# Atsushi Takayasu

I am an assistant professor in the University of Tokyo, Graduate School of Information Science and Technology, Department of Mathematical Informatics.

I am a member of Mathematical Informatics 1st Laboratory.

My research interest is cryptography, especially lattices, lattice reductions, and cryptanalysis.

See dblp, google scholar citations.

Mathematical Informatics 1st Laboratory, Faculty of Engineering Bldg. #6, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, JAPAN

e-mail: takayasu[at]mist.i.u-tokyo.ac.jp

tel: +81-3-5841-6914

- Bachelor of Engineering from Mathematical Engineering Course, Department of Mathematical Engineering and Information Physics, Faculty of Engineering, The University of Tokyo, March 2012.
- Master of Science from Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, March 2014. (Supervisor, Noboru Kunihiro)
- JSPS Research Fellowship for Young Scientists (DC1), April 2014 - March 2017.
- Collaborative Researcher in National Institute of Advanced Industrial Science and Technology (AIST), April 2015 - Now.
- Ph.D of Science from Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, March 2017. (Supervisor, Noboru Kunihiro)
- Assistant professor in the University of Tokyo, Graduate School of Information Science and Technology, Department of Mathematical Informatics, April 2017 - Now.

## Refereed International Journal

Refereed International Journal

- A. Takayasu and N. Kunihiro. Partial Key Exposure Attacks on RSA: Achieving the Boneh-Durfee Bound. Theoretical Computer Science.
- A. Takayasu, Y. Lu, and L. Peng. Small CRT-exponent RSA Revisited. Journal of Cryptology, 2018.
- A. Takayasu and N. Kunihiro. General Bounds for Small Inverse Problems and Its Applications to Multi-Prime RSA. IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E100-A, No. 1, pp. 50-61, 2017.
- A. Takayasu and N. Kunihiro. Better Lattice Constructions for Solving Multivariate Linear Equations Modulo Unknown Divisors. IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E97-A, No. 6, pp. 1259-1272, 2014.

## Refereed International Conference Proceeding

Refereed International Conference Proceeding

- H. Okada, A. Takayasu, K. Fukushima, S. Kiyomoto, and T. Takagi. On the complexity of the LWR-Solving BKW Algorithm. ICISC 2018.
- W. Wang, Y. Wang, A. Takayasu, and T. Takagi. Estimated Cost for Solving Generalized Learning with Errors Problem via Embedding Techniques. Proc. IWSEC 2018, Springer, 2018. (presented by the first author, the first author received
**Best Student Paper Award**) - A. Takayasu and Y. Watanabe. Lattice-based Revocable Identity-based Encryption with Bounded Decryption Key Exposure Resistance. Proc. ACISP 2017, LNCS 10342, pp. 184-204, Springer, 2017. [ePrint]
- A. Takayasu, Y. Lu, and L. Peng. Small CRT-exponent RSA Revisited. Proc. Eurocrypt 2017, LNCS 10211, pp. 130-159, Springer, 2017. [ePrint]
- A. Takayasu and N. Kunihiro. A Tool Kit for Partial Key Exposure Attacks on RSA. Proc. CT-RSA 2017, LNCS 10159, pp. 58-73, Springer, 2017. [ePrint]
- A. Takayasu and N. Kunihiro. Small Secret Exponent Attacks on RSA with Unbalanced Prime Factors. Proc. ISITA 2016, pp. 236-240, IEEE, 2016.
- A. Takayasu and N. Kunihiro. Partial Key Exposure Attacks on CRT-RSA: General Improvement for the Exposed Least Significant Bits. Proc. ISC 2016, LNCS 9866, pp. 35-47, Springer, 2016.
- A. Takayasu and N. Kunihiro. Partial Key Exposure Attacks on RSA with Multiple Exponent Pairs. Proc. ACISP 2016, LNCS 9723, pp. 243-257, Springer, 2016. (
**Best Student Paper Award**) - A. Takayasu and N. Kunihiro. How to Generalize RSA Cryptanalyses. Proc. PKC 2016, LNCS 9615, pp. 67-97, Springer 2016. [ePrint]
- K. Takashima and A. Takayasu. Tighter Security for Efficient Lattice Cryptography via the Renyi Divergence of Optimized Orders. Proc. ProvSec 2015, LNCS 9451, pp. 412-431, Springer, 2015. [ePrint]
- A. Takayasu and N. Kunihiro. Partial Key Exposure Attacks on CRT-RSA: Better Cryptanalysis to Full Size Encryption Exponents. Proc. ACNS 2015, LNCS 9092, pp. 518-537, Springer, 2015.
- A. Takayasu and N. Kunihiro. General Bounds for Small Inverse Problems and Its Applications to Multi-Prime RSA. Proc. ICISC 2014, LNCS 8949, pp. 3-17, Springer, 2014. [ePrint]
- A. Takayasu and N. Kunihiro. Partial Key Exposure Attacks on RSA: Achieving the Boneh-Durfee Bound. Proc. SAC 2014, LNCS 8781, pp. 345-362, Springer, 2014. [ePrint]
- A. Takayasu and N. Kunihiro. Cryptanalysis of RSA with Multiple Small Secret Exponents. Proc. ACISP 2014, LNCS 8544, pp. 176-191, Springer 2014.
- A. Takayasu and N. Kunihiro. Better Lattice Constructions for Solving Multivariate Linear Equations Modulo Unknown Divisors. Proc. ACISP 2013, LNCS 7959, pp. 118-135, Springer, 2013.

## Other International Conference Talks

Other International Conference Talks

- K. Matsuda, A. Takayasu, and T. Takagi. Explicit Relation between Low-dimensional LLL-reduced Bases and the Shortest Vectors. AAAC2018, 2018. (presented by the first author)
- A. Takayasu. Parameter Selections for Approximate GCD Problems. SCIS/CSS Invited Session in IWSEC 2016, 2016.
- A. Takayasu and N. Kunihiro. Faster LLL Reduction to Break the Security of Fully Homomorphic Encryption and Multilinear Map over the Integers. Poster session in IWSEC 2015, 2015.
- A. Takayasu. Improved Algorithms for Partial Key Exposure Attacks on RSA. SCIS/CSS Invited Session in IWSEC 2014, 2014.
- A. Takayasu and N. Kunihiro. Partial Key Exposure Attacks on RSA When Most Significant Bits of d Known. Poster session in ACM ASIACCS 2014, 2014.
- A. Takayasu and N. Kunihiro. Partial Key Exposure Attacks on RSA: Achieve Boneh-Durfee's Bound. Poster session in IWSEC 2013, 2013.

## Other Talks

Other Talks

- Solving RSA and Factoring Problems Using LLL Reduction. Workshop on analysis of mathematical cryptography via algebraic methods，February 2018．
- Small CRT-exponent RSA Revisited. NTT-JFLI-U.Tokyo Workshop on Cryptography, January 2018.
- Small CRT-exponent RSA Revisited. Tokyo Crypto Day, June 2017.

## Professional Activities

Professional Activities

- Program Committee Member：ACISP2019, Indocrypt2018, ProvSec2018, ACISP2018, ACM APKC2018, ICISC2017