2012 Fiscal Year Final Research Report

A study on construction of computationally independent one-way functions and their application to cryptographic protocol

Research Project

Project/Area Number	23650008
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Fundamental theory of informatics
Research Institution	Kyushu University
Principal Investigator	SAKURAI Kouichi 九州大学, システム情報科学研究院, 教授 (60264066)
Project Period (FY)	2011 – 2012
Keywords	暗号理論 / 一方向性関数 / 疑似乱数生成 / 計算理論 / Diffie-Hellmann 問題 / 暗号プロトコル / 堅固性 / 安全性評価
Research Abstract	We succeed to construct an explicit pair ofcomputationally independent one-way functions from the hardness of the discrete logarithm problem. Our proof argument is based on the square Deffie-Hellmann problem. This main result is presented in Symposium of Cryptography and Information Security 2013 . Also we get a joint researcher, Prof. Yunlei ZHAO (Fudan Univ. China) who was visiting in Singapore Management Univ. when Kouichi SAKURAI has visited the security lab. His suggestion issome relationship between non-malleability of functions and our notion of computationally independent one-way functions. Prof. Yunlei ZHAO has visited Kyushu Univ. from Sept 2012 for 6 months thanks to NICT’s inviting program of foreign researcher to Japan, and we perform joint research on this topic including cryptographic key exchange protocols, a partial result of which is presented also in Symposium of Cryptography and Information Security 2013.