# TrustShare: Secure and Trusted Blockchain Framework for Threat Intelligence Sharing
## 2 Background
### Private Blockchain
In contrast to conventional blockchain approaches, its operational phases adhere to the \"execute-order-validate\" pattern, a strategic departure that enhances adaptability and effectiveness, aligning with trustworthy threat intelligence sharing in this context. This ensures transactional processes supported by consensus and fault-tolerant algorithms [20]. Administrative duties in blockchain include setting up consensus protocols and replacing resource-intensive algorithms like proof of work or proof of stake with more efficient alternatives, such as Paxos, RAFT, or BFT, in order to enhance blockchain performance [30]. Transactions encompass multiple stages, such as chaincode execution, identity verification, orderer authorization, and peer ledger modifications [20]. APIs and SDKs, specifically Node.js and Java SDKs, are utilized for orchestration, as stated in the official documentation [31]. Entities in Hyperledger Fabric take the form of Docker containers, seamlessly integrated with the host operating system [32]. Scalability is a key focus, addressing peers, organizations, ordering services, and channels [32]. Peers play a vital role, serving dual functions by hosting ledgers and chaincodes and enabling private interactions through channels within their organizations [33]. Notably, utilizing CouchDB enables more efficient query execution compared to other relational databases, leading to reduced latency, especially with simpler queries [33]. Ordering services responsible for ledger validation and updating follow consensus protocols like Paxos or RAFT [20]. The gossip protocol, as outlined in [20], facilitatessystem resilience by ensuring continuous peer communication and updates, even in the face of disruptions. Privacy enhancements, rolled out in version 1.2, now enable authorized participants to have exclusive access to private data collections [33]. The resilient security framework of Hyperledger Fabric is emphasized through advanced features like private data collections and zero-knowledge proof using Identity Mixer (Idemix) [34]. Participants within the system leverage X.509 digital certificates issued by a certificate authority (CA) and authenticated by a membership service provider (MSP) [20]. Beyond the core framework, various projects like Hyperledger Iroha, Burrow, Cello, Composer, and Explorer contribute to the continuous expansion of the Hyperledger family, enriching its overall capabilities [30]. To contextualize our proposed trust framework, Table 4 presents a comparative analysis of the existing blockchain-based threat intelligence sharing systems. The comparison focuses on the employed trust models, blockchain platforms, implementation status, scalability, and unique contributions. While previous works such as those by [PERSON] et al. [35] and [PERSON] and [PERSON] [36] offer foundational trust and sharing mechanisms, they often lack real-world scalability or do not integrate advanced access control. In contrast, our proposed system, TrustShare, introduces a hybrid trust model combining direct and indirect evaluations, leverages Hyperledger Fabric's modular architecture for enhanced scalability, and incorporates CP-ABE for fine-grained access control. This comparative perspective highlights the novelty and practicality of our approach in addressing the current limitations in secure and privacy-preserving threat intelligence sharing.