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Traps to the BGJT-algorithm for discrete logarithms

Part of: Computational number theory

Published online by Cambridge University Press:  01 August 2014

Qi Cheng ,
Daqing Wan  and
Jincheng Zhuang
Qi Cheng
Affiliation:
School of Computer Science, University of Oklahoma, Norman, OK, USA email qcheng@cs.ou.edu
Daqing Wan
Affiliation:
Department of Mathematics, University of California, Irvine, CA, USA email dwan@math.uci.edu
Jincheng Zhuang
Affiliation:
School of Computer Science, University of Oklahoma, Norman, OK, USA email jzhuang@ou.edu

Abstract

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In the recent breakthrough paper by Barbulescu, Gaudry, Joux and Thomé, a quasi-polynomial time algorithm is proposed for the discrete logarithm problem over finite fields of small characteristic. The time complexity analysis of the algorithm is based on several heuristics presented in their paper. We show that some of the heuristics are problematic in their original forms, in particular when the field is not a Kummer extension. We propose a fix to the algorithm in non-Kummer cases, without altering the heuristic quasi-polynomial time complexity. Further study is required in order to fully understand the effectiveness of the new approach.

MSC classification

Secondary: 11Y16: Algorithms; complexity

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