みなさま，

こんにちは！ 東京大学の蓮尾と申します． 急なご案内ですが，講演を2件，お知らせさせてください．

木曜日のご講演は暗号理論の専門家によるものですが，内容は 暗号プロトコルの形式検証（計算論的安全性）に動機づけられた ものです．形式検証の人向けに話してもらえるよう，お願いしてあります．

金曜日は線形論理・ゲーム意味論の専門家によるご講演です． NII でも明日お話されるようですので，ぜひあわせてどうぞ．

会場のアクセスは， http://www-mmm.is.s.u-tokyo.ac.jp/index.html をご覧下さい．

みなさまのお越しをお待ちしております．それでは！

蓮尾 一郎 東京大学 コンピュータ科学専攻 http://www-mmm.is.s.u-tokyo.ac.jp

Thu 12 Apr 2012, 16:40-18:10 David Galindo http://www.dgalindo.es/ (U. Luxembourg), Encryption Schemes Secure in the Presence of Key Cycles 理学部7号館5階 511教室 Room 511, School of Science Bldg. No. 7

Traditionally the security of encryption schemes has relied on the assumption that the decryption keys are not accessible to the attacker neither directly (e.g. some parts of the decryption key might have been leaked) nor indirectly (e.g. never encrypt messages that depend on the decryption key). However this assumption has been challenged in different contexts in the last decade. The main sources have been side-channel attacks and formal cryptography.

In this talk we will give an introduction to the traditional security notions for encryption schemes as well as the new notion of security in the presence of key cycles. We will explain why the latter notion is difficult to achieve using previous techniques. Finally we will introduce the first practical encryption scheme achieving the latter security notion (appeared at CRYPTO 2008).

Fri 13 Apr 2012, 16:40-18:10 Paul-Andre Mellies http://www.pps.jussieu.fr/%7Emellies/ (U. Paris VII), Tensorial logic: a type-theoretic foundation for game semantics 理学部7号館1階 102教室 Room 102, School of Science Bldg. No. 7

Tensorial logic is a primitive logic of tensor and negation which refines linear logic by relaxing the hypothesis that negation is involutive. I will explain how the logic provides a type-theoretic foundation to game semantics, and how it may be extended with algebraic effects in order to recover specific categories of games and strategies.