Achievement Award  




@Modern information systems have numerous applications that require use of confidential information; for example, Internet shopping, Internet banking, and electronic submissions to public agencies. In addition, protection of privacy data and corporate secret data coexisting with useforprofit is becoming a problem with the spreading use of various services that utilize cloud systems through such vehicles as smart phones and tablet PCs. The nextgeneration cryptography gpairingbased cryptography,h which has wide application, is attracting attention as one of the best solutions to this problem. Pairingbased cryptography is a type of public key cryptosystem that uses bilinear mapping, which is called a pairing on an elliptic curve. It can make possible a number of novel and flexible services, such as gsearchable encryptionh, gfunctional encryptionh and gIDbased encryptionh, which could not be provided through conventional publickey cryptography. This encryption technology is expected to offer new services and improved convenience and security of cloud type information. However, pairingbased cryptography does not have a long history in cryptography, and its security has not yet been deeply studied. @The winners concentrated their respective specialized skills in cryptology, cryptographic skill, number theory, and computer programming to achieve a cryptanalysis world record pairingbased cryptosystem of 278 digits (923 bits), which had been thought to be impossible as it was estimated that the attack would take several hundred thousand years to break. Concurrently, they succeeded in accurately estimating the calculation resource and time necessary for the cryptanalysis. (Figure 1) @In their experiment of breaking the pairingbased cryptography, they used the gfunction field sieve,h which is currently the fastest algorithm for solving the discrete logarithm problem over the characteristic 3 which is related to security of the cryptosystem. The function field sieve method comprises four processes: the polynomial selection part, the relation search part, the linear algebra part, and the individual discrete logarithm part. It is known that a number of computational complexities are especially needed for the relation search part and processing of the linear algebra part. @There were two main points to their success in the cryptanalysis. First, they extended the previous method gline sieveh for the data search to the twodimensional space called glattice sieveh and they developed an algorithm that reduced the range of each degree in the searched polynomial space. Second, they proposed several mathematical formulas with which they could estimate in advance the required computational powers for their experiment of the relation search part and the linear algebra part, and then they selected the initial parameter of the smallest computational power from the theoretically possible options. (Figure. 2)
@As mentioned above, they have been acknowledged as having promoted the spread of nextgeneration cryptography, and to have led this outstanding achievement of a technology that has contributed to secure utilization of cloud computing. Their work has been recognized with the IPSJ Kiyasu Special Industrial Achievement Award 2012 and the 12th Docomo Mobile Science Award (Advanced Institute for Materials Research). Their distinguished achievements are highly notable and deserving of this achievement award. 

References  
(P)@Takuya Hayashi, Takeshi Shimoyama, Naoyuki Shinohara, Tsuyoshi Takagi, gBreaking Pairing Based Cryptosystems Using ÅT Pairing over GF(3O97)h, ASIACRYPT 2012, Springer LNCS 7658, pp.4360, 2012. (Q)@Naoyuki Shinohara, Takeshi Shimoyama, Takuya Hayashi, Tsuyoshi Takagi, gKey Length Estimation of Pairingbased Cryptosystems Using ÅT Pairing Over GF(3On)h, IEICE Transactions, Vol.E97A, No.1, pp.236244, 2014. (R)@Takuya Hayashi, Naoyuki Shinohara, Lihua Wang, Shin'ichiro Matsuo, Masaaki Shirase, Tsuyoshi Takagi, gSolving a 676bit Discrete Logarithm Problem in GF(3O(6n))h, Transactions Vol.E95A, No.1, pp.204212, 2012. (S)@Tadashi Iyama, Shinsaku Kiyomoto, Kazuhide Fukushima, Toshiaki Tanaka, Tsuyoshi Takagi, gImplementation of Pairing Based Cryptosystem on Mobile Phonesh, IEICE Transactions, Vol. J95A, No.7, pp.579587, 2012. (T)@JeanLuc Beuchat, Hiroshi Doi, Kaoru Fujita, Atsuo Inomata, Piseth Ith, Akira Kanaoka, Masayoshi Katouno, Masahiro Mambo, Eiji Okamoto, Takeshi Okamoto, Takaaki Shiga, Masaaki Shirase, Ryuji Soga, Tsuyoshi Takagi, Ananda Vithanage, Hiroyasu Yamamoto, gFPGA and ASIC Implementations of theÅT Pairing in Characteristic Threeh Computers & Electrical Engineering, Vol.36, No.1, pp.7387, 2010. (U)@Takuya Hayashi, Masaaki Shirase, Tsuyoshi Takagi, gAn Experiment on Implementation of the Function Field Sieve over GF(3On)h, IPSJ Journal, Vol.50, No.9, pp.19561967, 2009. (V)@JeanLuc Beuchat, Nicolas Brisebarre, Jérémie Detrey, Eiji Okamoto, Masaaki Shirase, Tsuyoshi Takagi, gAlgorithms and Arithmetic Operators for Computing the ÅT Pairing in Characteristic Threeh, IEEE Transactions on Computers, Vol.57, No.11, pp.14541468, 2008. 
