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International Journal of Computer Applications (0975 8887)
Volume 177 No. 37, February 2020
Smart Lock Systems: An Overview
Diamond Celestine Aluri
Dept. of Computer Science and Systems Engineering,
Andhra University College of Engineering for Women,
Visakhapatnam, Andhra Pradesh, India
Smart lock can be regarded as the modern successor of the
traditional lock. This paper provides an overview of different
smart lock technologies. The smart lock system being adopted
in many homes and other commercial buildings today is an
innovative approach that provides many user-friendly benefits
with its tolerable downsides.
Smart lock, mobile apps, sensors, Bluetooth, Home security,
Home automation
Technology today has made a greater influence on many
aspects of our life. The Home Automation System is a
computerized and automated network of electronic devices
fashioned to exhibit control over home appliances and to
efficiently monitor them [1]. One of the emerging real-time
application that has gained much light is the Home Security
System. The smart lock system is an emerging framework that
is gradually replacing the traditional locks due to its
convenience and affordable prices.
A smart lock is an electromechanical device that performs
locking/unlocking operations using wireless protocols. Wired
networks were previously replaced by wireless
communications as they tend to provide more flexibility and
extensibility with an easy installation [1]. The smart lock is
operated wirelessly by a cryptographic key on authentication
providing access only to the authorized personnel. With the
advancement of technology and research, more robust security
mechanisms are developed. Accessing the smart lock system
using a fingerprint biometric system provides for increased
levels of security. Some smart locks have added camera
functionality to enhance their security. The smart lock is
plausibly the most salient component of a smart connected
A smart lock can be used for either commercial (offices,
hotels, malls, etc.) or residential (i.e., Home security) security
purposes. It allows third-party entities to access the lock
utilizing a virtual key that is sent to the recipient smartphone
over Wi-Fi, mobile app, proximity sensors, BLE enabled
devices, etc. Integrating Wi-Fi into the smart lock can have
several benefits among which is all-time status OTA updates.
The number of smartphone users is rapidly increasing, and its
uses are tremendous. Usage of a smartphone or other gadgets
to monitor and control the security of domestic or commercial
buildings makes the task much easier. It is, however, possible
to easily misplace keys than to lose a phone hence, the smart
lock system uses this fact to its advantage. Moreover, to
ensure high-end security while using smartphones, the
standard AES encryption can be used which is hard to
penetrate [3].
Various versions of smart locks have been developed and the
need to improve security offers a wide area of research. In this
paper, few of the versions of smart locks are elaborated with
their salient features.
2.1 Electromechanical lock
For the functioning of a smart lock, like the traditional locks,
it requires a lock and a key. Here, the electromechanical lock
accomplishes locking and unlocking operations employing a
cryptographic key that receives instructions using a wireless
protocol. It is an electronically augmented deadbolt installed
onto any desired location (usually an exterior door) [2].
2.2 Cryptographic key
A cryptographic key is either a smartphone or a key fob which
authenticates to automatically open the door and is generated
by executing an encryption algorithm. The key required to
unlock is not necessarily a smartphone now. The technologies
have evolved to a larger extent which now implements the
locking and unlocking operations via BLE enabled devices,
sensors, and various other protocols such as ZigBee, and the
like, which are discussed in this paper.
3.1 Mobile/Web apps
The smart locks affixed provide access to its authorized users
through digital keys. The digital keys issued are highly
encrypted and can provide access through different levels
namely, owner, resident, recurring guest, and temporary guest
[2]. These smart locks once installed require the user to login
to the associated mobile/web application in order to be
authenticated. Security and privacy are regarded as a major
concern. The authenticated users can access the smart lock
through the application from anywhere with a strong internet
connection. The authorization process executes using a
wireless protocol and a cryptographic key. These applications
are designed in such a way that it provides for alerts to the
user’s mobile device when any intruder tries to unlock or
gains unauthorized access. The owner can grant or revoke
access any time to trusted ones via sharing the virtual keys
through standard messaging protocols (e-mail, SMS). The
owner is provided with access to view all the lock access logs
and monitor its entire functioning. The resident keys have all-
time access to the home/building whereas the recurring user
has scheduled access as set by the owner. The temporary
guest also has similar access in a short-term access window
Many locks support pairing up with devices through
Bluetooth connectivity (Ultraloq UL3, August 3rd Gen) but,
now to have a strong pairing and the longevity of the
connection throughout the building many favor robust Wi-Fi
connection as well (August Pro 3rd Gen with Connect Wi-Fi
International Journal of Computer Applications (0975 8887)
Volume 177 No. 37, February 2020
3.2 Sensors
There are several home automation devices either in existence
or are currently being developed that allow for automated
mechanisms to monitor and control devices that are a part of
the home security system. In this paper, the smart lock is the
major concern that plays a key role in ensuring high security
to the users from theft or other criminal activities that might
hamper their security or privacy. The idea of embedding
sensors into the smart lock ensures an effortless way to lock
or unlock your door. Sensors like PIR, optical sensor and such
are used to read and detect objects.
