Re: IHU validation in 9-5

Posted by Karlis on Feb 15, 2017; 9:57pm
URL: http://bluesaab-forum.90.s1.nabble.com/IHU-validation-in-9-5-tp990p992.html

There are two players in this case: DICE and TWICE. DICE checks for physical existence of IHU and other nodes on the bus, TWICE checks for security settings/marriage status of a node.

I've done some sniffing of TWICE to figure out how the negotiations between it and the transponder unit are being done to implement car lock/unlock via BlueSaab. It looks pretty straight forward apart from the part where on every acknowledgment by TWICE (?) there's a checksum (that gets calculated in a certain way I haven't been able to crack yet) that get's put into a CAN frame and tells the transponder "ok, we're good, let's tell DICE to unlock the doors".

Clear as mud, eh'? :)