Car alarm

As a rule, it consists of the main unit, the transceiver (antenna), the key fob, the shock sensor , the limit switch for interior lighting (the sensor for opening doors), the limit switch for the engine compartment (sensor for opening the hood, trunk) of the service button and an indicator in the form of an LED . Car alarms are with feedback, that is, a key fob pager informs about the condition of the car.

Car alarms do not give a 100% guarantee against theft, but significantly reduce the attractiveness of small hijackers.

It is possible to connect a GSM / GPRS module to models of car alarms of the middle and highest price category with the ability to control the alarm functions from a cell phone by sending SMS and receiving notifications. If there is such a module, an additional function may be to determine the location of the car ( GPS / GLONASS ): this information can be accessed on the key fob, cell phone, and with authorization in the smartphone application and on the manufacturer’s website. Other functions of the GSM module can be calls to predefined phone numbers (for events recorded by an alarm), listening to the vehicle interior, diagnostic messages (when the alarm is connected to the car CAN ), monitoring vehicle movements with notification of reaching restricted areas, etc.

For “hacking” (substitution of the code radio transmission) of car alarms, hijackers use code grabbers (“code grabber”, “code grabber”). There are three types of such devices: code grabber for static codes, code grabbers on the principle of code change (for one- and two-button key fobs) and algorithmic (sometimes they are called "manufactory").

For earlier car alarm systems using a static code (see Encryption Algorithms in Car Alarms ), a device that intercepts this code and remembers it is enough.

For codegrabbers, based on the principle of code change, a working algorithm is characteristic that requires the owner to press the keyfob buttons again, using partially jamming and intercepting the keyfob package. Materials on this subject are publicly available ^{[1] [2] [3]} on thematic Internet resources.

Algorithmic code grabber - a device that recognizes the type (that is, manufacturer, "brand") of an alarm by digitally sending the key fob and, using the so-called "manufactory code", becomes a clone (full duplicate) of the owner's key fob. This principle applies to car alarms that use the KeeLoq algorithm ^{[4] [5]} and others to encode the signal from the key fob to the central signaling unit and during keychain – central unit radio communication (dialogue systems) ^[6] .

It should be understood that in many respects the hype about hacks by a code grabber of one or another model is caused by unfair competition of signaling importers and Russian “manufacturers” collectors.

Dialog Code

Dialog code is a special method of code protection of car alarms, invented by Magic Systems . It uses authentication technology through an insecure channel, widely known in cryptography, to identify the key fob.

Having received a signal, the system is convinced that it was sent from "its" keyring, and this does not happen once, but in a dialogue. In response to the first signal, the system sends a request to the key fob in the form of a pseudo-random number, which is processed by the key fob using a special algorithm and sent back. The alarm processes its package using the same algorithm, comparing the received response with its data. If they match, the command is executed, and confirmation is sent to the key fob.

The interactive code provides additional protection against electronic hacking.

Also, alarms are often equipped with an auto-start function of the engine, which can be made:

• manually (remote start);
• at specified intervals (periodic start);
• upon reaching the set time (alarm);
• upon reaching the user-specified (or lower) temperature.

It can be connected with autostart or separately:

• Heated seats and windows
• select “driver profile”: seat height, steering column extension, multimedia center mode

etc.

In addition, when arming, additional functions may include:

• hatch and door glass closure
• folding mirrors
• “Light path” (turning on the light for a few seconds for the driver to get to the house)

etc.

• Encryption Algorithms in Car Alarms
• Multilock
• Anti-theft system
• Car immobilizer