Kummer surfaces for primality testing Eduardo Ru´ız Duarte & Marc Paul Noordman Universidad Nacional Aut´onoma de M´exico, University of Groningen
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[email protected] Abstract We use the arithmetic of the Kummer surface associated to the Jacobian of a hyperelliptic curve to study the primality of integersof the form 4m25n 1. We providean algorithmcapable of proving the primality or compositeness of most of the− integers in these families and discuss in detail the necessary steps to implement this algorithm in a computer. Although an indetermination is possible, in which case another choice of initial parameters should be used, we prove that the probability of reaching this situation is exceedingly low and decreases exponentially with n. Keywords: Primality, Jacobians, Hyperelliptic Curves, Kummer Surface 2020 MSC: 11G25, 11Y11, 14H40, 14H45 Introduction Determining the primality of an arbitrary integer n is a fundamental problem in number theory. The first deterministic polynomial time primality test (AKS) was developed by Agrawal, Kayal and Saxena [3]. Lenstra and Pomerance in [25] proved that a variant of AKS has running time (log n)6(2+log log n)c where c isaneffectively computablereal number. The AKS algorithm has more theoretical relevance than practical. If rather than working with general integers, one fixes a sequence of integers, for example Fermat or Mersenne numbers, one can often find an algorithm to determine primality using more efficient methods; for these two examples P´epin’s and Lucas-Lehmer’s tests respectively provide fast primality tests. Using elliptic curves, in 1985, Wieb Bosma in his Master Thesis [5] found analogues of Lucas tests for elements in Z[i] or Z[ζ] (with ζ a third root of unity) by replacing the arithmetic of (Z/nZ)× with the arithmetic of elliptic curves modulo n with complex multiplication (CM).