Blockchain is making headlines due to it promises to provide a decentralized, transparent, tamper-resistant, traceable and verifiable historical transaction records that can resist faults of any single node. According to the latest data from State of the Dapps, developers have currently released 3,717 Decentralized Applications (DApps), only three have an average of more than 10,000 daily active users. Most of the real-world DApps exercise little of their potential power. The key reason is that the current permissioned blockchain systems suffer from poor performance and lack of confidentiality. To address this issue, we present Hybridchain, a system that combines blockchain with Trusted Execution Environment (TEE). Hybridchain decouples computation from consensus and adopts hierarchical network to minimize the computational burden and latency of on-chain execution by performing most of the heavy-weight computation off-chain. Hybridchain leverages secure communication protocols to enable each participant to share transaction data in a secure way. To mitigate the small enclave memory restriction of TEE, Hybridchain extends the enclave memory that allows blockchain applications running in TEE to securely store transaction records to the whole key-value storage codes placed outside of TEE. Analysis and experiments of sealed-bid auction show that Hybridchain can support confidentiality-preserving along with high performance.

Wide Area Protection System (WAPS) undertakes the important task of maintaining system reliability and stability when the power system is subject to abnormal or predetermined unstable conditions. The existing WAPS adopts a centralized mechanism to record and audit communication messages, which faces the risk of excessive authority and tampering with communication records and audit logs, thus making it impossible to achieve true transparency and fairness. Due to the involvement of multiple parties and equipment maintained by different manufacturers in the communication of WAPS, there are difficulties in tracing the cause of the accident and determining the at-fault party following misoperations and miss trips. To address this issue, we propose a semi-centralized blockchain system with multi-chain for auditing communications of WAPS. We first propose a semi-centralized system architecture according to the system architecture and management requirements of WAPS. Then, we utilize the blockchain network as a self-recording channel to achieve tamper-proof and non-repudiation verification interaction. We also design a multi-chain structure and classification node mechanism to meet the communication auditing requirements of multiple WAPS. We have designed a new block structure that conforms to the communication protocol of WAPS. To reduce the storage burden caused by the ever-expanding blockchain ledger, we propose a deletable blockchain scheme while maintaining the integrity and security of blockchain. Analysis and experiments show that the proposed blockchain system can support the secure, transparent, tamper-proof and traceable communication recording and auditing of WAPS along with high performance.