In 1965 Hayashida and Nishi initiated the study of genus 2 curves C whose Jacobian JC is isomorphic to a product A = E1×E2 of two elliptic curves. In their papers [15], [17] and [16], they determined the number of curves C with JC ' A for a fixed A in many cases, thereby exhibiting the existence of such curves. A similar count was done for supersingular curves by Ibukiyama, Katsura and Oort[19]...

We prove a higher dimensional generalization of Gross and Zagier’s theorem on the factorization of differences of singular moduli. Their result is proved by giving a counting formula for the number of isomorphisms between elliptic curves with complex multiplication by two different imaginary quadratic fields K and K′, when the curves are reduced modulo a supersingular prime and its powers. Equi...

This paper presents a novel method for designing compact yet efficient hardware implementations of the Tate pairing over supersingular curves in small characteristic. Since such curves are usually restricted to lower levels of security because of their bounded embedding degree, aiming for the recommended security of 128 bits implies considering them over very large finite fields. We however man...

We exhibit the isogeny classes of supersingular abelian threefolds over F2n containing the Jacobian of a genus 3 curve. In particular, we prove that for even n > 6 there always exist a maximal and a minimal curve over F2n . All the curves can be obtained explicitly.