I also forgot to mention that for b it's always the largest prime factor of u.
Alright, I've spent all of the last thirteen hours working on this, despite the fact that I have more non-VQC-related work to do this week than I probably had time for before I spent an entire day on this. I need a break. Seriously, please, can somebody else work on this grid pattern thread with me? Why am I the only one working on it? I'm up to around the start of RSA #7. Here's the thread >>6506