This sounds like an interesting project. I've studied quite some category theory myself, though mostly from the "oh pretty!" point of view, and dipped my feet into algebraic geometry because it sounded cool. I think that reading algebraic geometry with the sight set on cryptography would be more giving than the general swimming around in its sea that I've done before. So if you want a reading buddy, do tell. A fair warning though: I'm quite time limited these coming months, so will not be able to keep a particularly rapid pace.