A smart key is an

electronic Electronic may refer to: *Electronics, the science of how to control electric energy in semiconductor * ''Electronics'' (magazine), a defunct American trade journal *Electronic storage, the storage of data using an electronic device *Electronic co ...

access and authorization system that is available either as standard equipment, or as an option in several car designs. It was first developed by Siemens in 1995 and introduced by

Mercedes-Benz Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquarter ...

under the name "Keyless-Go" in 1998 on the W220 S-Class, after the design patent was filed by Daimler-Benz on May 17, 1997.

How it works

The smart key allows the driver to keep the

key fob A keychain (also key fob or keyring) is a small ring or chain of metal to which several keys can be attached. The length of a keychain allows an item to be used more easily than if connected directly to a keyring. Some keychains allow one or b ...

pocketed when unlocking, locking and starting the vehicle. The key is identified via one of several

antennas In radio engineering, an antenna or aerial is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. In transmission, a radio transmitter supplies a ...

in the car's bodywork and a radio pulse generator in the key housing. Depending on the system, the vehicle is automatically unlocked when a button or sensor on the door handle or trunk release is pressed. Vehicles with a smart-key system have a mechanical backup, usually in the form of a spare key blade supplied with the vehicle. Some manufacturers hide the backup lock behind a cover for styling. Vehicles with a smart-key system can disengage the immobilizer and activate the ignition without inserting a key in the ignition, provided the driver has the key inside the car. On most vehicles, this is done by pressing a starter button or twisting an ignition switch. When leaving a vehicle that is equipped with a smart-key system, the vehicle is locked by either pressing a button on a door handle, touching a capacitive area on a door handle, or simply walking away from the vehicle. The method of locking varies across models. Some vehicles automatically adjust settings based on the smart key used to unlock the car. User preferences such as seat positions, steering wheel position, exterior mirror settings, climate control (e.g. temperature) settings, and stereo presets are popular adjustments. Some models, such as the

Ford Escape The Ford Escape is a compact crossover SUV sold by Ford since 2000 over four generations. The first generation was jointly developed with Mazda which also created the Mazda Tribute and Mercury Mariner as the twin model. Second generations of t ...

, even have settings to prevent the vehicle from exceeding a maximum speed if it has been started with a certain key.

Nomenclature

Manufacturers use keyless authorization systems under different names: * Acura: Keyless Access System *

Alfa Romeo Alfa Romeo Automobiles S.p.A. () is an Italian luxury car manufacturer and a subsidiary of Stellantis. The company was founded on 24 June 1910, in Milan, Italy. "Alfa" is an acronym of its founding name, "Anonima Lombarda Fabbrica Automobili." ...

: Passive Entry *

Audi Audi AG () is a German automotive manufacturer of luxury vehicles headquartered in Ingolstadt, Bavaria, Germany. As a subsidiary of its parent company, the Volkswagen Group, Audi produces vehicles in nine production facilities worldwide. The o ...

: Advanced Key *

Aston Martin Aston Martin Lagonda Global Holdings PLC is an English manufacturer of luxury sports cars and grand tourers. Its predecessor was founded in 1913 by Lionel Martin and Robert Bamford. Steered from 1947 by David Brown, it became associated ...

: Keyless Entry and Push Button Start * BMW: Comfort Access or Display Key *

Bugatti Automobiles Ettore Bugatti was a German then French manufacturer of high-performance automobiles. The company was founded in 1909 in the then- German city of Molsheim, Alsace, by the Italian-born industrial designer Ettore Bugatti. The ca ...

: Keyless Entry Remote *

Cadillac The Cadillac Motor Car Division () is a division of the American automobile manufacturer General Motors (GM) that designs and builds luxury vehicles. Its major markets are the United States, Canada, and China. Cadillac models are distributed ...

: Adaptive Remote Start & Keyless Access *

Citroën Citroën () is a French automobile brand. The "Automobiles Citroën" manufacturing company was founded in March 1919 by André Citroën. Citroën is owned by Stellantis since 2021 and previously was part of the PSA Group after Peugeot acquired ...

: Keyless Entry and Start System * FIAT-Chrysler: Keyless Enter-N-Go *

Ford Ford commonly refers to: * Ford Motor Company, an automobile manufacturer founded by Henry Ford * Ford (crossing), a shallow crossing on a river Ford may also refer to: Ford Motor Company * Henry Ford, founder of the Ford Motor Company * Ford F ...

