Abstract : The security of torus-based and pairing-based cryptography relies on the difficulty of computing discrete logarithms in small degree extensions of finite fields of large characteristic. It has already been shown that for degrees 2 and 3, the discrete logarithm problem is not as hard as once thought. We address the question of degree 6 and aim at providing real-life timings for such problems. We report on a record DL computation in a 132-bit subgroup of $GF(p^6)$ for a 22-decimal digit prime, with $p^6$ having 422 bits. The previous record was for a 79-bit subgroup in a 240-bit field. We used NFS-DL with a sieving phase over degree 2 polynomials, instead of the more classical degree 1 case. We show how to improve many parts of the NFS-DL algorithm to reach this target.
https://hal.inria.fr/hal-01624662 Contributor : Laurent GrémyConnect in order to contact the contributor Submitted on : Thursday, October 26, 2017 - 4:03:48 PM Last modification on : Thursday, January 20, 2022 - 5:26:31 PM Long-term archiving on: : Saturday, January 27, 2018 - 2:01:54 PM