Classical/Quantum Security Analyses of Symmetric Key Cryptosystems

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K11675
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 60010:Theory of informatics-related
• Research Institution: Nagoya University
• Principal Investigator: Iwata Tetsu 名古屋大学, 工学研究科, 教授 (90344837)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 共通鍵暗号 / 安全性解析 / 古典的攻撃 / 量子攻撃

Outline of Final Research Achievements

This research aims to develop symmetric key cryptosystems suitable for use in the quantum era. Towards this goal, we study the security of main techniques of symmetric-key cryptosystems in terms of both classical and quantum attacks. As our main results, we analyzed the security of generalized Feistel ciphers, where a tweakable block cipher is used as a component, in a classical setting. We clarified the relationship between the number of rounds and the security, and we also clarified the trade-off between the length of the secret key and the security. In the quantum setting, we analyzed the security of the Sum of Even-Mansour pseudorandom function and the disk sector encryption called Adiantum.

Free Research Field

情報学基礎論関連

Academic Significance and Societal Importance of the Research Achievements

古典的攻撃に対し高い安全性と計算効率を兼ね備えた共通鍵暗号技術の設計は重要な研究課題であり、本研究のブロック暗号の構成に関する成果は、この課題に対する一定の解を与えている。また、量子コンピュータが実現された際の共通鍵暗号技術の安全性への影響は解明しきれていない、という課題があった。本研究の量子安全性、量子攻撃に関する成果は、この課題に対する一定の解を与えている。