: Intelligent Access with push-button start * General Motors: Passive Entry Passive Start (PEPS) *

Honda is a Japanese public multinational conglomerate manufacturer of automobiles, motorcycles, and power equipment, headquartered in Minato, Tokyo, Japan. Honda has been the world's largest motorcycle manufacturer since 1959, reaching a producti ...

: Smart Entry System *

Hyundai Hyundai is a South Korean industrial conglomerate ("chaebol"), which was restructured into the following groups: * Hyundai Group, parts of the former conglomerate which have not been divested ** Hyundai Mobis, Korean car parts company ** Hyundai As ...

: Proximity Key and smart entry key *

Infiniti is the luxury vehicle division of the Japanese automaker Nissan. Infiniti officially started selling vehicles on November 8, 1989, in North America. The marketing network for Infiniti-branded vehicles included dealers in over 50 countries in ...

: Infiniti Intelligent Key with Push-button Ignition * Isuzu: Genius Entry * Jaguar Cars: Smart Key System *

Jeep Jeep is an American automobile marque, now owned by multi-national corporation Stellantis. Jeep has been part of Chrysler since 1987, when Chrysler acquired the Jeep brand, along with remaining assets, from its previous owner American Motors ...

: Keyless Enter-N-Go *

Kia Motors Kia Corporation, commonly known as Kia (, ; formerly known as Kyungsung Precision Industry and Kia Motors Corporation), is a South Korean multinational automobile manufacturer headquartered in Seoul, South Korea. It is South Korea's second la ...

: Smart Key System *

Land Rover Land Rover is a British brand of predominantly four-wheel drive, off-road capable vehicles, owned by multinational car manufacturer Jaguar Land Rover (JLR), since 2008 a subsidiary of India's Tata Motors. JLR currently builds Land Rove ...

: Keyless Entry *

Lexus is the luxury vehicle division of the Japanese automaker Toyota. The Lexus brand is marketed in more than 90 countries and territories worldwide and is Japan's largest-selling make of premium cars. It has ranked among the 10 largest Japanese ...

: Smart Access System * Lincoln: Intelligent Access System *

Maserati Maserati S.p.A. () is an Italian luxury vehicle manufacturer. Established on 1 December 1914, in Bologna, Italy, the company's headquarters are now in Modena, and its emblem is a trident. The company has been owned by Stellantis since 2021. ...

: Passive Entry System *

Mazda , commonly referred to as simply Mazda, is a Japanese Multinational corporation, multinational Automotive industry, automotive manufacturer headquartered in Fuchū, Hiroshima (town), Fuchū, Hiroshima Prefecture, Hiroshima, Japan. In 2015, M ...

: Advanced Keyless Entry & Start System *

: Keyless Go integrated into SmartKeys *

Mini The Mini is a small, two-door, four-seat car, developed as ADO15, and produced by the British Motor Corporation (BMC) and its successors, from 1959 through 2000. Minus a brief hiatus, original Minis were built for four decades and sold during ...

: Comfort Access *

Mitsubishi Motors is a Japanese multinational automobile manufacturer headquartered in Minato, Tokyo, Japan.Nissan: Nissan Intelligent Key *

Peugeot Peugeot (, , ) is a French brand of automobiles owned by Stellantis. The family business that preceded the current Peugeot companies was founded in 1810, with a steel foundry that soon started making hand tools and kitchen equipment, and then ...

: PEUGEOT Open & Go * Porsche: Porsche Entry & Drive System * Proton: Passive Keyless Entry *

Renault Groupe Renault ( , , , also known as the Renault Group in English; legally Renault S.A.) is a French multinational automobile manufacturer established in 1899. The company produces a range of cars and vans, and in the past has manufacture ...

: Renault Hands Free Keycard *

Saab Saab or SAAB may refer to: Brands and enterprises * Saab Group, a Swedish aerospace and defence company, formerly known as SAAB, and later as Saab AB ** Datasaab, a former computer company, started as spin off from Saab AB * Saab Automobile, a fo ...

: Keyless Passive Entry * SsangYong Motor: Smart Key System * Subaru: Keyless Smart Entry With Push-Button Start or Keyless Access with Push-Button Start *

Suzuki is a Japan, Japanese multinational corporation headquartered in Minami-ku, Hamamatsu, Japan. Suzuki manufactures automobiles, motorcycles, All-terrain vehicle, all-terrain vehicles (ATVs), outboard motor, outboard marine engines, wheelchairs ...

: SmartPass Keyless entry & starting system *

Toyota is a Japanese multinational automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on . Toyota is one of the largest automobile manufacturers in the world, producing about 10 ...

