On p-adic Point Counting Algorithms for Elliptic Curves over Finite Fields

  • Authors:
  • Takakazu Satoh

  • Affiliations:
  • -

  • Venue:
  • ANTS-V Proceedings of the 5th International Symposium on Algorithmic Number Theory
  • Year:
  • 2002

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Abstract

Let p be a prime and let q := pN. Let E be an elliptic curve over Fq. We are interested in efficient algorithms to compute the order of the group E(Fq) of Fq-rational points of E. An l-adic algorithm, known as the SEA algorithm, computes #E(Fq) with O((log q)4+驴) bit operations (with fast arithmetic) and O((log q)2) memory. In this article, we survey recent advances in p-adic algorithms. For a fixed small p, the computational complexity of the known fastest p-adic point counting algorithm is O(N3+驴) in time and O(N2) in space. If we accept some precomputation depending only on p and N or a certain restriction on N, the time complexity is reduced to O(N2.5+驴) still with O(N2) space requirement.