The most common motion sensor used in smart locks is the
PIR (Passive Infrared) sensor. The PIR sensor measures the
infrared light radiating from the objects with the help of
electronic semiconductors [1]. All warm-blooded animals
induce IR radiation. These sensors comprise a pyroelectric
film material that responds to the infrared radiation by
generating electricity which triggers the set burglar alarm.
They are an effective means for a home security system as
they also consume less energy and are almost long-lasting.
A PIR sensor can be combined with a microwave sensor to
operate in different areas of the spectrum. The microwave
sensor emits microwave pulses to detect the reflection off the
mobile objects. Thus, such dual technology motion sensors
are very less likely to trigger false alarms. Many recent
developments recommend combining video cameras with
advanced signal processing that are controlled by motion
Several optical sensors that are most commonly used for
contactless detection are incorporated in smart locks. An
optical sensor evaluates the physical quantity of light and
transforms it into a readable form for the integrated measuring
device based on the associated sensor. Biometric
authentication refers to the identification of humans by their
characteristics or traits [4]. While implementing biometric
authentication for the smart locks, it requires the user to enter
the finger through the optical sensor that generates a template
of finger images which are compared to match templates from
the library. Fingerprint verification involves generating
fingerprint templates that are stored as images or as biometric
algorithms. This makes it easier to match and verify
fingerprints against the pre-specified and stored fingerprints in
the libraries. This system offers increased levels of user
authentication to provide access only to authorized users.
3.3 Bluetooth
Bluetooth is considered as a wireless network solution in the
realm of home networking. Bluetooth provides for an
elementary, economical, and secure solution which has made
its use quite widespread in mobile devices. Bluetooth is a
short-range wireless technology standard that aims at the
simplified exchange of data among devices through short-
wavelength UHF radio waves in the network [5]. With the
help of the Bluetooth system, the user can transmit signals to
the door to lock or unlock with any BLE device that is
available (tablet, smartphone, etc.). This technology facilitates
the administrator or owner to send digital signals to other
trusted ones to provide access which requires NFC equipped
In general, the users are required to install the lock’s mobile
app on their smartphones/tablets to have an authenticated user
account to prevent unauthorized access and to monitor the
functioning of the security system. Once installed, the mobile
device is paired with the lock via a local wireless channel
(Bluetooth Low Energy). These locks depend on the user’s
mobile device which acts as an Internet Gateway which
transmits information between the server and the mobile
device in the BLE range of the lock. Once the devices are
paired, whenever in the BLE range the devices are connected,
and the user can utilize all the available functions to control
the lock. The BLE enabled devices can operate within a range
of 10m to 100m of distance at the speed of up to 3 Mbps
depending on the class of the Bluetooth devices. They operate
over a frequency band of 2.4GHz [6]. It also facilitates
sending e-keys over the mobile app and its ability to detect the
user’s presence is another feature that has increased its usage.
3.4 Wi-Fi
Wi-Fi is said to be the family of wireless networking
technologies that provide high-speed internet and network
connection. It uses radio waves to ensure an easy, secure and
quick data exchange between devices over a network. The
usage of smartphones has undergone a rapid increase and
various applications require a strong internet connection
which can be provided by having a robust Wi-Fi connection.
Smartphones are now also used as a tool to control smart
home technology that is growing at a very fast rate.
The smart lock system requires to be connected to a home
LAN connection to which the user is connected. The Local
Area Connection (LAN) which can be formed by a simple
router is said to be the most essential and key component of
the smart lock system that is built based on Wi-Fi security.
The smart lock system is designed such that it consists of a
central control system that performs functions such as reading
the commands, storing data, locking/unlocking operations,
and other functions that crucial to the system. A mobile
application provides the user with all controls to monitor the
locking system as he/she desires. It stores all the digital keys
and the user can also create and send temporary keys to guests
or any trusted ones [3]. This system has an easy installation
process and with its operation, by minimum complexity and
strong feasibility, it provides for better locking system
prospects [3].
