# Exploiting Blockchain Technology for Enhancing Digital Twins' Security and Transparency
## 3 Proposed Approach  
To address the challenges related to the digital twin's security system and avoiding potential information leakage, we proceeded by defining the key objectives to satisfy. The first is undoubtedly tied to the implementation of an access control system; this measure safeguards the information exchanged with the digital twins and ensures that data are handled solely by authorized entities, thereby preventing their misuse for unauthorized purposes. The first proposed measure to ensure the security of exchanged data is based on the integration of blockchain accounts assigned to all authorized entities in the system. Each authorized entity requires a corresponding blockchain address granting as proof of his authenticity. The validation system of communication sources relies on the introduction of a private backbone blockchain. This blockchain records the entities interacting with the digital twin, enhancing the overall security of the communication process. Due to the requirements of our system, no monetary transaction is performed over this backbone structure, and any transaction fee is totally excluded from the equation. Regarding the integrity of data within the security system, a validation component is integrated to ensure that received data correspond to the data sent by the originating entity. This measure is essential to avoid discrepancies and to guarantee the reliability and authenticity of the exchanged data. To achieve this objective, the system incorporates a data validation mechanism within the smart-contract subsystem, complemented by a middleware component integrated into the communication infrastructure. By leveraging the autonomy of the introduced stub component within the digital twin subsystem, off-chain transaction signing is employed, thereby maintaining the locality of the operation and avoiding unnecessary data transfers. The integrated middleware component of the system manages the logical operations serving as a foundation for the administrative control and management of the digital environment and its full description is represented in Figure 1.  
To further enhance the security of data transmitted to the blockchain component, a hashing mechanism is employed. The hash of the data is computed and transmitted alongside the signed transaction. In a hypothetical communication, the digital twin only accepts pre-validated information on the blockchain through the middleware component. Additionally, data transmission from the digital twin occurs only after undergoing an additional layer of validation. This approach ensures that the logical layer retains only the \"fingerprint\" of the shared information, enriching the overall data locality while minimizing the stored volume of data on the blockchain. In order to guarantee a deterministic and programmatic approach to the digital twin's information and the underlying blockchain, a smart-contract-based subsystem is adopted to  
Figure 1: Diagram of the proposed architecture for the communication between the system’s components and the underlying blockchain. manage the logic governing the system's components. Furthermore, to allow an incremental upgradability of the proposed solution, the EIP-1967 design pattern is adopted over the system logic through the implementation of an UUPS proxy. The long-term usability of the system is strictly related to those characteristics, as they are essential for ensuring the solution's adaptability to evolving security requirements. Those factors play a crucial role in the system's future development and ensure a sustained operational efficiency. In addition to the specific security measures previously outlined, it is essential that the proposed system incorporate robust administrative functionalities. These capabilities enable continuous monitoring and dynamic modification of communication flows within the digital environment. This characteristic is crucial for detecting and diagnosing potential security vulnerabilities by allowing proper interventions in order to address them.