RFID Guardian Use-Car Keyless Entry

From RFID Wiki

During 1993, the worldwide increases in automotive theft reached a level which was no longer acceptable for insurance companies. The German in- surance companies forced the rapid introduction of a new security system | an immobilizer, which uses RFID technology. Since the beginning of 1995, nearly all models for the European market are equipped with OEM immo- bilizers. Thefts of vehicles with electronic immobilizers are a tenth of thefts of vehicles without immobilizer.

The basic operation of immobilizer is simple: the door or the engine of the car will not be opened or started unless the user provides its authenti- cation, i.e. a key. However, the details are very complex. In this section, I will brie°y describe how Texas Instruments DST works. The basic idea is to use a challenge/response scheme and a crypto device called Digital Signature Transponder (DST) serves that functionality. Dur- ing initialization, the vehicle security system and the transponder exchange a secret encryption key. The key is not transmitted, only the transponder response to a challenge sent by the transceiver can be over heard.

The response R is a function of the encryption key Ke, the challenge RAND and the cryptographic algorithm Fc. This response is returned to the transceiver using Frequency Shift Keying (FSK). The car security system calculates the expected response using the same algorithm and the same encryption key and compares the response received from the transponder to the calculated one. The calculation of the expected response either can be done in parallel with the communication between transponder and reader or after reception of the transponder response. If expected and calculated responses match, success information will be sent to the engine management computer. In time critical applications, the challenge and the response can be generated after immobilization and stored for the next cycle.

UML Object Model

UML Sequence Model

Sample ACL

##################################
# Car Keyless Entry System Rules
##################################
context trusted;

# By default, we leave RFID traffic alone
rule P15693 ACCEPT
{
	context = *;
	role = *;
	tags = *;
	query = {command = *;};
};

# Block unknown readers to read my keys
rule P15693 DENY
{
	context = *;
	role = *;
	tags = @MY_TAGS;
	query = { command = *; };
};

# However, we should permit the cars
rule P15693 ACCEPT
{
	context = trusted;
	role = LEGAL_READER;
	tags = @MY_TAGS;
	query = { command = *; };
};