[Cryptography] open questions in secure protocol design?

[Tom Ritter]

10. Which Anti-Replay Mechanism?
11. Clocks or no?
12. Authentication Model (CAs? Namecoin? Perspective? WoT? Pre-Shared Keys?)
13. State vs Statelessness

And if you want to get fancy, things like authenticated downtime.

In particular, the ones I see the most teeth-gnashing with is figuring
out anti-replay and state (especially on those damned IoT things).

-tom