DOT-C: A smartphone unlock scheme based on dot-dot connection in IoT-enabled smart cities

For developing a future smart city environment, the Internet of Things (IoT) is a foundational technology to support smart city functionalities, e.g., connecting physical devices and sensors with a data analysis module. Smartphone is one of the typical IoT devices that has been widely used in an IoT-enabled smart city, hence it is very important to protect the device from unauthorized access. Currently, one common solution is to design an unlock scheme to safeguard the smartphone and its stored data. In this work, motivated by this trend, we propose DOT-C, a phone unlock scheme based on dot-dot connection, aiming to facilitate the usage in smart cities (e.g., convenience). Our scheme is built upon the Android Unlock Pattern (with 9 dots) and requires an individual to connect two dots two times. In the evaluation, we perform a user study with 90 participants and compare the scheme performance with two similar schemes. The obtained results indicate that our scheme can provide suitable security and usability in a practical environment. Copyright © 2025 The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.