: Smart Key System *

Vauxhall Vauxhall ( ) is a district in South West London, part of the London Borough of Lambeth, England. Vauxhall was part of Surrey until 1889 when the County of London was created. Named after a medieval manor, "Fox Hall", it became well known for ...

Opel Opel Automobile GmbH (), usually shortened to Opel, is a German automobile manufacturer which has been a subsidiary of Stellantis since 16 January 2021. It was owned by the American automaker General Motors from 1929 until 2017 and the PSA ...

: Keyless Open & Start *

Volkswagen Volkswagen (),English: , . abbreviated as VW (), is a German motor vehicle manufacturer headquartered in Wolfsburg, Lower Saxony, Germany. Founded in 1937 by the German Labour Front under the Nazi Party and revived into a global brand post ...

: Keyless Entry & Keyless Start or KESSY *

Volvo The Volvo Group ( sv, Volvokoncernen; legally Aktiebolaget Volvo, shortened to AB Volvo, stylized as VOLVO) is a Swedish multinational manufacturing corporation headquartered in Gothenburg. While its core activity is the production, distributio ...

: Personal Car Communicator "PCC" and Keyless Drive or Keyless Drive *

Mahindra & Mahindra Mahindra & Mahindra Limited (M&M) is an Indian Multinational corporation, multinational Automotive industry, automotive manufacturing corporation headquartered in Mumbai. It was established in 1945 as Mahindra & Mohammed and later renamed as Ma ...

: Smart Key Module

Insurance standard

In 2005, the UK motor insurance research expert Thatcham introduced a standard for keyless entry, requiring the device to be inoperable at a distance of more than 10 cm from the vehicle. In an independent test, the

Nissan Micra The Nissan Micra, also known as the , is a supermini car ( B-segment) that has been produced by the Japanese automobile manufacturer Nissan since 1982. The Nissan Micra replaced the Japanese-market Nissan Cherry. It was exclusive to Nissan J ...

's system was found to be the most secure, while certain BMW and Mercedes keys failed, being theoretically capable of allowing cars to be driven away while their owners were refueling. Despite these security vulnerabilities, auto theft rates have decreased 7 percent between 2009 and 2010, and the National Insurance Crime Bureau credits smart keys for this decrease.

SmartKeys

SmartKeys were developed by Siemens in the mid-1990s and introduced by

in 1997 to replace the infrared security system introduced in 1989. Daimler-Benz filed the first patents for SmartKey on February 28, 1997, in German patent offices, with multifunction switchblade key variants following on May 17, 1997. The device entailed a plastic key to be used in place of the traditional metal key. Electronics that control locking systems and the ignitions made it possible to replace the traditional key with a sophisticated computerized "Key". It is considered a step up from remote keyless entry. The SmartKey adopts the remote control buttons from keyless entry, and incorporates them into the SmartKey fob. Once inside a Mercedes-Benz vehicle, the SmartKey fob, unlike keyless entry fobs, is placed in the ignition slot where a starter computer verifies the rolling code. Verified in milliseconds, it can then be turned as a traditional key to start the engine. The device was designed with the cooperation of Siemens Automotive and Huf exclusively for Mercedes-Benz, but many luxury manufacturers have implemented similar technology based on the same idea. In addition to the SmartKey, Mercedes-Benz now integrates as an option Keyless Go; this feature allows the driver to keep the SmartKey in their pocket, yet giving them the ability to open the doors, trunk as well as starting the car without ever removing it from their pocket. The SmartKey's electronics are embedded in a hollow, triangular piece of plastic, wide at the top, narrow at the bottom, squared-off at the tip with a half-inch-long insert piece. The side of the SmartKey also hides a traditional Mercedes-Benz key that can be pulled out from a release at the top. The metal key is used for valet purposes such as locking the

glove compartment A glove compartment or glove box is a compartment built into the dashboard of an automobile, located over the front-seat passenger's footwell, and often used for miscellaneous storage. The name derives from the original purpose of the compar ...

and/or trunk before the SmartKey is turned over to a parking attendant. Once locked manually, the trunk cannot be opened with the SmartKey or interior buttons. The key fob utilizes a radio-frequency transponder to communicate with the door locks, but it uses infrared to communicate with the engine immobilizer system. The original SmartKeys had a limited frequency and could have only been used in line-of-sight for safety purposes. The driver can also point the smart key at the front driver side door while pushing and holding the unlock button on the SmartKey and the windows and the sunroof will open in order to ventilate the cabin. Similarly, if the same procedure is completed while holding the lock button, the windows and sunroof will close. In cars equipped with the Active Ventilated Seats, the summer opening feature will activate seat ventilation in addition to opening the windows and sunroof.

