Security Analysis of Post-Quantum Cryptography

2020 Fiscal Year Final Research Report

• Project/Area Number: 17K00185
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Information security
• Research Institution: The University of Tokyo
• Principal Investigator: Tsuyoshi Takagi 東京大学, 大学院情報理工学系研究科, 教授 (60404802)
• Co-Investigator(Kenkyū-buntansha): 安田 雅哉 立教大学, 理学部, 准教授 (30536313)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 暗号・認証等 / 公開鍵暗号 / ポスト量子暗号 / 格子暗号

Outline of Final Research Achievements

In this research project, we conducted research on the derivation of secure cryptographic parameters for the standardization of post-quantum cryptography (PQC). In particular, we evaluated the difficulty of the Learning with Errors (LWE) problem, which is the basis of the security of lattice-based cryptography, and we achieved a world record for solving the 70-dimensional LWE problem in 32.7 CPU hours in the LWE challenge hosted by Darmstadt University of Technology. We also constructed an efficient key exchange scheme based on the difficulty of the ring-LWE problem and proposed cryptographic parameters to achieve the security level of the NIST PQC standardization project. Furthermore, the security of various attack methods against lattice-based cryptography (modulus switching attack, key reuse attack, etc.) was evaluated.

Free Research Field

暗号理論

Academic Significance and Societal Importance of the Research Achievements

本研究課題では、格子暗号に対して堅牢な計算量評価と実計算環境による大規模解読実験を行い、攻撃法の現実的なfeasibilityを評価することにより、128ビット安全性を有する具体的な暗号パラメータの導出を行った。本研究課題により、ポスト量子暗号の安全性検証法を深化させ、その安全な暗号パラメータの選定に貢献できるため学術的かつ実用的な波及効果は大きい。