Provably secure blockchain privacy-preserving smart contract centric dynamic group key agreement for large WSN

The contemporary Group Key Agreement (GKA) entails lightweight computing, reduced communication, decentralized certification, personal privacy protection, traceability, and accountability. In this paper, we adopted blockchain technology in GKA to incorporate these features. This work first presents a blockchain-based two-party Elliptic Curve Diffie-Hellman key agreement. Subsequently, we extend it to an n-party key agreement to propose a Blockchain-based Dynamic Authenticated Contributory Group Key Agreement (BDACGKA). In this technique, the privacy-preserving smart contract (PPSC) acts as a Group Controller in the first round and generates two-party shared keys with each group member. The PPSC computes partial group keys in the second round and sends them to the respective group members. After receiving the partial group keys sent by the PPSC, each group member generates the group key by multiplying the received product with its shared key. Furthermore, we built a Formal Security Model for the proposed protocol. Finally, the performance analysis demonstrates that the proposed protocol is more proficient than the examined protocols and highly adaptable to large wireless sensor networks.