# Integrating the IoT and Blockchain Technology for the Next Generation of Mining Inspection Systems
## 3 Proposed System Architecture  
We propose an architecture that integrates mobile devices, IoT sensors, and blockchain technology. The proposed architecture considers low-cost IoT sensing devices as direct actors on a blockchain network to guarantee a root of trust for the sensed data [25]. Furthermore, the integrity, auditability, and traceability of the sensed data are maintained and enforced by the blockchain network [28]. Here, we use blockchain technology as a decentralized trusted repository of information for several unknown and untrusted stakeholders, a proven use-case for blockchain [29]. Furthermore, we rely on existing blockchain implementations and protocols, as the type of consensus and the size of existing blockchains networks offer a more secure platform for developing new types of decentralized applications [30]. Due to practical restrictions, the proposed architecture has two main limitations. First, we only focus on measurements in the inspection process, as natural language processing for the observations is beyond the scope of this work. Second, even if the system considers several unknown stakeholders, we consider the OEM of tools and inspectors as trusted entities, and we focus on extending this trust to the other stakeholders in the system in a decentralized way. As shown in Figure 1, we consider an asset (e.g., truck, excavator) as the entry point of the information flow that ends with the production of an inspection report. The inspectedasset is of interest to several actors (e.g., OEM of assets and tools, asset owners, users, on-field inspectors, authorities) that interact with the four main components of the architecture: the cloud module, mobile app, connected tool, and the blockchain module. The cloud module supports the inspection business process (e.g., assets, inspections points, measurements, observations). It also holds the algorithms for evaluating safety-related risks and providing the inspection result. The mobile app benefits from portable devices (i.e., smartphones, tablets) and provides an interface to the onsite inspector to collect onsite measurements and observations. The mobile app automatically uploads the collected information to the cloud module when an Internet connection is available, minimizing the time overhead and possible errors due to manually writing the information. If no connection is available, the app can easily store the information of several inspections. Our architecture considers measuring tools that precisely measure several physical parameters (e.g., dimensions, noise, heat, light) needed during on-field inspections. These devices are called connected tool and include new generation measuring instruments or legacy devices retrofitted with low-cost IoT platforms. The onsite inspector uses the connected tool that directly interacts with the mobile app using near-field communication capabilities, simplifying the process and reducing human intervention. The last component is the blockchain module that gathers all the smart contracts representing assets, tools, inspections results, and certifications, providing a transparent record, auditable by all stakeholders. For blockchain operations, and aligned with current literature [26], the actors and devices in our systems are identified by their unique combination of public/private keys. More complex identity schemes are possible with blockchain, even realizing completely decentralized public key infrastructures [18]. However, this research topic is beyond the scope of this paper. This blockchain identity makes several inspection actions accountable to a particular actor (e.g., inspector, operator). Likewise, the IoT device also has a blockchain identity in our architecture and generates digitally signed transactions. The use of cryptography at the root of the architecture addresses some of the current security challenges in IoT applications [31] and guarantees that information generated by the device reaches the blockchain unaltered.