Is it safe to learn new keyfob by its normal open code (rolling-code)?
Part of a wireless door opener, the receiver Doorhan DHRE-2 works, according to description, with the rolling code. It looks like the receiver can register a new keyfob by listening to its normal opening code:
2) To record the new code hold down for 3 sec the key «SW1» on the
recipient card, to make settings of the electric operator connected to the
output CH1 and the key «SW2» – to make settings of the electric operator
connected to the output CH2, at that the indicator LED1 will light. After
that press the necessary key on the remote control unit for 2-3 sec.
Attention! after the operation is completed only one key can be stored in the
memory of the recipient.
It is not necessary to, for example, hold both buttons at the same time to transmit the secret.
This doesn’t make sense to me. The receiver is supposed to be able to calculate next codes from last received code and some pre-shared secret, which is also stored on the keyfob. Does it learn the secret by listening to the normal open code, which is transmitted while you hold the open button for 3 seconds? Then why can’t a thief do that?
Continue reading Is it safe to learn new keyfob by its normal open code (rolling-code)?