Keyless entry into the car: what it is and how it works

Many years ago, there was a grandiose idea to completely abandon locks that could be opened with ordinary metal keys. More specifically, automotive engineers had the idea of ​​creating keyless access to a car and eliminating the need to use a regular key altogether about fifty years ago.

How it works

The driver touches the door handle. The electronic control unit (ECU) for keyless entry receives a signal from a sensor located in it. After this, the control unit searches for the key, which should be no further than one and a half meters from the door. If all conditions are met, two-way data exchange begins between the key and the car. The process takes place in two stages: the ECU sends a signal to the key, and it responds.

After the first acquaintance, the ECU must make sure that the key is genuine. To do this, he resends the encoded signal, and the key must send “feedback”. If identification is successful, the ECU communicates with the comfort unit, which gives the command to open the locks. The system is very reliable in terms of signal encoding - the dialogue between the key and the car lasts such a short time that attackers do not have time to intercept and process the signal.

Types of systems

In general, the difference between keyless systems lies largely in the form rather than in the content itself. All intelligent keyless entry systems are based on a similar principle. But the smart keys themselves can be implemented and executed in different ways.

Initially, the developers were not sure that the electronics would completely ensure that the engine was turned off after the driver used keyless entry. There were also some doubts regarding the reliability of the equipment. In order for the driver to accurately turn off the engine or have the opportunity to disable security systems, manufacturers initially equipped them with additional folding keys. They were used for reinsurance. This was typical for cars that were produced until about the beginning of the 2000s. Then they gave up the keys.

As for the implementation of modern smart keys, they are mainly special cards or a key fob.

In the case of a key fob, there is usually the additional ability to remotely start the engine. When getting into the car, the key is inserted into a special groove, and thereby the engine starts and the locking systems are turned off.

What does it consist of?

An electronic key can be made in the form of a classic key with buttons, a key fob or a smart card. The functionality depends on the brand and level of equipment of the car. Inside the key is a microcircuit that encodes and decodes the signal. To do this, it uses a floating code algorithm, which is considered one of the most reliable today. The antenna is used to receive and transmit encoded signals.

Electronic key

Electronic key

Sensor in door handles

Sensor in door handles

Replacement battery

If the battery in the smart key runs low, you must use a backup method to unlock and start the car. Opening is accomplished by an emergency (fully mechanical) key blade, usually hidden in the smart key. On many vehicles, emergency starting is achieved through the use of an inductive clutch. The user must either insert the key into the slot or hold it near a special area on the cabin where an induction coil is hidden, which transfers energy to the corresponding coil in the dead key fob via inductive charging.

The slots have proven problematic as they can fail and the key becomes locked and cannot be removed. Another problem with the slot is that it cannot compensate for battery drain below a certain operating threshold. Most smart key batteries are temperature sensitive, causing the fob to stop working, completely, or not work in the same day.

Handyman

Will open the trunk

. You can open not only the doors, but also the trunk without contact. On some cars, you don’t even need to touch the button to do this, just move your foot under the bumper: motion sensors will record the command, the automation will unlock the lock and activate the electric drive.

Typically, two capacitive proximity sensors are used, located in the lower and upper parts of the bumper and determining the command position of the leg. This function only works when the engine is not running to prevent false alarms when parking.

Raise the windows and close the sunroof

. On many models with keyless entry, windows and hatches automatically close when arming. To do this, you need to touch the sensor responsible for closing and do not release it until the windows and sunroof close.

Starting the engine without a key.

A prerequisite for starting the engine is that the key is inside the passenger compartment. When you press the start button, codes are exchanged using exactly the same protocol as when opening doors.

If you do not first depress the brake or clutch pedal (depending on the gearbox), only the ignition will turn on. To turn off the engine, just press the button again.

What are the disadvantages of keyless entry into the car?

To do this, a car thief will need an assistant and a special device - a repeater. The device costs a lot of money, but a successful theft pays for everything.

During the “operation” the assistant is located next to the owner of the car (key or immobilizer). It establishes a digital connection with the device. His accomplice near the car presses the door open button. The signal is processed in the repeater and sent to the assistant, who, maintaining communication with the key, sends the signal back. This scheme works on almost any car.