Display Key

Display Key is a type of smart key developed by BMW that includes a small LCD color touchscreen on it. It performs the standard functions that a key fob would normally do such as locking, unlocking & keyless start, but because of the screen the user can also perform a number of the features from BMW's app. One of which includes commanding the car to self park from the key if your car has self parking capability. The key is currently available for the

3 Series The BMW 3 Series is a line of compact executive cars manufactured by the German automaker BMW since May 1975. It is the successor to the 02 Series and has been produced in seven generations. The first generation of the 3 Series was only avail ...

, 4 Series,

5 Series The BMW 5 Series is an executive car manufactured and marketed by BMW since 1972, succeeding the New Class Sedans, and currently in its seventh generation. The 5 Series was initially available as a sedan, with a wagon/estate body style (market ...

, 6 Series, 7 Ser

ies The initialism IES may refer to: Government organizations * Indian Economic Service * Indian Education Service, in British India * Institute for Environment and Sustainability of the European Commission * Institute of Education Sciences of the U.S ...

, 8 Series, X3, X4, X5, X6, and X7. The key is rechargeable and will last about 3 weeks. It can be charged via a micro USB port on the side or wirelessly on the center console.

Keyless Go

Keyless Go (also: Keyless Entry / Go; Passive Entry / Go) is Mercedes' term for an automotive technology which allows a driver to lock and unlock a vehicle without using the corresponding SmartKey buttons. Once a driver enters a vehicle with an equipped Keyless Go SmartKey or Keyless Go wallet-size card, they have the ability to start and stop the engine, without inserting the SmartKey. A

transponder In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a flight trans ...

built within the SmartKey allows the vehicle to identify a driver. An additional safety feature is integrated into the vehicle, making it impossible to lock a SmartKey with Keyless Go inside a vehicle. KeylessEntryGoCircuitUnits

The system works by having a series of LF (

low frequency Low frequency (LF) is the ITU designation for radio frequencies (RF) in the range of 30–300 kHz. Since its wavelengths range from 10–1 km, respectively, it is also known as the kilometre band or kilometre wave. LF radio waves e ...

125 kHz) transmitting antennas both inside and outside the vehicle. The external antennas are located in the door handles. When the vehicle is triggered, either by pulling the handle or touching the handle, an LF signal is transmitted from the antennas to the key. The key becomes activated if it is sufficiently close and it transmits its ID back to the vehicle via RF (

Radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the uppe ...

>300 MHz) to a receiver located in the vehicle. If the key has the correct ID, the PASE module unlocks the vehicle. The hardware blocks of a Keyless Entry / Go

Electronic control unit An electronic control unit (ECU), also known as an electronic control module (ECM), is an embedded system in automotive electronics that controls one or more of the electrical systems or subsystems in a car or other motor vehicle. Modern vehic ...

ECU are based on its functionality: * transmitting low-frequency LF signals via the 125 kHz power amplifier block * receiving radio frequency RF signals (> 300 MHz) from the built-in ISM receiver block * encrypting and decrypting all relevant data signals (security) * communicating relevant interface signals with other electronic control units *

microcontroller A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs ( processor cores) along with memory and programma ...

Inside Outside detection

The smart key determines if it is inside or outside the vehicle by measuring the strength of the LF fields. In order to start the vehicle, the smart key must be inside the vehicle.

Security requirements

It is important that the vehicle can't be started when the user and therefore the smart key is outside the vehicle. This is especially important at fueling stations where the user is very close to the vehicle. The internal LF field is allowed to overshoot by a maximum of 10 cm to help minimise this risk. Maximum overshoot is usually found on the side windows where there is very little attenuation of the signal. RelayStationAttack

A second scenario exists under the name "relay station attack" (RSA). The RSA is based on the idea of reducing the long physical distance between the car and the regular car owner's SmartKey. Two relay stations will be needed for this: The first relay station is located nearby the car and the second is close to the SmartKey. So on first view, the Keyless Entry / Go ECU and the SmartKey could communicate together. A third person at the car could pull the door handle and the door would open. However, in every Keyless Entry / Go system provisions exist to avoid a successful two-way communication via RSA. Some of the most known are: * measuring

group delay In signal processing, group delay and phase delay are delay times experienced by a signal's various frequency components when the signal passes through a system that is linear time-invariant (LTI), such as a microphone, coaxial cable, amplifier, ...

time to detect illegal high values * measuring third-order intercept point to detect illegal

intermodulation Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency com ...

products * measuring

field strength In physics, field strength means the '' magnitude'' of a vector-valued field (e.g., in volts per meter, V/m, for an electric field ''E''). For example, an electromagnetic field results in both electric field strength and magnetic field strength. ...

of the electric field * measuring the response time of 125 kHz

LC circuit An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can ...

