# An $L (1/3 + \varepsilon)$ Algorithm for the Discrete Logarithm Problem for Low Degree Curves

1 TANC - Algorithmic number theory for cryptology
LIX - Laboratoire d'informatique de l'École polytechnique [Palaiseau], Inria Saclay - Ile de France
2 CACAO - Curves, Algebra, Computer Arithmetic, and so On
INRIA Lorraine, LORIA - Laboratoire Lorrain de Recherche en Informatique et ses Applications
Abstract : The discrete logarithm problem in Jacobians of curves of high genus $g$ over finite fields $\FF_q$ is known to be computable with subexponential complexity $L_{q^g}(1/2, O(1))$. We present an algorithm for a family of plane curves whose degrees in $X$ and $Y$ are low with respect to the curve genus, and suitably unbalanced. The finite base fields are arbitrary, but their sizes should not grow too fast compared to the genus. For this family, the group structure can be computed in subexponential time of $L_{q^g}(1/3, O(1))$, and a discrete logarithm computation takes subexponential time of $L_{q^g}(1/3+\varepsilon, o(1))$ for any positive~$\varepsilon$. These runtime bounds rely on heuristics similar to the ones used in the number field sieve or the function field sieve algorithms.
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Conference papers
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Cited literature [16 references]

https://hal.inria.fr/inria-00135324
Contributor : Andreas Enge <>
Submitted on : Wednesday, March 7, 2007 - 1:46:50 PM
Last modification on : Monday, May 20, 2019 - 2:30:25 PM
Long-term archiving on : Tuesday, April 6, 2010 - 11:18:37 PM

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### Citation

Andreas Enge, Pierrick Gaudry. An $L (1/3 + \varepsilon)$ Algorithm for the Discrete Logarithm Problem for Low Degree Curves. Eurocrypt 2007, May 2007, Barcelona, Spain. pp.379-393. ⟨inria-00135324⟩

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