Huh. I had not though of the rekeying issues before. Glaringly obvious in hindsight. The question of "how can you ensure that this system will not be rekeyed to

Huh. I had not though of the rekeying issues before. Glaringly obvious in hindsight. The question of "how can you ensure that this system will not be rekeyed to respond to someone else" is a great one. The best answer is "there is nothing that can be rekeyed."