Cover and decomposition index calculus on elliptic curves made practical: application to a previously unreachable curve over Fp6

  • Authors:
  • Antoine Joux;Vanessa Vitse

  • Affiliations:
  • Laboratoire PRISM, DGA and Université de Versailles Saint-Quentin, Versailles Cedex, France;Laboratoire PRISM, Université de Versailles Saint-Quentin, Versailles Cedex, France

  • Venue:
  • EUROCRYPT'12 Proceedings of the 31st Annual international conference on Theory and Applications of Cryptographic Techniques
  • Year:
  • 2012

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Abstract

We present a new "cover and decomposition" attack on the elliptic curve discrete logarithm problem, that combines Weil descent and decomposition-based index calculus into a single discrete logarithm algorithm. This attack applies, at least theoretically, to all composite degree extension fields, and is particularly well-suited for curves defined over Fp6. We give a real-size example of discrete logarithm computations on a curve over a 151-bit degree 6 extension field, which would not have been practically attackable using previously known algorithms.