Yasufumi Hashimoto

Affiliation
    Department of Mathematical Sciences, University of the Ryukyus
    Nishihara-cho, Okinawa 903-0213, JAPAN
    TEL: +81-98-895-8504
    E-mail: hashimoto(at)math.u-ryukyu.ac.jp
Education
    B.E. degree, Kyushu University, 2001.
    M.E. degree, Kyushu University, 2003.
    Doctor degree (Mathematics), Kyushu University, 2006.
Business Experience
    JSPS Research Fellow (DC2), Kyushu University, April 2005 -- March, 2007.
    COE Postdoctral Research Fellow, Kyushu University, April 2007 -- July, 2007.
    Researcher, Institute of Systems & Information Technologies (ISIT), July 2007 -- March 2011.
    Lecturer (part-time), Kyushu University, April 2009 -- March 2011.
    Assistant Professor, University of the Ryukyus, April 2011 -- May 2016.
    Guest Professor, Kyushu University, April 2011 -- March 2019.
    Associate Professor, University of the Ryukyus, June 2016 -- Now.

Works
Papers (referred)
  1. Y. Hashimoto, Square integrals of the logarithmic derivatives of Selberg's zeta functions in the critical strip, arXiv:2112.07816 [math.NT] (2021), to appear in Internat. J. Number Theory.
  2. Y. Hashimoto, Solving the problem of Blockwise Isomorphism of Polynomials with Circulant matrices, to appear in IEICE Trans. Fundamentals.
  3. Y. Hashimoto, Key recovery attack on Hufu-UOV, JSIAM Letters, Vol. 14 (2022), pp.1--4.
  4. Y. Hashimoto, Selberg's zeta function for the modular group in the critical strip, Math. Nachr., Vol. 294 (2021), pp. 1899--1904.
  5. Y. Hashimoto, Asymptotic behaviors of class number sums associated with Pell-type equations, Math. Z., Vol. 292 (2019), pp.641--654.
  6. Y. Hashimoto, Key recovery attack on Circulant UOV/Rainbow, JSIAM Letters, Vol.11 (2019), pp.45--48.
  7. Y. Hashimoto, Y. Ikematsu, T. Takagi, Chosen Message Attack on Multivariate Signature ELSA at Asiacrypt 2017, Journal of Information Processing, Vol. 27 (2019), pp.517--524, Recommended Paper, Specially Selected Paper.
  8. Y. Hashimoto, High-rank attack on HMFEv, JSIAM Letters, Vol.10 (2018), pp.21--24.
  9. Y. Hashimoto, Multivariate public key cryptosystems, Mathematical Modelling for Next-Generation Cryptography, pp. 17--42, Springer, 2017.
  10. Y. Hashimoto, Chosen ciphertext attack on ZHFE, JSIAM Letters, Vol.9 (2017), pp.21--24.
  11. Y. Hashimoto, Key recovery attacks on multivariate public key cryptosystems derived from quadratic forms over an extension field, IEICE Trans. Fundamentals, Vol. 100-A (2017), pp.18--25.
  12. Y. Hashimoto, Cryptanalysis of the multivariate sigature scheme proposed in PQCrypto 2013, IEICE Trans. Fundamentals, Vol. E99-A (2016), pp.58--65.
  13. Y. Hashimoto, Cryptanalysis of the quaternion Rainbow, IEICE Trans. Fundamentals, Vol. E98-A (2015), pp.144--152.
  14. H. Miura, Y. Hashimoto, T. Takagi, Extended algorithm for solving underdefined multivariate quadratic equations, IEICE Trans. Fundamentals, E97-A (2014), pp.1418--1425.
  15. Y. Hashimoto, Correlations of multiplicities in length spectra for congruence subgroups, Bull. London Math. Soc., Vol. 45 (2013), pp. 175--190.
  16. Y. Hashimoto, Asymptotic formulas for class number sums of indefinite binary quadratic forms in arithmetic progressions, Internat. J. Number Theory, Vol. 9 (2013), pp. 27--51.
  17. Y. Hashimoto, T. Takagi et al., General fault attacks on multivariate public key cryptosystems, IEICE Trans. Fundamentals, Vol. E96-A (2013), pp.196--205.
  18. Y. Hashimoto, Algorithms to solve massively under-defined systems of multivariate quadratic equations, IEICE Trans. Fundamentals, Vol. E94-A (2011), pp. 1257--1262.
