[Cryptography] Can someone explain small order subgroups?

[Viktor Dukhovni]

> On Mar 7, 2017, at 10:37 AM, Phillip Hallam-Baker <phill at hallambaker.com> wrote:
> 
> I was trying to work out quite why my code was behaving oddly and then I discovered that I was calculating the order of the group wrongly.

Perhaps these will help:

https://en.wikipedia.org/wiki/Counting_points_on_elliptic_curves#Schoof.E2.80.93Elkies.E2.80.93Atkin_algorithm
https://en.wikipedia.org/wiki/Schoof%E2%80%93Elkies%E2%80%93Atkin_algorithm

-- 
	Viktor.