




Invited Talk 1
Damien Stehlé,
Ecole Nromale Supérieure de Lyon,
"Making NTRUEncrypt and NTRUSign as Secure as WorstCase Problems over Ideal Lattices"
Abstract. Â NTRUEncrypt, proposed in 1996 by Hoffstein, Pipher and Silverman, is the fastest known latticebased encryption scheme. Its moderate keysizes, excellent asymptotic performance and conjectured resistance to quantum computers make it a desirable alternative to factorization and discretelog based encryption schemes. However, since its introduction, doubts have regularly arisen on its security. In this talk, I will describe a modification of NTRUEncrypt that is semantically secure (INDCPA). The security holds under the assumption that quantum computers cannot efficiently solve some standard worstcase problems on euclidean lattices, when they are restricted to a family of lattices related to cyclotomic number fields. The main component of the security proof is to show that if the secret key polynomials are selected from discrete Gaussians, then the public key, which is their ratio in a polynomial ring over a prime field, is statistically close to uniform over its range. I will also describe the first key generation algorithm for NTRUSign that provably runs in polynomial time. Combined with the above results on the NTRUEncrypt key generation algorithm, this leads to a variant of NTRUSign that is provably unforgeable (in the random oracle model). The security of the modified NTRUEncrypt and NTRUSign schemes then follows from the already proven hardness of the RingSIS and RingLWE problems.
Affiliation and short biography. Â Damien Stehlé is professor at the Ecole Normale SupÃ©rieure de Lyon, France. He received his Ph.D. Degree in computer science from the UniversitÃ© Nancy 1, France, in 2005, and his Habilitation from ENS de Lyon in 2011. His research interests include cryptography, algorithmic number theory, computer algebra and computer arithmetic, with emphasis on the computational aspects of Euclidean lattices.
Invited Talk 2
Jeong Woon Choi,
Quantum Tech. Lab in SK telecom, developing a signal processing board for QKD system,
"Introduction to Quantum Cryptography and its Technology Trends"
Abstract. According to the advance of semiconductor fabrication technology, the speed of processors has been evolving exponentially faster. This is making a great contribution to the growth of market area and the performance of security technology. However, it has also, ironically, facilitated various hacking techniques and increased security breaches. Especially, in 1994, it was theoretically proved that quantum computer could break any public cryptosystems based on integer factoring or discrete logarithm. Quantum cryptography provides an unconditional security with no limit on the computing power of adversaries, by using the fundamental principles of quantum mechanics such as uncertainty and noclonability. The most representative area of quantum cryptography is the quantum key distribution (QKD) and in fact several foreign companies are on selling their products already. In this talk, I will introduce the concepts and importance of quantum cryptography and its global technology trends.
Affiliation and short biography. Jeong Woon Choi is research associate at Quantum Tech. Lab in SK telecom, Korea. He received his Ph.D. Degree in Department of Mathematical Science, Seoul National University, Korea, in 2006, and majored in quantum information and computation. He worked at Cryptography Research Team, Electronics and Telecommunications Research Institute from 2008 to 2011. His research interests include developing a signal processing board for QKD system.



