Ah, I see - thanks for this clarification. Alpha server and Beta server can actually communicate after the initial setup, but I didn't want this to be a conside

Ah, I see - thanks for this clarification. Alpha server and Beta server can actually communicate after the initial setup, but I didn't want this to be a consideration in my scenario, since I don't want any such communication to be required during each permission message transaction (once per hour or day, etc. would of course be fine). Perhaps, I will provide an API method for automatically expiring an HMAC and fetching a new one. During this rollover period, messages sent using the old HMAC will be allowed to fail, since they can just come get a new copy from Alpha server.