# OpticalTrust: A Sensor-to-Blockchain Framework Using Free-Space Optical Communication
## 2 Related Work
### Sensor Network and Blockchain  
In recent years, the synergy of blockchain technology with sensor networks has garnered significant attention due to its capabilities to enhance data security, integrity and transparency in numerous applications. Recent research has directed its attention on harnessing the intrinsic characteristics of blockchain technology to enhance data management in sensor networks. In [14], the authors propose a novel approach to enhancing data security in wireless sensor networks (WSNs) by integrating blockchain technology with data transfer protocols. The system employs small-area WSNs, each with a primary \"mobile database\" node utilizing embedded microcontrollers, to create a robust IoT-based network architecture. By adapting blockchain principles to sensor data records and implementing private cloud-end functionality, the research aims to significantly improve data reliability and tamper-resistance in WSN structures. A decentralized system is proposed in [15] to enhance the security, privacy, reliability and autonomy of IoT ecosystems. By integrating blockchain technology and cryptographic tools, the purpose of this study is to protect data integrity and availability. [PERSON] [16] proposed an encryption and trust evaluation model based on blockchain technology for wireless sensor networks. The model authenticates aggregator nodes and sensor nodes using public and private blockchains, respectively, and employs trust value computation to identify and eliminate malicious nodes. To secure the sensor node data, RSA encryption is applied. There are some studies focused on WSN protocols using blockchain technology. A systematic review of the integration of blockchain technology (BCT) and the Internet of Things (IoT) is presented in [17] to address security and privacy challenges. The study examines the basic principles, architectures, protocols, and consensus algorithms of both BCT and IoT, as well as the challenges of their integration. It analyzes various approaches to leveraging blockchain's security features in IoT ecosystems, categorizing applications based on characteristics such as development level, blockchain type, and consensus algorithm. In [18], the authors propose a novel blockchain-based authentication protocol for WSNs to address security vulnerabilities in existing protocols, particularly ID spoofing attacks. The research leverages blockchain's cryptographic security features to enhance data integrity and source verification in WSNs. The protocol incorporates a private blockchain network connecting sensor nodes, cluster nodes, and a base station. The integration approach of blockchain technology and IoT faces a number of challenges, which include the storage capacity and scalability issue, resource constraints of IoT devices, transaction rate limitations, and legal complexities. These challenges stem from the vast amounts of data generated by IoT devices, their limited computational power and energy resources, and the need for high-speed, real-time data processing in many IoT applications. FSOs could potentially address some of these challenges by offering high-bandwidth, energy-efficient, and secure communication links.