Physical layer key generation has attracted considerable attention in the past decade since it provides an alternative solution for the key establishment in wireless networks using channel reciprocity. In this paper we explore the possibility of physical layer key generation for emerging Low Power Wide Area Networks (LPWAN) such as LoRa (Long Range). However, due to the lower transmission rates of LPWANs compared to Wi-Fi and Zigbee, the channel reciprocity is relatively low, which makes timely key generation challenging. To address this problem, we propose a novel information-theoretic key generation scheme that can operate at all data rate settings, featuring a model-based key generation method. Furthermore, we derive an optimal window size to calculate the parameters of the channel model based on a random waypoint model to balance the channel reciprocity and entropy. Extensive evaluations on a campus testbed show that our method can achieve up to 13.8 bps key generation rate. Compared to state-of-the-art methods, the proposed method improves key generation rate by 3x to 5x. We also analyzed the security of the proposed approach and demonstrated it to be resilient to eavesdropping attacks.

In recent years, we have witnessed the rapid development of the long range (LoRa) technology, together with extensive studies trying to understand its performance in various application settings. In contrast to measurements performed in large outdoor areas, a limited number of attempts have been made to understand the characterization and performance of the LoRa technology in indoor environments. In this article, we present a comprehensive study of the LoRa technology in multifloor buildings. Specifically, we investigate the large-scale fading characteristic, temporal fading characteristic, coverage, and energy consumption of the LoRa technology in four different types of buildings. Moreover, we find that the energy consumption using different parameter settings can vary up to 145 times. These results indicate the importance of parameter selection and enabling the LoRa adaptive data rate feature in energy-limited applications. We hope the results in this article can help both academia and industry understand the performance of the LoRa technology in multifloor buildings to facilitate developing practical indoor applications.

There is an increasing interest in Internet of Things (IoT) enabled smart buildings over the past decades. However, the development of smart buildings is impeded by the high installation/maintenance cost and the difficulty of large-scale evaluation in the wild. In this paper, we report the design, implementation, and deployment of an emergency light-based smart building solution. The key advantage of the system is that it is built on the top of the existing facilities in the building (i.e., emergency light). As a case study, we have implemented and deployed our system in nine production smart buildings of different types including residential, commercial office, and warehouse of multiple level building complexes. Using real data from four typical buildings, we show the proposed system can achieve >97% average packet delivery rate. Evaluation results also demonstrate the stability and robustness of the system to environmental changes. The results of this paper provide practical insights to facilitate the development of smart building systems.

The capability to securely (re)program embedded devices over-the-air is a fundamental functionality for the emerging Internet of Things (IoT). Current approaches work efficiently by exploiting the homogeneity within sensing devices, where all nodes require the update and participate in the process. Due to the heterogeneity of IoT deployments, where the type of devices and program images vary, existing solutions suffer from severe performance degradation. We address this shortcoming with our system SEDA, which leverages a secure multicast approach. SEDA outperforms existing systems since the program image is securely delivered and processed on targeted nodes only, hence reducing the overhead for not involved nodes. In order to enable the multicast approach, we introduce an asymmetric broadcast encryption primitive, which we have optimized towards constrained nodes to reduce the communication/computation overhead as compared to existing approaches. With an extensive experimental study on a public testbed in several practical settings, we show SEDA's efficient performance compared to state-of-the-art approaches. Finally, our theoretical security analysis shows SEDA's security against identified adversary models.

Formal security analysis has proven to be a useful tool for tracking modifications in communication protocols in an automated manner, where full security analysis of revisions requires minimum efforts. In this paper, we formally analysed prominent IoT protocols and uncovered many critical challenges in practical IoT settings. We address these challenges by using formal symbolic modelling of such protocols under various adversaries and security goals. Furthermore, this paper extends formal analysis to cryptographic Denial-of-Service (DoS) attacks and demonstrates that a vast majority of IoT protocols are vulnerable to such resource exhaustion attacks. We present a cryptographic DoS attack countermeasure that can be generally used in many IoT protocols. Our study of prominent IoT protocols such as CoAP and MQTT shows the benefits of our approach.

The Internet of Things (IoT) is an emerging paradigm, where the ubiquitous devices can form the networks and connect to Internet. Security and management of devices remain open challenges for the IoT. We adopt the management framework of industry consortium THREAD, where a group of devices cooperating to accomplish the same task (called policy) are administrated by a designated device called commissioner and together they form a policy group. All these policy groups are further managed by a centralized server. In this hierarchical network structure, the secure distribution of the policy information, access control, and group key from the centralized server to commissioner and its peers become challenging given the pervasive, complex and heterogeneous properties of devices. To solve this, we propose protocols/mechanisms along with a variant of Broadcast Encryption called Secure Identity-Based Broadcast Encryption (SIBBE) and demonstrate the feasibility for secure distribution of information to the IoT devices from centralized server. Most of the related work is based on the Attribute-based Encryption (ABE) for IoT devices, which has scalability issues with the number of attributes. Our experimental and simulation evaluations show that our scheme outperforms the existing schemes in terms of scalability, latency, and communication overhead.

The capability to securely manage embedded devices is arguably a fundamental functionality for the emerging Internet of Things (IoT). Current Wireless Sensor Networks (WSNs) approaches are not applicable directly for IoT deployments due to new challenges from emerging IoT applications. We propose to address this shortcoming and enhance the process while providing a sufficient level of security. This work proposes to design, implement and evaluate an efficient and secure software update/manage architecture for the IoT. We plan to conduct an extensive experimental study on a public testbed to evaluate the design tradeoff and quantify the performance of our architecture.

Current Wireless Sensor Networks (WSNs) approaches do not provide an efficient and secure code dissemination function due to emerging issues of IoT applications. In this work, we adopt a multicast approach instead of the existing end-to-end or epidemic approaches. In order to enable the multicast approach, we propose an efficient/robust group key distribution scheme. We will evaluate and quantify the performance of our prototype implementation in a public testbed, while emulating several practical IoT settings, and show our security measures against known attack models.