Do you know how do I find this principal polarisation explicitly when working with the Jacobian of a hyperelliptic curve over a finite field?, In fact… I have found the equation of an affine part of a genus 2 hyperelliptic curve, What I need is to twist the Jacobian, any useful theorems? , I need to work with the endomorphisms of the curve explicitly, I think Torellis theorem work over every perfect field, but I need to build the thing explicitly.
Thanks and great blog , here is mine but in spanish http://b3ck.blogspot.nl

]]>