International Journal of Electrical and Computer Engineering (IJECE) Vol. 11, No. 4, August 2021, pp. 3267~3274 ISSN: 2088-8708, DOI: 10.11591/ijece.v11i4.pp3267-3274  3267 Journal homepage: http://ijece.iaescore.com Residential access control system using QR code and the IoT Pak Satanasaowapak, Witawat Kawseewai, Suchada Promlee, Anuwat Vilamat Department of Computer Engineering, Rajabhat Maha Sarakham University, Thailand Article Info ABSTRACT Article history: Received Aug 31, 2020 Revised Dec 23, 2020 Accepted Jan 13, 2021 This paper presents a residential access control system (RACs) using QR codes and the internet of things (IoT) to improve security and help house owners. The contribution of this paper is that it proposes two mechanisms in the authentication phase and the verification phase, respectively, to enhance residential access control. The main idea is using cryptography between smartphones and access control devices. The cryptography compares secret codes on the key server via the internet. The RACs can notify a user of the residential access status through the LINE application and show the statuses of devices through the network platform for the internet of everything (NETPIE) in real-time. We compare this system’s performance with that of the current access control methods in terms of security and access speed. The results show that this system has more security and has an access speed of 5.63 seconds. Moreover, this system is safer and more flexible than the comparative methods and suitable for contactless authentication. Keywords: Access control Authentication Cryptography Internet of things QR code This is an open access article under the CC BY-SA license. Corresponding Author: Pak Satanasaowapak Department of Computer Engineering Rajabhat Maha Sarakham University 80 Nakornsawan Road, Talad, Muang District, Maha Sarakham, 44000, Thailand Email: pak.satanasaowapak@gmail.com 1. INTRODUCTION Currently, residential safety is considered to be a priority by people. Most people use keys or key cards to access their residences. These things are what they have to carry with them at all times. However, if the keys or key cards are cloned, the residence can be accessed by an intruder. The common problems found in using keys to access residences are having to carry many keys, forgetting keys, losing keys, or even carrying too many items to the point that a person cannot use a key with their hand. Currently, many places do not require a key to access them, including convenience stores, airport entrances, and shopping malls. These doors or gates are designed to facilitate their users, and they are usually installed in public buildings. Moreover, some doors and gates are used by many users. These include office entrances, dormitory entrances, apartment and condominium entrances. These doors may require identification that does not use a key, such as a key card, a fingerprint scan, or a password. Even though these types of doors do not increase the number of keys for the users, the users still have to carry another object that causes the same problem as carrying a key. The fingerprint scan may be inconvenient if the user has to hold many things. Moreover, if a guest arrives at a residence before the house owners do, the guest has to wait until the owner arrives. This can be time-consuming, and the guest may not want to wait. Therefore, this research aims to solve the problem of using a key to access residences, buildings, or other places so that users will not need to carry additional objects or use biological information for authentication. Hence, users will be able to create keys for those who have been granted access. Internet of things (IoT) technology has begun to play more roles in people’s daily lives, as seen in the popularity of IoT equipment. Besides, smartphones have become indispensable for many people since