Table 1. Summary of the properties of few smart locks
(source: “Smart Locks: Lessons for Securing Commodity
Internet of Things Devices”, by Grant Ho, et al.)
key fob
button in
mobile app;
Mobile app
button in
mobile app
or web
button in
mobile app;
International Journal of Computer Applications (0975 8887)
Volume 177 No. 37, February 2020
4.1 Teodoor
The Teodoor lock is a reliable Bluetooth technology lock that
uses the latest military-grade encryption technologies. With its
cryptographic co-processor that enables the usage of safer
encryption algorithms that reduce the processing time, it also
lowers the power consumption. It is powered by replaceable
lithium batteries. It also works on a hands-free mode where it
locks/unlocks the door on detecting its owner. The Teodoor
lock facilitates detailed scheduled access functions and also
provides an easy and quick way to provide access rights to the
trusted ones by the owner. [7]
Figure 1: Teodoor Smart Lock (source:
4.2 Kevo
The Kevo smart locks are manufactured by Kwikset which is
an American lock and lockset manufacturer owned by
Spectrum Brands Hardware and Home Improvement Group, a
Division of Spectrum Brands. The Kevo smart lock uses
multiple levels of military-grade encryption to provide
increased smart lock security. The dual-factor authentication
adds extra security to the smart lock system. In case of a lost
phone, one can long into their kevo account online to suspend
e-keys and disable their phones. Most Kevo locks link the
smartphone and the lock using Bluetooth. It allows creating
electronic keys that can be shared with the trusted ones.
Another important feature is the Kevo fob that can be used in
the absence of a smartphone. The Kevo family includes the
Kevo Contemporary lock that provides a touch-to-open
convenience, the Kevo traditional lock, the Kevo Convert lock
that has a smart lock conversion kit, Kevo plus that provides
for remote access, and the Kevo fob. [8]
Figure 2: Kevo smart locks from Kwikset (source:
4.3 August
August has launched its Wi-Fi smart lock which provides
remote access to lock/unlock doors, grant virtual keys to
trusted ones or use a voice assistant to control it. With its
built-in Wi-Fi, it requires no bridge to connect. The smart lock
system allows pairing with smartphones or other potential
devices to enable keyless access. It requires the owner to be
an authorized user on the August app which provides an
efficient interface to monitor and control the lock and to check
for the status and any updates.
The guest book function to keep track of all the recent access
data is an important feature embedded into it as it keeps the
owner informed about all the activities to provide an even
secure home in a smarter way. The smart lock system by
August (1st gen or 2nd gen, etc.) uses strong encryption
standards that include BLE encryption technologies and TLS
in mobile applications [9].
Figure 3: August Smart Lock (source:
The installation of smart locks to enhance the security of
homes or any commercial building is made very convenient
and easy. Also, the security standards make them a much
reliable substitute for conventional locks. This technology
implements an automatic locking/unlocking system that can
be activated by smartphones or biometric readers which
eliminates the dilemma of being locked out or misplaced leys.
The key feature of providing exclusive access to authorized
users enhances the security and these locks cannot be easily
tampered. The functionality to detect intruders or any person
and to record their activities in the set geographical range
present in many smart lock systems ensures a much reliable
and secure smart home. It serves as an ideal tool to ensure
security at commercial buildings and work environments as
this system allows only authorized personnel to have access
control to a specific area. Besides having an easy installation
process, it makes it easier to activate and access the lock as it
does not restrict it to smartphones; the advanced versions
consist of key fobs and other BLE devices that can access the
locks simultaneously. Despite having a biometric
identification or smartphone access to lock/unlock, many
locks now provide a keypad to create a pin or password that
identifies the authorized user.
The major drawback of smart locks is when the owner tries to
access the lock with a smartphone with a low battery. During
a low battery condition, the smartphone has many of its
features disabled and it may not be efficient enough to
International Journal of Computer Applications (0975 8887)
Volume 177 No. 37, February 2020
perform its locking/unlocking function as it might further
drain the battery. Also, during a blackout of the control unit or
any faulty condition the user is stranded as he/she cannot gain
access to the system. Like any software it is possible for
intruders to exploit its vulnerabilities and to tamper the
device; the manufacturers thus make constant efforts to
release regular updates that improve their encryption
standards in order to make it harder for unauthorized users to
penetrate and to increase the security of the system.