  19. Y. Hashimoto, Partial zeta functions, Archiv der Mathematik, Vol. 95 (2010), pp.363-372.
  20. Y. Hashimoto, On asymptotic behavior of composite integers n=pq, J. Math-for-Industry, Vol. 1(2009), pp.45-49.
  21. Y. Hashimoto, M. Wakayama, Splitting density for lifting about discrete groups, Tohoku Math. J., Vol. 59 (2007), pp.527-545.
  22. Y. Hashimoto, Arithmetic expressions of Selberg's zeta functions for congruence subgroups, J. Number Theory, Vol. 122 (2007), pp.324-335.
  23. Y. Hashimoto, M. Wakayama, Hierarchy of the Selberg zeta function, Lett. Math. Phys., Vol. 73 (2005), pp.59-70.
  24. Y. Hashimoto, Special values of the spectral zeta functions for locally symmetric Riemannian manifolds, J. Math. Soc. Japan, Vol. 57 (2005), pp.217-232.
  25. Y. Hashimoto, Euler constants of Euler products, J. Ramanujan Math. Soc., Vol. 19 (2004), pp.1-14.
  26. Y. Hashimoto, Y. Iijima, N. Kurokawa, M. Wakayama, Euler's constants for the Selberg and the Dedekind zeta functions, Bull. Belg. Math. Soc. Simon Stevin, Vol. 11 (2004), pp.493-516.
  27. Y. Hashimoto, The Euler-Selberg constants for nonuniform lattices of rank one symmetric spaces, Kyushu J. Math., Vol. 57 (2003), pp.347-370.
Proceedings (referred)
  1. Y. Hashimoto, Solving the problem of Blockwise Isomorphism of Polynomials with Circulant matrices, Springer LNCS Vol. 12835 (2021), pp.137--150, Best Paper Award of IWSEC 2021.
  2. Y. Hashimoto, Recent developments in multivariate public key cryptosystems, International Symposium on Mathematics, Quantum Theory, and Cryptography, pp.209--229, Springer, 2020.
  3. Y. Hashimoto, Y. Ikematsu, T. Takagi, Chosen Message Attack on Multivariate Signature ELSA at Asiacrypt 2017, Springer LNCS Vol. 11049 (2018), pp.3--18, Best Paper Award of IWSEC 2018.
  4. C.M. Cheng, Y. Hashimoto, H. Miura and T. Takagi, A polynomial-time algorithm for solving a class of underdetermined multivariate quadratic equations over fields of odd characteristics, Springer LNCS Vol. 8772 (2014), pp.40--58.
  5. Y. Hashimoto, Cryptanalysis of the multivariate sigature scheme proposed in PQCrypto 2013, Springer LNCS Vol. 8772, (2014), pp.108--125.
  6. Y. Hashimoto, Cryptanalysis of the quaternion Rainbow, Springer LNCS 8231 (2013), pp.244--257.
  7. H. Miura, Y. Hashimoto, T. Takagi, Extended Algorithm for Solving Underdefined Multivariate Quadratic Equations, Springer LNCS 7932 (2013), pp.118--135.
  8. Y. Hashimoto, T. Takagi et al., General fault attacks on multivariate public key cryptosystems, Springer LNCS 7071 (2011), pp.1--18.
  9. Y. Hashimoto, On small secret key attack against RSA with high bits known prime factors, Proceedings (short papers) of 5th International Workshop on Security (IWSEC2010), pp. 14-25.
  10. Y. Hashimoto, Algorithms to solve massively under-defined systems of multivariate quadratic equations, Proceedings (Industrial Track) of the 8th International Conference on Applied Cryptography and Network Security, pp.26--37, 2010.
  11. Y. Hashimoto, Prime and zero distributions for meromorphic Euler products, 5th Asian Mathematical Conference Proceedings, Vol. 1, pp.255 - 261, 2009.
  12. Y. Hashimoto, Distributions of multiplicities in length spectra for hyperbolic Riemann surfaces,Complex Analysis and its Applications, Proceedings of the 15th International Conference on Finite or Infinite Dimensional Complex Analysis and Applications, OCAMI Studies, Vol. 2-2 (2008), pp.195-199.
