Paper 2013/095 Original: eprint.iacr.org/2013/095 ↗

A new index calculus algorithm with complexity $L(1/4+o(1))$ in very small characteristic

Antoine Joux
Abstract

In this paper, we describe a new algorithm for discrete logarithms in small characteristic. This algorithm is based on index calculus and includes two new contributions. The first is a new method for generating multiplicative relations among elements of a small smoothness basis. The second is a new descent strategy that allows us to express the logarithm of an arbitrary finite field element in terms of the logarithm of elements from the smoothness basis. For a small characteristic finite field of size $Q=p^n$, this algorithm achieves heuristic complexity $L_Q(1/4+o(1)).$ For technical reasons, unless $n$ is already a composite with factors of the right size, this is done by embedding $\GF{Q}$ in a small extension $\GF{Q^e}$ with $e\leq 2\lceil \log_p n \rceil$.

Metadata
Available format(s)
PDF
Category
Foundations
Publication info
Preprint.
History
2013-07-24: last updated
2013-02-21: published
Short URL
https://ia.cr/2013/095
License
https://creativecommons.org/licenses/by/4.0/

BibTeX

@misc{cryptoeprint:2013/095,
      author = {Antoine Joux},
      title = {A new index calculus algorithm with complexity $L(1/4+o(1))$ in very small characteristic},
      howpublished = {Cryptology {ePrint} Archive, Paper 2013/095},
      year = {2013},
      url = {https://eprint.iacr.org/2013/095}
}
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