Immobilizer
Immobilizers are devices on motor vehicles that are intended to prevent them from being used without authorization. A distinction is made between mechanical immobilizers and electronic immobilizers. There are also so-called involuntary immobilizers , which are aimed at the owner.
Mechanical immobilizer
- The so-called steering wheel claw is by means of lock on the steering wheel mounted so that it is not possible to turn the steering wheel. In another design, a steel rod is spread between the steering wheel and a pedal so that the pedals cannot be operated either. Although these simple methods are not easy to use, they have the advantage that they are inexpensive and also easily visible, so that casual thieves may be deterred.
- The gear shift lock is firmly connected to the body in the center console using shear bolts. It is blocked by inserting a steel bolt. This blocks the movement of the gear shift in reverse . Even cars with automatic gearshifts can be protected in this way in the P (park) position. The lock is equipped with a hardened lock.
- The OBD saver closes the OBD socket and thus prevents tampering hardware such as B. Keyprogrammer for an empty key or to deactivate the immobilizer. The OBD socket is the access to all electrical components in the vehicle and is used not only for troubleshooting in the workshop but also by car thieves to get to the vehicle quickly and silently. The OBD saver is equipped with a hardened security lock and has the decisive advantage that it remains permanently installed in the vehicle and only has to be dismantled when visiting the specialist workshop (e.g. to read out the fault memory).
Involuntary immobilizer
The so-called valve monitor causes the air in the tires to escape completely after 200 m to 500 m when driving off. This immobilizer is used by city administrations and regulatory agencies to ask customers who are in default to pay (e.g. vehicle tax , warning fines ). However, critics argue that the valve monitor can be a hazard if it is not noticed or the warning attached to the vehicle has been removed, since an empty tire makes it difficult to control the vehicle and can lead to accidents. The major disadvantage of the valve monitor, however, is in particular the possibility of making it inoperable by driving slowly. In order to open the valve, the valve monitor needs a sufficiently strong centrifugal force, but this is only reached from around 15 km / h. So you can continue to move a vehicle locked with a valve guard by driving at walking pace. Furthermore, the valve guard does not prevent the driver from changing the wheel. Many city administrations that have been using the valve monitor for a long time consider this procedure to have failed due to the high number of losses. The trend has been towards parking claws (wheel claws) since around 2005 , which make it impossible to move the vehicle or to change the wheels. For such purposes, wheel clamps are sometimes used, which are clamped and locked over the wheels by the police.
Electronic immobilizer
In most cases, the term immobilizer refers to the legally required electronic immobilizer. This goes back to the initiative of the Allianz Center for Technology , which required manufacturers to install electronic immobilizers according to their standard in the 1990s.
Since January 1, 1998, all newly registered cars in Germany must be equipped with an electronic immobilizer ( Section 38a StVZO ). Other insurance companies had already requested immobilizers and associated deductions in the event of theft, as car thefts increased rapidly, especially after the end of the Cold War .
The immobilizer is activated automatically when the ignition is switched off . Them when switching to put the ignition back out of operation, is usually a RFID chip used. Individual car manufacturers also use key rings with galvanic contacts or a number keypad with a PIN code . Ultimately, passive RFID transponders have become generally accepted in the key.
First generation
The first immobilizer models from around 1991 as well as retrofit systems worked in most cases according to the so-called "three-circle interruption". This usually interrupts via relays :
- the ignition
- the fuel supply
- the starter
The three-circuit break offers only moderate protection and is easy for thieves to overcome, since only the relays have to be bridged again. However, this takes so much time that amateur thieves are deterred.
Second generation
More modern immobilizers (starting around 1994) no longer work with the three-circuit interruption, but give the engine control unit a release via electronic communication, without which the engine will not start. This communication usually takes place via the vehicle bus system (today mostly the CAN bus ) and is more or less strongly encrypted.
The use RFID chips in the keys are simple in most cases read-only - transponder , as they are also used for identification of animals and only a fixed serial number cyclically send in plain text, or rewritable transponders, which are assigned an identification number can .
The immobilizer itself can be an independent control unit or it can be integrated into another, in the majority of vehicles in the instrument cluster or the on-board computer .
Third generation
With current third-generation immobilizers, both the communication between the RFID transponder and the immobilizer to authenticate the authorized driver using his or her key, and the communication between the immobilizer and the engine control unit to enable the vehicle, are cryptographically secured.
Alcolock
An alcolock is the technical connection between an electronic immobilizer and a device for determining breath alcohol . It is intended to prevent driving under the influence of alcohol by means of an ignition lock.
See → main article: Alcohol ignition lock
outlook
The race between car thieves and car manufacturers will probably continue and the systems for theft protection will have to be further developed. To be emphasized are:
- Immobilizers with even deeper integration into the vehicle electronics, so that a stolen vehicle becomes virtually worthless
- Alarm systems to deter the thief
- Systems for the recovery of stolen vehicles via GPS and GSM
In addition to electronic components, immobilizer systems also contain hard-wired software and can represent company trade secrets. Under certain conditions, the possession and use of devices with which such systems can be overcome is therefore punishable in many countries, in Germany for example under Section 17 UWG or Section 263a StGB .
In the fourth generation of the immobilizer, electronic chips are integrated in the key or in the speedometer . This chip contains a digital key without which the car cannot be started. An algorithm checks the correctness of the key. The vehicle can only be started if it is correctly identified.
The problem here is that, according to security experts, it is usually a repeatable key that is easily recorded by thieves or wireless keyloggers today when opening the car, while they block the signal to close the car with a jammer . The solution to this is likely to be the next generation of systems that work with one-time pad random codes generated by the car - out of a secure box , which are periodically transferred into the key and B. are only valid once for every minute of the day.
In principle, however, the car key could also store enough one-time pad codes ex works, which would last for the entire life of the car, especially since the GByte-sized data storage chips required for this now only cost cents.
There is a large trade in technical spare parts and reprogrammed control units at home and abroad. Following the fourth-generation immobilizer, fifth-generation immobilizers are now installed in modern vehicles. Since there are now some foreign companies that specialize in overcoming immobilizers, it is only a matter of time before this technology is also obsolete.
Legal
Carrying a device to overcome electronic immobilizers can be a criminal offense.
literature
- Hans-Hermann Braess, Ulrich Seiffert: Vieweg manual automotive technology. 2nd edition, Friedrich Vieweg, Braunschweig / Wiesbaden 2001, ISBN 3-528-13114-4
- Peter A. Wellers, Hermann Strobel, Erich Auch-Schwelk: Vehicle technology expertise. 5th edition, Holland + Josenhans, Stuttgart 1997, ISBN 3-7782-3520-6
- Kurt-Jürgen Berger, Michael Braunheim, Eckhard Brennecke: Technology automotive engineering. 1st edition, Verlag Gehlen, Bad Homburg vor der Höhe 2000, ISBN 3-441-92250-6