Recently, there has been a notable surge in the development of generative models dedicated to synthesizing 3D scenes. In these research works, Neural Radiance Fields(NeRF) is one of the most popular AI approaches due to its outstanding performance with relatively smaller model size and fast training/ rendering time. Owing to its popularity, it is important to investigate the NeRF model security concern. If it is widely used for different applications with some fatal security issues would cause some serious problems. Meanwhile, as for AI security and model robustness research, an emerging adversarial Bit Flip Attack (BFA) is demonstrated to be able to greatly reduce AI model accuracy by flipping several bits out of millions of weight parameters stored in the computer's main memory. Such malicious fault injection attack brings emerging model robustness concern for the widely used NeRF-based 3D modeling. This master thesis is targeting to study the NeRF model robustness against the adversarial bit flip attack. Based on the research works the fact can be discovered that the NeRF model is highly vulnerable to BFA, where the rendered image quality will have great degradation with only several bit flips in the model parameters.

Over the past few years, the Internet of Things (IoT) has become an essential element of daily life. At the core of IoT are the densely deployed heterogeneous IoT sensors, such as RFID tags, cameras, temperature sensors, pressure sensors. These sensors work collectively to sense and capture intricate details of the surroundings, enabling the provision of highly detailed and comprehensive information. This fine-grained information encompasses a wide range of critical parameters that contribute to intelligent decision-making processes. Therefore, the security and privacy of heterogeneous IoT systems are indispensable. The heterogeneous nature of IoT systems poses a number of security and privacy challenges, including device security and privacy, data security and privacy, communication security, and AI and machine learning security. This dissertation delves into specific research issues related to device, communication, and data security, addressing them comprehensively. By focusing on these critical aspects, this work aims to enhance the security and privacy of heterogeneous IoT systems, contributing to their reliable and trustworthy operation. Specifically, Chapter 1 introduces the challenges and existing solutions in heterogeneous IoT systems. Chapter 2 presents SmartRFID, a novel UHF RFID authentication system to promote commodity crypto-less UHF RFID tags for security-sensitive applications. Chapter 3 presents WearRF-CLA, a novel CLA scheme built upon increasingly popular wrist wearables and UHF RFID systems. Chapter 4 presents the design and evaluation of PhyAuth, a PHY message authentication framework against packet-inject attacks in ZigBee networks. Chapter 5 presents NeighborWatch, a novel image-forgery detection framework for multi-cameras system with OFoV. Chapter 6 discusses the future work.

The Internet-of-Things (IoT) paradigm is reshaping the ways to interact with the physical space. Many emerging IoT applications need to acquire, process, gain insights from, and act upon the massive amount of data continuously produced by ubiquitous IoT sensors. It is nevertheless technically challenging and economically prohibitive for each IoT application to deploy and maintain a dedicated large-scale sensor network over distributed wide geographic areas. Built upon the Sensing-as-a-Service paradigm, cloud-sensing service providers are emerging to provide heterogeneous sensing data to various IoT applications with a shared sensing substrate. Cyber threats are among the biggest obstacles against the faster development of cloud-sensing services. This dissertation presents novel solutions to achieve trustworthy IoT sensing-as-a-service. Chapter 1 introduces the cloud-sensing system architecture and the outline of this dissertation. Chapter 2 presents MagAuth, a secure and usable two-factor authentication scheme that explores commercial off-the-shelf wrist wearables with magnetic strap bands to enhance the security and usability of password-based authentication for touchscreen IoT devices. Chapter 3 presents SmartMagnet, a novel scheme that combines smartphones and cheap magnets to achieve proximity-based access control for IoT devices. Chapter 4 proposes SpecKriging, a new spatial-interpolation technique based on graphic neural networks for secure cooperative spectrum sensing which is an important application of cloud-sensing systems. Chapter 5 proposes a trustworthy multi-transmitter localization scheme based on SpecKriging. Chapter 6 discusses the future work.

The security of Internet-of-Things (IoT) is essential for its widespread adoption. The recent advancement in Artificial Intelligence (AI) brings both challenges and opportunities to IoT security. On the one hand, AI enables better security designs. On the other hand, AI-based advanced attacks are more threatening than traditional ones. This dissertation aims to study the dual effects of AI on IoT security, specifically IoT device security and IoT communication security. Particularly, this dissertation investigates three important topics: 1) security of acoustic mobile authentication, 2) Deep Learning (DL)-guided jamming attacks on cross-technology IoT networks, and 3) DL-powered scalable group-key establishment for large IoT networks. Chapter 2 presents a thorough study on the security of acoustic mobile authentication. In particular, this chapter proposes two mobile authentication schemes identifying the user's mobile device with its linear and nonlinear acoustic fingerprints, respectively. Both schemes adopt the Data Mining (DM) techniques to improve their identification accuracy. This chapter identifies a novel fingerprint-emulation attack and proposes the dynamic challenge and response method as an effective defense. A comprehensive comparison between two schemes in terms of security, usability, and deployment is presented at the end of this chapter, which suggests their respective suitable application scenarios. Chapter 3 identifies a novel DL-guided predictive jamming attack named DeepJam. DeepJam targets at cross-technology IoT networks and explores Deep Reinforcement Learning (DRL) to predict the victim's transmissions that are not subject to the Cross-Technology Interference (CTI). This chapter also proposes two effective countermeasures against DeepJam for resource capable and resource constrained IoT networks, respectively. Chapter 4 proposes a drone-aided DL-powered scalable group-key generation scheme, named DroneKey, for large-scale IoT networks. DroneKey is a physical-layer key generation scheme. In particular, DroneKey actively induces correlated changes to the wireless signals received by a group of devices and explores DL techniques to extract a common key from them. DroneKey significantly outperforms existing solutions in terms of the scalability and key-generation rate.