KYUDAI NEWS KYUSHU UNIVERSITY CAMPUS MAGAZINE Spring 2013 No.24

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Professor Tsuyoshi Takagi, Institute of Mathematics for Industry, Kyushu University broke a world cryptography record with the successful cryptanalysis of a 278-digit (923-bit) - long pairing-based cryptography,*1 which is now becoming the next generation cryptography standard. This research was jointly from The National Institute of Information and Communications Technology (NICT), Fujitsu Laboratories Limited and Kyushu University.Until now, cryptanalysis of pairing-based cryptography of this length was thought impossible as it was estimated to take several hundred thousand years to break. Indeed, despite numerous efforts to use and spread this cryptography at the development stage, it wasn’t until this new way of approaching the problem was applied that it was proven that pairing-based cryptography of this length was fragile and could actually be broken in 148.2 days. This result is used as the basis of selecting secure encryption technology, and is proving useful in the standardization of next-generation cryptography in electronic government systems in Japan and international standardization organizations.BackgroundMany cryptography systems are used from the viewpoint of information security on a modern information system. Recently, much attention has been paid to the new “pairing-based” cryptography system, which is being standardized as a next-generation encryption system. The technology is attractive as it can be used for various useful applications such as “Identity-based encryption*2”, “keyword searchable encryption*3”, and “functional encryption*4”, which were impossible using previous public key cryptography*5.Technological IssuesAs cryptanalytic techniques and computers become more advanced, cryptanalytic speed accelerates, and conversely, cryptographic security decreases. Therefore, it is important to evaluate how long the cryptographic technology can be securely used. On the other hand, pairing-based cryptography has not advanced, so it was premature to evaluate its security against a new attack method.Highlight of Recent ResearchProfessor Tsuyoshi TakagiThe division of Advanced Mathematics Technology, Institute of Mathematics for IndustryKyudai News No.2411Kyushu University, Achieve World Next-Generation Establishing security for pairing-based cryptography and contributing to its standardization as the next-generation cryptography.

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