A Novel Keyless Entry System Using Visible Light Communication

International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.5, No.5, October 2014
A NOVEL KEYLESS ENTRY SYSTEM USING VISIBLE
LIGHT COMMUNICATION
Kuniyoshi Okuda, Hideaki Shirai, Tomoo Nakamura and Wataru Uemura
Department of Electronics and Informatics, Ryukoku University, Shiga, Japan
ABSTRACT
A major conventional car key is the mechanical key. When users inserted the key into a cylinder mechanical
key and turn, users can unlock. The mechanical key may be able to be worn away for physical contact. And it
may be impossible to use. Further the mechanical key may be damaged or destroyed by mischief. So a keyless
entry system has been developed. The keyless entry system locks and unlocks using the infrared ray and radio
waves communication. The keyless entry system does not require physical contacts. Therefore, the
possibilities of damage due to mischief and be worn away are fell. However, the transmission ranges of
infrared ray and radio waves communication are not clear. Submitting data might be tapped to the malicious
people. If the information is tapped, then you have theft of the car and the risk of car break.
We propose a keyless entry system using visible light communication in order to solve this problem. Visible
light communication transmits signal using blinking light. Thus the transmission range is clear. The user can
transmit the information only to the aimed place. Therefore, the usability is improved. We measure the
durations of "take out the remote control", "put the aim" and "takes to unlock key" in order to evaluate the
usability in the experiment. We also compared with the infrared ray communication and examined the
superiority. Usability is improved in the experimental results, and usability is better than conventional
keyless entry system.
KEYWORDS
Keyless entry system, Infrared ray communication, Visible light communication
1. INTRODUCTION
Recently many car manufacturers are adopting the keyless entry system. A keyless entry system
unlocks doors without the key inserted into the keyhole. In the traditional mechanical key (Figure
1), keyholes and keys are worn away. Therefore the mechanical key will be difficult to unlock or
lock. And people with malicious might to unlock forcibly or destroy the keyhole by malicious
mischief. The keyless entry system solves these problems.
There are some types of authentication methods. In the case of two-way communication, there are
the zero-knowledge proof and challenge-response. In the challenge response, at first the transmitter
sends an authentication request. After the receiver gets it, the receiver sends back a random number
sequence. It is called a challenge. The transmitter receives the challenge, and combined with the
password and challenge. It is called response. The transmitter sends the response. In the same way,
the receiver makes response. It receives transmitter's challenge and checks.
The Zero-knowledge proof is a proof method to check the remainder of the quotient. The receiver
DOI : 10.5121/ijasuc.2014.5501 1

sends the divisor to the transmitter. The transmitter divides by the received divisor password. The
transmitter calculates the remainder, and sends it to the receiver. In the same way, the receiver
calculates the remainder. It receives transmitter's remainder and check. The transmitter and the
receiver repeat these steps several times.
2
Figure 1: mechanical key and keyless entry module
2. SOME PROBLEMS OF THE CONVENTIONAL KEY
The mechanical key is used long time on many occasions even now. There are several types of
mechanical key. Most major keys are a cylinder type. A cylinder type has some cylinders in the
keyhole. The cylinders of different lengths move up and down. When the user inserts into the key
hole, the lock cylinder are arranged in a row. The key is unlocked when the cylinders are in a line.
Mechanical keys have some weak points. One is that it is damaged or destroyed the keyhole [1-4].
When the key is broken there is a possibility of theft.
Therefore the keyless entry system does not require a mechanical lock and has become widespread.
The keyless entry system locks and unlocks using the remote control. The keyless entry system uses
infrared ray and radio waves communication for unlocking. The system does not require physical
contact. Therefore, the possibility of wear of the keyhole and the key is less. The possibility of
mischief and theft is also low. Users can unlock using the mechanical key in an emergency.
However humans can not know the propagation area of the infrared ray and radio waves, because
humans are not able to view the infrared ray and radio waves. Therefore we cannot know a reach
emitted signal from the remote control. However, people with malicious may intercept the contents
of communication using the listening device [5].
A smart entry system has been developed now. The smart entry system is an extension to keyless
entry system. The smart entry system transmits and receives using radio waves. This system does
not require the manipulation of the remote controller to lock and unlock. Users with a remote
control can unlock by approaching the car. And users with the remote control can start the engine
without the mechanical key, because the remote control communicates with the car.

