# TrustShare: Secure and Trusted Blockchain Framework for Threat Intelligence Sharing
## 6 Conclusions  
This paper introduced _TrustShare_, a novel blockchain-based framework for secure, privacy-preserving, and regulation-compliant cyber threat intelligence (CTI) sharing. Based on a permissioned architecture powered by **Hyperledger Fabric**, TrustShare harnesses the strengths of distributed ledger technologies alongside **fine-grained cryptographic access control** to enable secure, scalable, and trustworthy collaboration across multiple organizations. At the heart of TrustShare lies an advanced implementation of **Ciphertext-Policy Attribute-Based Encryption (CP-ABE)**, facilitating dynamic policy-driven data exchange. Moving beyond traditional attribute models, our framework incorporates **temporal (\"time-bombing\") constraints, controlled revelation mechanisms**, and **location interlocking**, allowing data owners to stipulate precisely when, how, and where shared intelligence may be accessed. These enhancements provide unprecedented control over sensitive threat data whilst maintaining operational flexibility and adherence to regulatory frameworks. To ensure interoperability and applicability in real-world settings, the framework integrates the **STIX and TAXII** standards for structured threat data representation and employs the **IPFS** for secure decentralized storage. In compliance with the **General Data Protection Regulation (GDPR)** and the **right to be forgotten (RtbF)**, the design embeds privacy-preserving data policies and revocation capabilities, enforced through chaincode and certificate authority mechanisms. Empirical assessments indicate that TrustShare achieves low-latency performance, scalable throughput, and high resource efficiency across various deployment environments, including containerized infrastructures orchestrated with Kubernetes. Furthermore, the security architecture--comprising role-based endorsements, endorsement anonymity (via FCsLRS), and network segmentation--demonstrates strong resilience against common attack vectors and insider threats. Nevertheless, several challenges persist. The computational cost associated with complex CP-ABE policies and encrypted operations may impact scalability under real-time demands. The current framework assumes a partially trusted model among organizational participants. Therefore, establishing comprehensive inter-domain trust governance remains a significant avenue for further exploration. Future work will focus on enhancing TrustShare's adaptability, efficiency, and long-term resilience. This includes the incorporation of context-aware access controls driven by dynamic threat scoring to enable real-time policy adjustments, and improvements to policy enforcement and compilation mechanisms to support scalability in attribute-rich environments. Additionally, the integration of privacy-preserving artificial intelligence is envisioned to facilitate collaborative threat prioritization and anomaly detection across distributed actors. To ensure future-proof confidentiality, ongoing research will also explore post-quantum cryptographic alternatives to the current CP-ABE scheme, protecting against emerging quantum-capable adversaries. Field trials within national and sector-specific CTI alliances are planned to further evaluate the robustness, practicality, and compliance of the system under operational conditions. In summary, TrustShare exemplifies how the synthesis of permissioned blockchain, advanced cryptographic policy control, and decentralized storage can support the creation of a **trustworthy**, **sovereign, and regulation-aligned** platform for the next generation of cyber threat intelligence sharing. H.A., Project administration, Conceptualization, Methodology, Formal analysis, Investigation, Software development, Writing--original draft, Writing--review and editing, Validation, Resources. W.J.B., Supervision, Validation, Review and editing, Resources. J.A., Supervision, Validation, Review. M.A., Validation, Review. M.S.K., Validation, Review. I.W., Validation, Review.