I’m curious, for a non-network connected lock, how could you ensure that it’s secured with time bound parameters like they list?

Now that I’m thinking about it I guess each lock would have a private key and a CMOS of sorts to keep time. The writer could then write have the public key of each room and that could have a timestamp as part of the encrypted payload. I guess to take it further you could reverse it too with that payload having a private key of the writer and the locks could verify the private key against a public key of the writer. At that point each writer would have to have the public key of all locks, and each lock would have the public key of each writer.

At that point your payload to encode would be a timestamp of expiration and any sort of “checksum” or PSK to verify it was made by a valid writer?