However the starting of the engine and unlocking can be even a person with malicious intent, when
it is in the vicinity of the car remote control of regular. Also, if the user forgets the key, it is
impossible to start the engine on the go.
For preventing eavesdropping, the transmitter sends data to only a specific location. However the
communication areas of infrared ray and radio waves are unclear, because we cannot see the
infrared ray and radio waves. That is, it is impossible for the users to understand the transmission
range of the transmitted data. It is a benefit to a people with malicious. Therefore, with the use of
visible light communication [6-8], it is possible to lower the potential to provide the password to the
people with malicious. Visible light communication is different from the conventional
communication method. Visible light communication sends information by blinking light. We can
understand intuitively the communication range that is characteristic of visible light
communication. Its transmission range is lit by light. The user can understand intuitively
transmission range. We can use the lighting infrastructure as transmitters of visible light
communication. Recently, The LED is used as a lighting equipment. The LED is long life and high
brightness, and further it is expected success.
3
Figure 2: Visible light communication
3. A NOVEL KEYLESS ENTRY SYSTEM USING VISIBLE LIGHT
COMMUNICATION
We propose a keyless entry system using visible light communication. The conventional keyless
entry system uses radio waves or infrared rays. Therefore the transmission range is unknown. Our
proposed system uses visible light communication for keyless entry system. Therefore the
transmission range is clear. We show the proposed system in Figure 3.

4
Figure 3: keyless entry system using visible light communication
The remote control includes the LED. The remote control sends the password by using visible light
communication. The car has a receiver.
The transmission range of infrared ray and radio waves communication used by conventional
keyless entry system is not clear. However our proposed system is different. We can see the
transmission range of visible light communication. Thus the user does not send the information to
unnecessary place. Therefore information is less likely to be tapping. The user easily can transmit
information in an aimed location. It improves the usability.
Our proposed system uses bidirectional communication. An outward path is visible light
communication and a return path is infrared ray communication. Our proposed system
authenticates a bidirectional communication. We assume that the authentication method is the
zero-knowledge proof or challenge-response. Infrared ray communication might be tapping.
However, important information is not sent in return path. And modulation system is required
to be constant transmission energy by the code.
4. EXPERIMENT
We show fabricated transmitter and receiver in Figure 4 and 5.
Figure 4: the transmitter

Figure 5: the receiver
The transmitter can perform infrared
replacing the LED. We use the PPM
Brightness is not changed by the data in PPM.
ray
communication or visible light communication programmatically, because the receiver has
elements of visible light and infrar
PPM (pulse
position modulation) as a modulation scheme [9
the PPM.
We evaluate the usability of a proposed keyless entry system.
convenience. We measure N/E
represents the ratio of the operating time of the designer and the operating time of the general user.
That is the operating time of the designer N/
time of the general user. It is judged to have a high usability. We
entry system using infrared ray communication
time to take out the remote control,
General users and designers measure them.
We show the results of the experiment
2
1.5
1
0.5
0
Measurement time
take out the remote control
ray communication or visible light communication by
(pulse position modulation) to the modulation scheme.
The receiver can perform infrared
infrared ray for receiver module. And we use the
9-10]. We prevent flicker by using
The usability means ease of use and
(novice expert ratio method) ratio in the experiment. N/
E ratio
rating E ratio is low, there is no difference in the operation
compare the conventional keyless
and proposed system. The measurement items
time to put the aim and the time it takes to unlock the key.
In addition, we calculate the N / E ratio of at that time.
in the Figure 6 and 7.
time it takes to unlock the key
put the aim
take out the remote control
put the aim time it takes to unlock the key
Figure 6: measurement time
5
ference easurement are
e

