IDK if this is relevant or not. But, Seagate's standard "Barracuda" HDD's don't support encryption! Or so Seagate says. I don't need it, nor would I want it, since it would, (I think), make swapping drives between machines nigh on impossible. (Again, I think).
but if you're looking for encryption software, it might behoove you to find out what Seagate is talking about, or what they mean by their budget line of drives don't support it.
It may mean, their higher line drives have encryption built in to their electronics.
As far as software goes, sorry I can't be of more any help.