Hi, I'm thinking of making a electronic key and lock, where the communication is one way only, ie; from key to lock. Probably InfraRed.
It is important the system cannot be broken by snooping. For instance if someone records a previous successful communication, and replays it, it will not open the lock a second time.
There are a number of ways this can be done with "rolling codes" where the code changes (increments) each time it is used, and previous codes become invalid.
One of the complications is that it would be nice to have more than 1 key device, ie for two different users. So the rolling code incrementation must not cause conflicts between multiple users.
If anyone has done a simple rolling code type implementation I would love to hear from you re how it worked, or potential issues etc.
It is important the system cannot be broken by snooping. For instance if someone records a previous successful communication, and replays it, it will not open the lock a second time.
There are a number of ways this can be done with "rolling codes" where the code changes (increments) each time it is used, and previous codes become invalid.
One of the complications is that it would be nice to have more than 1 key device, ie for two different users. So the rolling code incrementation must not cause conflicts between multiple users.
If anyone has done a simple rolling code type implementation I would love to hear from you re how it worked, or potential issues etc.