  13. Y. Hashimoto,Analytic properties of partial zeta functions, RIMS Kokyuroku Bessatsu, Vol. B-7 (2008), pp. 73-82.
Papers and Preprints (unreferred)
  1. Y. Hashimoto, An elementary construction of QR-UOV, https://eprint.iacr.org/2022/145 (2022).
  2. Y. Hashimoto, Vulnerability of Diene-Thabet-Yusuf's cubic multivariate signature scheme, Ryukyu Mathematical Journal Vol.34 (2021), p.1--5.
  3. Y. Hashimoto, On the modifier Q for multivariate signature schemes, https://eprint.iacr.org/2021/1046 (2021).
  4. Y. Hashimoto, Minor improvements of algorithm to solve under-defined systems of multivariate quadratic equations, https://eprint.iacr.org/2021/1045 (2021).
  5. Y. Hashimoto, A note on the multivariate cryptosystem based on a linear code, https://eprint.iacr.org/2019/1396 (2019).
  6. Y. Hashimoto, Recent developments in multivariate public key cryptosystems, MI Lecture Notes Vol. 81 (2019), p.187 - 205.
  7. Y. Hashimoto, On the security of Zhang-Tan's variants of multivariate signature schemes, Ryukyu Mathematical Journal Vol.31 (2018), p.1 -5.
  8. Y. Hashimoto, Weaknesses of cubic UOV and its variants, Ryukyu Mathematical Journal Vol.30 (2017), p.1 -7.
  9. Y. Hashimoto, A note on Tensor Simple Matrix encryption scheme, https://eprint.iacr.org/2016/065 (2016).
  10. Y. Hashimoto, On multiplicities of length spectra for congruence subgroups, Proceedings of Symposium on Representation Theory 2010,, pp.66-81.
  11. Y. Hashimoto, Power sums of length multiplicities for Riemann surfaces, Proceedings of Symposium on Representation Theory 2006, pp.31-45.
  12. Y. Hashimoto, Analytical properties of partial Selberg zeta functions, Proceedings of Symposium on Representation Theory 2005, pp.176-181.
  13. Y. Hashimoto, Ramification density of primitive elements for discrete groups, Proceedings of Symposium on Representation Theory 2004, p.124-131.
  14. Y. Hashimoto, Special values of the spectral zeta functions for locally symmetric Riemannian manifolds, Proceedings of Symposium on Representation Theory 2002, pp.1-13.
  15. Y. Hashimoto, The Euler-Selberg constants for nonuniform lattices of rank one symmetric spaces, Proceedings of Symposium on Representation Theory 2002, p.91-110.
Presentations (referred)
  1. Solving the problem of Blockwise Isomorphism of Polynomials with Circulant matrice, 16th International Workshop on Security (IWSEC2021), Tokyo (Online), Sep. 2021.
  2. Recent developments in multivariate public key cryptosystems, International Symposium on Mathematics, Quantum Theory and Cryptography (MQC 2019), Kyushu University, Sep. 2019.
  3. Chosen Message Attack on Multivariate Signature ELSA at Asiacrypt 2017, (presented by Y. Ikematsu), The 13th International Workshop on Security (IWSEC 2018), Tohoku University, Sep. 2018.
  4. Cryptanalysis of the multivariate sigature scheme proposed in PQCrypto 2013, Sixth International Conference on Post-Quantum Cryptography, University of Waterloo (Canada), Oct. 2014.
  5. A polynomial-time algorithm for solving a class of underdetermined multivariate quadratic equations over fields of odd characteristics, (presented by C.M. Cheng), Sixth International Conference on Post-Quantum Cryptography, University of Waterloo (Canada), Oct. 2014.
  6. Cryptanalysis of the quaternion Rainbow, 8th International Workshop on Security, IWSEC2013, Okinawa, Japan, Nov. 2013.
  7. Extended Algorithm for Solving Underdefined Multivariate Quadratic Equations (presented by H. Miura), Fifth International Conference on Post-Quantum Cryptography, Xlim (Limoges, France), June 2013.
  8. General fault attacks on multivariate public key cryptosystems, Fourth International Conference on Post-Quantum Cryptography, Taipei, Taiwan, Nov.-Dec. 2011.
  9. On small secret key attack against RSA with high bits known prime factors, 5th International Workshop on Security (IWSEC2010), Kobe, Japan, Nov. 2010.
  10. Y. Hashimoto, Distributions of length multiplicities for Riemann surfaces, DMHF 2007: COE Conference on the Development of Dynamic Mathamatics with High Functionality,Book of Abstacts (2007), pp.81--82.