Research on Lightweight Stream cipher

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K12698
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Information security
• Research Institution: University of Hyogo
• Principal Investigator: Isobe Takanori 兵庫県立大学, 応用情報科学研究科, 准教授 (30785465)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: 共通鍵暗号 / ストリーム暗号 / 軽量暗号 / 暗号解析

Outline of Final Research Achievements

In this research project, we proposed new security evaluation methods for lightweight stream ciphers. Specifically, we focused on some structural properties of lightweight stream ciphers, and then developed new attacks exploiting structures of stream ciphers such as impossible collision attacks, cube attacks based on non-blackbox analysis. These enable more accurate security evaluations of known stream ciphers, and finding some insights to design new primitives and components for lightweight stream ciphers. As a result, we succeeded in designing new three lightweight stream ciphers called LILLE, TRIVIUM^2, and Triad. LILLE is based on an Even-Mansour structure, and achieves low area while keeping a strong security property. TRIVIUM^2 is a variant of well-known stream cipher Trivium, and enables low energy implementation but requires more area than LILLE. Triad achieves lightweight implementation, low energy, and high security. These are expected to be used for IoT devices.

Free Research Field

暗号技術

Academic Significance and Societal Importance of the Research Achievements

本研究では，未解決問題であった様々な新しい軽量ストリーム暗号の安全性評価手法を開発することに成功した．これにより，構造毎の正確な安全性評価ができ，安全でかつ効率的な構造の設計が可能になった．実際，新しい設計方法に基づく軽量ストリーム暗号アルゴリズムを複数開発した．これは，学術レベルでは軽量ストリーム暗号の理論の発展に寄与し，また産業レベルでは，今後世の中で求められる様々な実装や安全性要求に適応可能な軽量なストリーム暗号の効果的な開発につながる．具体的には，RFIDやセンサー等のリソースの乏しいデバイスに対しても実装可能なストリーム暗号の開発等につながり，その波及効果は非常に大きい．