6
N/E ratio
put the aim time it takes to unlock
N/E(VLC) N/E(IR)
Figure 7: N/E ratio
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
take out the remote
control
the key
Remote control parts are common except for the LED. Therefore, there was no difference in time to
time other than "time it takes to unlock the key". We think that the cause is clear communication
range. Human can understand intuitively transmission range of visible light communication.
Therefore, if the user can aim to the wrong place, they can to correct aim immediately. However,
infrared ray communication is different. We cannot see the transmission range of the infrared ray
communication. Then, the user cannot understand intuitively transmission range. Thus correcting
the aim is not easy for the user. Long time, designers are working with a remote control. So
designers are familiar with the operation. Therefore, they understand to some extent sighting.
General users are unfamiliar with the operation. Therefore, the result is different.
5. CONCLUSION
We proposed a keyless entry system using visible light communication in this paper. The
conventional keyless entry system uses an infrared ray or radio waves. The user sends information
to unnecessary place, because we cannot see the transmission area of infrared ray and radio waves
communication. Therefore, it is possible that people with malice eavesdropping information. So we
attempt to solve the problem by using visible light communication. Visible light communication is
a communication that is visible to the eye. One of characteristic of visible light communication is to
visible transmission range. Therefore, the user does not send the information to unnecessary place.
In addition, the transmission range of visible light communication is clear. Therefore, users can
operate intuitively. So we propose a keyless entry system using visible light communication. Our
proposal can be put on the aim intuitively as compared with the keyless entry system of
conventional. Therefore, usability is good.
We have measured N/E ratio to evaluate the usability in experiments. N/E ratio is a comparison of
the operation time of the general user and operation time of the designer. If this value is low,
usability is good. The measurement item is "take out the remote control", "put the aim" and "takes
to unlock key". We compared by infrared ray communication with visible light communication the
three items.
The results of the experiment, took time to unlock up to the general user compared to the designer
in the infrared ray communication. There was no much difference between them in visible light

communication. We think that the cause is easy to aim. The transmission range of infrared ray
communication is not clear. However, visible light communication is different. The users can
correct aim easily, because they can understand intuition transmission range.
From the experimental results, we show that our usability of proposed system is better than
conventional keyless entry system.
7
REFERENCES
[1] Eli Biham, Orr Dunkelman, “How to Steal Cars -A Practical Attack on KeeLoq”, pp.3 (2007)
[2] Nicolas T. Courtois, Gregory V. Bard, and David Wagner, “Algebraic and Slide Attacks on
KeeLoq, (2007)
[3] Thomas Eisenbarth, Timo Kasper, Amir Moradi, Christof Paar, Mahmoud Salmasizadeh, and
Mohammad T. Manzuri Shalmani hysical, “Cryptanalysis of KeeLoq Code Hopping
Applications”, (May 8, 2008)
[4] Nathan Keller, Orr Dunkelman, Eli Biham, and Bart Preneel, “A Practical Attack on KeeLoq”,
pp.4,5(2008)
[5] Saleh Almowuena, “AN EFFICIENT KEY AGREEMENT SCHEME FOR WIRELESS
SENSOR NETWORKS USING THIRD PARTIES”, IJASUC Vol.4, No.4, 2013
[6] S.Haruyama,"Visible light communication", Journal of IEICE, 94(12), D, pp. 1055-1059,
2011
[7] Rajan Sagotra, "Visible Light Communication", International Journal of Computer Trends and
Technology (IJCTT) volume4 Issue4, pp. 906-910, 2013
[8] Dominic C. O'Brien, "Visible Light Communications: challenges and possibilities", PIMRC
2008. IEEE 19th International Symposium on Personal, Indoor and Mobile Radio
Communications, pp.15-18, 2008
[9] T. Saito, "A Study for flicker on Visible Light Communication", Technical Report of IEICE
CS, vol. 106, No. 450, pp. 31-35, 2007.
[10] I.Shouichi, "Reduction of Flicker by Coding and Modulation for Visible-Light
Communication" Technical Report of IEICE OCS, vol. 108, No. 39, pp. 1-4, 2008.

8
AUTHORS
Kuniyoshi Okuda (b.1986) is a student of Ryukoku University in Japan. After
studying Electronics and Informatics at Ryukoku University, he completed his
Master of Engineering at Osaka City University. Now he is a doctor course student at
Ryukoku University.
Hideaki Shirai received B.E, M.E. and D.E. degrees from Ryukoku University, in
2010 and 2012, respectively.
Tomoo Nakamura was born in 1948, and received B.E, M.E. and D.E. degrees
from Kyoto University, in 1970, 1972, and 1988. He is a professor of Ryukoku
University in Shiga, Japan.
Wataru Uemura was born in 1977, and received B.E, M.E. and D.E. degrees
from Osaka City University, in 2000, 2002, and 2005. He is an associate
professor of the Department of Electronics and Informatics, Faculty of
Engineering Science, Ryukoku University in Shiga, Japan. He is a member
of IEEE, RoboCup and others.

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