International Workshop on Public Key Cryptography

PKC 2010: Public Key Cryptography – PKC 2010 pp 351-367

Solving a 676-Bit Discrete Logarithm Problem in GF(36n)

  • Takuya Hayashi
  • Naoyuki Shinohara
  • Lihua Wang
  • Shin’ichiro Matsuo
  • Masaaki Shirase
  • Tsuyoshi Takagi
Conference paper

DOI: 10.1007/978-3-642-13013-7_21

Volume 6056 of the book series Lecture Notes in Computer Science (LNCS)

Abstract

Pairings on elliptic curves over finite fields are crucial for constructing various cryptographic schemes. The ηT pairing on supersingular curves over GF(3n) is particularly popular since it is efficiently implementable. Taking into account the Menezes-Okamoto-Vanstone (MOV) attack, the discrete logarithm problem (DLP) in GF(36n) becomes a concern for the security of cryptosystems using ηT pairings in this case. In 2006, Joux and Lercier proposed a new variant of the function field sieve in the medium prime case, named JL06-FFS. We have, however, not yet found any practical implementations on JL06-FFS over GF(36n). Therefore, we first fulfill such an implementation and we successfully set a new record for solving the DLP in GF(36n), the DLP in GF(36·71) of 676-bit size. In addition, we also compare JL06-FFS and an earlier version, named JL02-FFS, with practical experiments. Our results confirm that the former is several times faster than the latter under certain conditions.

Keywords

function field sievediscrete logarithm problempairing-based cryptosystems
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Copyright information

© Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • Takuya Hayashi
    • 1
  • Naoyuki Shinohara
    • 2
  • Lihua Wang
    • 2
  • Shin’ichiro Matsuo
    • 2
  • Masaaki Shirase
    • 3
  • Tsuyoshi Takagi
    • 1
  1. 1.Graduate School of MathematicsKyushu UniversityFukuokaJapan
  2. 2.Information Security Research CenterNational Institute of Information and Communications TechnologyTokyoJapan
  3. 3.School of Systems Information ScienceFuture University HakodateHokkaidoJapan