I have just update my network to mysensors 2.0 and my network is growing up. I think its time to secure it. First, I've changed the channel of RF24, then I've uncommented the line "//#define MY_RF24_ENABLE_ENCRYPTION" in MyConfig.h file.
It's also noticed "and all must be personalized with the same AES key". But where can I setup this AES key and which format for it ?