Modular polynomials on Hilbert surfaces

Enea Milio (1) , Damien Robert (2)

1 CARAMBA - Cryptology, arithmetic : algebraic methods for better algorithms
2 LFANT - Lithe and fast algorithmic number theory

We describe an evaluation/interpolation approach to compute modular polynomials on a Hilbert surface, which parametrizes abelian surfaces with maximal real multiplication. Under some heuristics we obtain a quasi-linear algorithm. The corresponding modular polynomials are much smaller than the ones on the Siegel threefold. We explain how to compute even smaller polynomials by using pullbacks of theta functions to the Hilbert surface.

Domaines: Mathématiques [math]

Enea Milio, Damien Robert. Modular polynomials on Hilbert surfaces. Journal of Number Theory, 2020, 216, pp.403-459. ⟨10.1016/j.jnt.2020.04.014⟩. ⟨hal-01520262v3⟩