next topic »

[Reply #15 on:]

It makes the whole thing harder, but if I were going to do this, I'd throw a PC into the mix. Let the PC manage the codes, so it can change them when necessary and report them when they need to be sent to a customer. The arduino in the machine can periodically poll the PC for the latest set over wifi, hard wired ethernet or xBee.

[Reply #16 on:]

Each cabin will start with a different random number.  Either every time the key is taken, or depending on the day, increment the secret number by your master number.  My preference would be to increment all cabins at 3am, regardless of whether the key was taken or not.  You could use a different interval for each cabin if you wanted to be more secure.  You could even change the master numbers every week or month in a predictable manner.  The most secure would be to create a loop of about 10 random integers for each cabin.  All of this can be modified and improved after you get the hardware working.  Start simple with the cabin number as the code, incrementing them by the same master at 3am?

[Reply #17 on:]

increment all cabins at 3am, regardless of whether the key was taken or not. 

A customer arriving at 3:05am, due to an unexpected delay, would be rather angry that he couldn't get his key and procede to wake up the OP, which the keybox is designed to avoid!
A better time to change the code would be at 9am.