as popular SQUARE attacks and meet-in-the-middle attacks, e.g. Derbez et al., EUROCYRPT 2013 and Li et al., FSE 2014. Meanwhile, it increases the security margin for AES in the related-key model, namely making the related-key differential attacks with local collisions which broke the full rounds of AES impossible.