Imagine: you return from the store, and your car is standing with an open door, and things have disappeared from the cabin. Or worse — the car is not there at all. To prevent such scenarios from becoming reality, let's figure out how modern security systems work, how much we can trust them, and whether we are throwing money away.
Let's make a reservation right away: in this material, we will not delve into the technical details of alarm devices, but will focus on the general principle of their operation. In the following articles, we will take a closer look at code grabbers and the internal structure of security systems.
Any alarm system includes the following basic set of elements:
• blocking relay;
• start relay;
• shock sensor;
• LED;
• siren;
• interior volume sensor;
• communication wires;
• key fob communicator
The central unit is responsible for starting the engine and controlling arming/disarming of the vehicle.
The shock sensor reacts to mechanical impacts, such as blows or shaking of the body.
The interior volume sensor connects to the shock sensor connector and reacts to air fluctuations in the cabin. It is worth noting that this sensor is not included in the basic package of many alarm systems.
The siren is a device that needs no introduction and is present in any security system.
The key fob communicator is, in fact, a remote control. Modern models offer a wide range of programmable functions, depending on the specific model. Communication between the key fob and the central unit is carried out via a radio channel using a coded signal. It is this aspect that is most important to us. If you gain access to the radio channel and decipher the code, you can gain control over the alarm. But we will talk about this later.
Often, additional engine blocking systems are installed along with the alarm.
How a security system works
Let's clarify right away: we provide general information about the principles of security systems, explaining everything in simple words. After reading this material, you will not be able to hack someone else's car, and, by the way, your own either. However, this basic knowledge will help you make an informed choice when buying an alarm.
The radio alarm key fob operates at a frequency of 433.92 MHz. Each alarm has a unique code that is used to recognize the key fob.
This option is the least protected against hacking. To get into a car with such a system, it is enough to intercept the radio signal from the key fob and record it. It is impossible to do this without special equipment. Therefore, attackers use either scanners or code grabbers.
A scanner is a device that iterates through and reproduces codes in the format of a specific alarm. However, many modern systems are protected against scanning. They have a timeout after entering an incorrect code, which blocks further attempts. The lock can only be removed by repeatedly transmitting the correct code. In this case, the scanner becomes useless, and criminals have to use a code grabber.
However, anti-scanning systems are not protected against intercepting the signal from the air. It is enough to receive and record the signal with the code at the moment when the owner arms the car. For this, a device called a code grabber is used. It works like a radio receiver at the key fob frequency. After recording the code, the device switches to transmitter mode and sends a signal to unlock the car.
How to protect against a code grabber?
Alarm manufacturers have introduced a code-changing algorithm into signal coding, which is called dynamic. Each time you press a button on the key fob, the code changes, which makes the use of code grabbers pointless. A previously recorded code will not work, since it is already outdated and invalid.
The most common systems use encoding/decoding keys with a 64-bit combination. The code is formed based on the serial number and a 64-bit key. The key is never transmitted over the air and is stored in the device's memory. The key fob signal and the alarm memory contain the same identifier codes, which are recorded when programming the key fobs. Each such identifier is unique and is embedded during production. Even if an attacker intercepts the radio signal, they will not succeed, since each time the signal will be new.
To make it easier for readers to understand the principle of operation of a system with a floating code and an individual key, let's explain this with a household example.
Let's imagine that the code key is a book. For example, "Dunno on the Moon". We need to transmit a coded signal in the form of a sequence of numbers from one source to another. Let's replace the numbers from 0 to 9 with the first ten letters of the Russian alphabet (from A to K, excluding Yo and Y). So, A is 1, B is 2, and so on. We transmit an identifier of four digits, for example, 2233, which in letter form looks like BBVV. We open the book and look for a word starting with the letter B. We find it on the tenth page, in the third line, and this word is BOLSHOY. We write down its coordinates: 010003005.
This is only the first letter of the code. For the second digit, we look for a word on another page and in another line, and so on. Having encoded the identifier, we transmit a sequence of numbers to another source. It, having the same book (key), decrypts the information in reverse order. If someone intercepts the data during transmission, they will only receive a set of unrelated numbers. Without the key (book), it is impossible to decrypt the message.
A logical question: "What if you try to steal the book and decipher the code?". Theoretically, this is possible, but if the book is kept in a safe with limited access, the task becomes extremely difficult.
In the case of alarms, everything is even more complicated. Each subsequent copy of the same model has its own unique key. For example, one set of key fobs uses the book "Dunno on the Moon", another uses "War and Peace", and a third uses something else. Even if criminals buy a similar system and crack the key, it will not fit your car.
The conclusion is obvious: the best protection against scanners and code grabbers is modern alarms with a dynamically floating code. They really leave almost no chance for technically savvy car thieves.
It would seem that the protection is one hundred percent, but there are nuances. The alarm protects well against interior thieves, but it cannot always prevent theft. Some kidnappers suppress the key fob signal with a special "white noise" generator, that is, they simply jam it. The owner thinks that the key fob battery has died, and the car remains without protection. Then everything depends on where the car is. It is opened with a lock pick and they get into the cabin. The most daring thieves may not even turn off the alarm: they simply break the glass and take everything valuable.
As for code grabbers, we tried to buy them on the Internet, but sellers required company details and explanations of the purposes of use. Prices for such devices range from $1000 to $4500. However, it is not so easy to buy them: you need your own service station or another company that may need code grabbers in emergency situations. You can also find homemade scanners on the network, but videos about their "miraculous capabilities" are greatly exaggerated. If you decide to buy an alarm, choose only models with a floating code. Otherwise, the money will be wasted.
In the next article, we will talk with a specialist in installing alarms, and also try to get a story from a car thief. Follow our publications!