To make it clearer, let's look at a specific example. You drove up to the store, parked your favorite car in the parking lot and went shopping. Naturally, your car has an SBDA installed.

A certain entity with a repeater is sent after you, which constantly sends a signal from your key to the car. There is a second suspicious subject with a second repeater near the car. He receives his friend's signal and redirects it to the car. SBDA, thinking that the true owner is nearby, opens the doors to the car thief.

Why does not it work

• The key battery or vehicle battery is discharged.
• It is not recommended to store the key near a mobile phone: interference from its operation can lead to malfunctions of the keyless entry system and push-button start of the engine.
• Strong electromagnetic interference, for example near a television center, can reduce the range of reliable operation of the system.
• Door handle sensors don't last forever. Water, reagents and dirt corrode wires, and sometimes corrosion destroys sensors. The treatment is simple and inexpensive: you need to restore the connection and properly insulate it.
• On some vehicles, during repairs, the connectors for the high-frequency speaker and the keyless entry antenna may be mixed up. In this case, the system stops working. It is easy to calculate such castling. If the speaker is silent, you need to remove the door panel and connect the wires correctly.

Keyless access: main system vulnerabilities

Principle of operation

Now it will be interesting to understand in more detail how the keyless entry system for a car works, and what the operating principle of the keyless entry system is based on. This will make it clear how effective and safe the node is. Objectively, keyless entry has its strengths and weaknesses, which will be discussed later.

Motorists using keyless entry must first learn about the features of its operation before buying a car with such a system or installing it separately on their own vehicle in order to enjoy the benefits of the keyless entry system.

The interesting thing here is that the operating principle of keyless entry into a car is quite simple, but at the same time its technical implementation is very complex. Despite the name, the key is still used here. Only it can be executed in different variations, but not in the usual sense of the word.

The key contains an electronic unit. It is this that allows you to open the car with keyless entry. The manufacturer always describes in detail how exactly you can open the car. Although the work scheme of all companies is almost identical.

When the car owner approaches the vehicle at a distance that corresponds to the range of the signal, the electronics reads the code of the smart key, removing the lock and protection. This opens the car's locks. When the driver gets into the cabin, he will only need to press the Start button for the engine to start.

Start button to start the engine

By pressing the engine start button, the signal goes to the control unit and is transmitted to the smart key using antennas. It signals what is inside the car, followed by information to the central locking and alarm system. Having transmitted the signal, the anti-theft systems are turned off, and the driver can start the engine and go about his business.

After leaving the car, when a certain distance is reached between the car and the key in your pocket, the electronics lose contact with the electronic unit, thereby automatically locking all doors and opening the electrical circuits.

In a nutshell, the car receives a signal from the owner’s key and only opens when it is read. If the signal disappears, the system blocks access to the vehicle.

From this we can conclude that the system works on a fairly simple principle, and there is nothing complicated here. But still, the developers had to spend more than a dozen years to get a modern version of the Smart Key.

The problem of delays in the implementation of the database is due to the fact that initially the developers could not provide for secure access

After all, it was important that the system in the car recognizes only the key of the immediate car owner, and not any other one passing by. Otherwise, the car could easily be opened with another similar key, simply by approaching the required distance

The first tests clearly showed what serious vulnerabilities there are in equipment designed to obtain keyless access. There was nothing difficult about intercepting the signal and projecting it onto the car from another key. To do this, it was enough to have a portable receiver and radio transmitter.

One of the proposed solutions was the introduction of cryptographic protection. But in this case, the code would be uniform, which also did not guarantee reliable protection against theft and hacking.

With the advent of digital technologies, the problem of the first SDB prototypes was solved. It was with the help of digital developments that complex coding was created. Thus, the developers were able to effectively establish interaction between the car and the electronic Smart key, using the so-called floating code.

The essence of the innovation was that when a signal is received, an arbitrary code is generated from a huge number of options and combinations of numbers. Yes, attackers can intercept it, but they still won’t be able to use this code to open the car, since at the next stage of opening a completely different code combination is created. Moreover, codes are generated instantly. Since there are an incredible number of code options, it will not be possible to crack it simply by selecting numbers.