The smart lock system has gained great significance in the
global market today. Constant efforts are being made to
improve the standards of security and to ease the operation
and control over the smart home security system. This paper
outlines various features that are currently available in smart
locks. Considering the various versions discussed, it gives us
an ample understanding of how the smart lock system
enhances the security of home or workplace by providing
hassle-free access from anywhere.
[1] Jayant Dabhade, Amirush Javare, Tushar Gayal, Ankur
Shelar, Ankita Gupta 2017. Smart Door Lock System:
Improving Home Security using Bluetooth Technology”,
International Journal of Computer Applications (0975
8887) Vol. 160 (8), pp.19-22.
[2] Grant Ho, Derek Leung, Pratyush Mishra, Ashkan
Hosseini, Dawn Song, David Wagner 2016. “Smart
Locks: Lessons for Securing Commodity Internet of
Things Devices”, in ASIA CCS’16: Proceedings of the
11th ACM on Asia Conference on Computer and
Communications Security, pp. 461-472.
[3] Abdallah Kassem and Sami El Murr, Georges Jamous,
Elie Saad and Marybelle Geagea 2016. “A Smart Lock
System using Wi-Fi Security”, in 2016 3rd International
Conference on Advances in Computational Tools for
Engineering Applications (ACTEA), pp.222-225.
[4] Anu and Bhatia, D. 2014. “A smart door access system
using finger print biometric system”, Int. J. Medical
Engineering and Informatics, Vol. 6, No. 3, pp.274280.
[5] Stogu Pavel 2015. “Smart Lock System”,
[6] Lubhansh Kumar Bhute, Gagandeep Singh, Avinash
Singh, Vikram Kansary, Preetam Rao Kale, Shailendra
Singh 2017. “Automatic Door Locking System Using
Bluetooth Module”, International Journal for Research in
Applied Science & Engineering Technology (IJRASET),
Vol. 5 (V), pp.1128-1131.
[7] Martin K, Teodoor, your personal doorman Kickstarter,
accessed 26 June 2019,
[8] Spectrum Brands, Inc. n.d., Kwikset - Kevo, 2019
[9] August Home, designed in San Francisco, California,
2019, August Wi-Fi Smart Lock
... The error can be fixed in the middle of the project.5. Small projects can be implemented quickly, unlike large projects it is very difficult to estimate the time to develop it. ...
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Previously, for high security areas or in locker rooms for banks, traditional lock systems, passwords, etc., were employed. However, these systems were found to be not perfectly secure. After advancements in technology RFID cards were used. These cards however were not much useful for the user due to chances of getting lost, stolen and forgotten. The purpose of this study is to provide high security for such high end security applications. The aim of this study is to design a smart door access system using finger print module. The use of this device is to provide access to only authorised persons. Both hardware and software technology are used to design it. An emergency beep sound is provided to protect the system by giving alarm if any unauthorised person intrudes into the system. An indicator indicates for any emergency condition. Motors are used for locking and unlocking the door.
Conference Paper
We examine the security of home smart locks: cyber-physical devices that replace traditional door locks with deadbolts that can be electronically controlled by mobile devices or the lock manufacturer's remote servers. We present two categories of attacks against smart locks and analyze the security of five commercially-available locks with respect to these attacks. Our security analysis reveals that flaws in the design, implementation, and interaction models of existing locks can be exploited by several classes of adversaries, allowing them to learn private information about users and gain unauthorized home access. To guide future development of smart locks and similar Internet of Things devices, we propose several defenses that mitigate the attacks we present. One of these defenses is a novel approach to securely and usably communicate a user's intended actions to smart locks, which we prototype and evaluate. Ultimately, our work takes a first step towards illuminating security challenges in the system design and novel functionality introduced by emerging IoT systems.
Automatic Door Locking System Using Bluetooth Module
  • Gagandeep Lubhansh Kumar Bhute
  • Avinash Singh
  • Vikram Singh
  • Preetam Kansary
  • Shailendra Rao Kale
  • Singh
Lubhansh Kumar Bhute, Gagandeep Singh, Avinash Singh, Vikram Kansary, Preetam Rao Kale, Shailendra Singh 2017. "Automatic Door Locking System Using Bluetooth Module", International Journal for Research in Applied Science & Engineering Technology (IJRASET), Vol. 5 (V), pp.1128-1131.