# Policy-Based Smart Contracts Management for IoT Privacy Preservation
## 3 Proposed Method: Policy-Based Smart Contract Management for IoT Privacy Preservation
### Privacy Analysis  
The proposed model enhances the privacy within IoT environment from several perspectives:  
1. **Control of the different stakeholders participating in the transaction. ** Privacy in private blockchain networks is particularly advantageous for transactions that require restricted access. Only authorized users can interact with the network, ensuring that sensitive data remain confidential [43]. The immutability of blockchain records prevents unauthorized tampering, making it ideal for storing sensitive information. Moreover, all participants in a transaction are fully informed of the preconditions and rules, ensuring transparency and accountability. 2. **Control of Service Level Agreement (SLA) before joining the blockchain network. ** Hyperledger Fabric allows the creation of endorsement policies, which specify which organizations must verify user transactions before they are considered valid. These policies help enforce Service Level Agreements (SLAs) between users and the blockchain network, as well as any other parties involved in the services provided. Our proposed model enables the user to easily adhere to the SLA requirementsthrough the policies managing the smart contracts. Therefore, the user could control the content, frequency, security, and automation of smart contracts. 3. **Enforcement of governance rules through smart contracts. ** Our proposed model provides the ability to define two levels of governance rules: * _User level._ Using policies that manage smart contracts, users can control their smart contracts and data shared with the blockchain network, and also the communication type with the blockchain network. * _Blockchain level._ Endorsement policies enable the identification of the parties responsible for handling user transactions. Hyperledger Fabric uses _Raft_ to manage the consensus between peers based on predefined policies upon their creation or when joining the blockchain network. Therefore, we provide both users and service providers the opportunity to control their assets, which enhances the trust between them. 4. **Enforcement of a private channel. ** With Hyperledger Fabric, transactions need to be verified by reputable networks of organizations, which reflects the real world accurately. Hyperledger Fabric's privacy protection enables the organization's authenticity on the blockchain, which is ensured by the digital certificate management service. The multichannel design divides the information into several channels and the necessity for privacy data isolation across various entities within the same channel is further satisfied by privacy data gathering. _Configxtgen_ CLI utility for generating channel configuration consists of a secret layer of communication between specific organizations, which is hidden from other network participants. Again, the adoption of Hyperledger technology enables the creation of private channels between the user and the specified peer and ensures that data are only accessed and viewed by the participating parties. Thus, we keep the user-sensitive data private and users are notified if any infringement is detected, since any illegal modification will be detected once the hash values are altered. 5. **Easy adherence to forensics requirements in an investigation case. ** Any digital record requires to prove its authenticity, privacy, non-hearsay nature, and comprehensiveness in order to be admissible in the court of law [44; 45; 46]. Using the private blockchain, any block is authentic (since the integrity and authentication of the stockholders are ensured through the hash mechanism and the MSP feature, respectively), private (since all privacy and access policies are defined in the SLA before the establishment of the blockchain network), comprehensive (since all records are saved and stored in the main ledger, so we can track the history of any transaction and establish complete and comprehensive data), and are not hearsay (since, by definition, any data generated by the digital device in normal routine are not hearsay).