From a quick skim, it sounds like you're using the current time (encrypted) to prevent replay attacks. Good, simple...but I'd note that higher up in your descr

From a quick skim, it sounds like you're using the current time (encrypted) to prevent replay attacks. Good, simple...but I'd note that higher up in your description. And at least think about a Plan B, for when things really go sideways, and system clocks get out of sync. Or intruders have a foothold your network infrastructure.