re more technical details encrypted under k then k will be encrypted under the unit key uk and the serial number of the unit added to produce a three part message which will then be encrypted under the system key sk producing e e m k e k uk serial number sk my understanding is that e m k is not encrypted under sk called the family key and that the decrypt key corresponding to sk is held by law enforcement does anyone have first hand knowledge on this i will also check it out but this is am sunday so i did not want to wait ok so there are in fact two distinct components transmitted by the chip the real message encrypted with the conventional key and the serial number and encrypted conventional key encrypted with the imho kind of bogus as the whole concept of one key that millions of people use which can t be changed doesn t seem reasonable family key suppose i analyze the output of this chip and i m able to determine which bits are the encrypted packet which contains the serial number and session key suppose i also design a simple algorithm based on this information which takes the data containing the encrypted session key and twiddles a bit or several before it s sent down the line mind you i m sure the nsa thought of this along with a dozen other attacks i can t imagine and the system is probably somehow designed so that manipulation of this information will cause a compliant receiving chip to somehow fail to decrypt successfully but how what if the two parties agree in advance on some kind of consistent bit twiddling scheme so the decryption chip sees the restored proper bitstream but an eavesdropper gets a e k uk packet that s wrong i suppose this could be easily defeated if the chip sends that information out many times in slightly different ways making it effectively impossible to be certain you know all the information being sent marc vanheyningen mvanheyn cs indiana edu mime ripem accepted if your theory predicts different outcomes depending on whether you use discrete mathematics or continuous mathematics then you ve got the wrong theory bruce maclennan