* using a more complex

modulation In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the '' carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informat ...

(i.e.

quadrature amplitude modulation Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message sig ...

) which can't be demodulated and modulated by a simple relay station Furthermore, Keyless Entry / Go communicates with other ''Control Units'' within the same vehicle. Depending on the electric car architecture, the following are some ''Control Systems'' that can be enabled or disabled: * ESCL Electric Steering Column Lock * EIS Electronic Ignition Switch * Central door locking system *

Immobiliser An immobiliser or immobilizer is an electronic security device fitted to a motor vehicle that prevents the engine from being started unless the correct key (''transponder'' or '' smart key'') is present. This prevents the vehicle from being " ...

Engine Control Unit An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by ...

(Motor management system) * BCU Body control unit Another possibility is using a motion sensor within the key fob.

Internal LF field dead spots

Dead spots are a result of the maximum overshoot requirement from above. The power delivered to the internal LF antennas has to be tuned to provide the best performance i.e. minimum dead spots and maximum average overshoot. Dead spots are usually near the extremities of the vehicle e.g. the rear parcel shelf.

Battery Backup

If the battery in the smart key becomes depleted, it is necessary for there to be a backup method of opening and starting the vehicle. Opening is achieved by an emergency (fully mechanical) key blade usually hidden in the smart key. On many cars emergency starting is achieved by use of an

inductive coupling In electrical engineering, two conductors are said to be inductively coupled or magnetically coupled when they are configured in a way such that change in current through one wire induces a voltage across the ends of the other wire through el ...

. The user either has to put the key in a slot or hold it near a special area on the cockpit, where there is an inductive coil hidden behind which transfers energy to a matching coil in the dead key fob using

inductive charging Inductive charging (also known as wireless charging or cordless charging) is a type of wireless power transfer. It uses electromagnetic induction to provide electricity to portable devices. Inductive charging is also used in vehicles, power too ...

. Slots have proven to be problematic, as they can go wrong and the key becomes locked in and cannot be removed. Another problem with the slot is it can't compensate for a fob battery below certain operating threshold. Most smart key batteries are temperature sensitive causing the fob to become intermittent, fully functional, or inoperative all in the same day.

Special Cases

A Keyless Entry / Go system should be able to detect and handle most of the following cases: * SmartKey Transponder was forgotten in the rear trunk * More than one SmartKey is present inside the car * SmartKey getting lost during the drive * Smartkey battery low (Limp-Home)

History

The system is based on a technology invented by Siemens VDO called PASE: Passive Start and Entry System. It operates in the

ISM band The ISM radio bands are portions of the radio spectrum reserved internationally for industrial, scientific and medical (ISM) purposes, excluding applications in telecommunications. Examples of applications for the use of radio frequency (RF) en ...

of radio frequencies. Keyless Entry / Go was introduced first by

in the S-Class car series in 1998.

Outlook

Today a Keyless Entry / Go system is a state-of-the art technology and still has a lot of potential to optimise. Here are some general trends of the advance (AD) and series development (SD): * SD: reduction of used LF antennas in low-cost compact cars (results in a loss of detection quality) * AD: using electric field antennas instead of magnetic field antennas (cost reduction) * AD: using microwave frequencies (radar) instead of an LF and RF combination (more comfort) * AD:

Biometric Biometrics are body measurements and calculations related to human characteristics. Biometric authentication (or realistic authentication) is used in computer science as a form of identification and access control. It is also used to identify ...

authentication Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicat ...

would identify the user and not the SmartKey transponder

Effectiveness

A test by

ADAC ADAC, officially the Allgemeiner Deutscher Automobil-Club (), is Europe's largest motoring association. ADAC is the largest club (Verein) in Germany with around 21 million members. It would be more aptly described today as an individual m ...

revealed that 20 car models with Keyless Go could be entered and driven away without the key. In 2014, 6,000 cars (about 17 per day) were stolen using keyless entry in

London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...

References

External links

Relay Attacks on Passive Keyless Entry and Start Systems in Modern CarsSecurity Flaws of Remote {{DEFAULTSORT:Electronic Key Smart devices
Automotive technology tradenames">Smart devices">Security Flaws of Remote {{DEFAULTSORT:Electronic Key Smart devices
Automotive technology tradenames Radio electronics Vehicle security systems