Ok, I was thinking, for my security alarm system that I keep annoying people with, that simple serial (RS485, via four MAX485 chips for full duplex communication) may be a little insecure for arming and disarming the alarm. it passes the RFID key and the password key in plain text.
Now, if I could figure out some sort of rolling code…
currently, the protocol between the control panel and master is as follows.
The code (PDF) for the control panel is attached. if need be, I can attach the code for the master controller.
but as can be seen in the protocol, it would be easy to “sniff” the arm and disarm protocol. but if the commands were some sort of rolling code, it would be harder to “sniff”.
Now, I have been perusing a Enigma/Arduino clone, from HERE, and I think it may be a little too complicated for what I want to do.
I suppose if I send an init code to increment the key at the start of a packet, then I can use a simple transposition cipher.
another option might be a time based rolling code. I use a GPS pod for a time base, and it doesn’t currently send to the control panel, but it could be.
then, every hour, on the hour, the code would roll to the next predefined code.
My brain is a bit frazzled from pouring through ideas in my head, and Google.
Any ideas? I’m still searching, but maybe several heads are better than mine. well, that is actually a guarantee, but anyway.
AlarmMaster002_bv4243_001.pdf (86.4 KB)