**3. Study of Blockchain Technology**

This study on blockchain technology focuses on the six layers of the blockchain, which are: Application Layer, Contract Layer, the Actuator Layer, Consensus Layer, Network Layer and Data Layer. Detailed technical research of studies is shown in Table 2.

**Table 2.** Different science and technology concerns for each layer at China and outside China.



**Table 2.** *Cont.*

For the Application Level, the China's studies focus on social industries such as ecommerce, education, taxation, medical care, intellectual property and social governance. This paper [78] believes that the introduction of blockchain, edge computing and other technologies under the distributed architecture computing network can provide digital power for smart earth applications. International studies focus more on the economic and financial fields such as investment, payment, identification, anti-money laundering, business process re-engineering, finance, etc. For the Contract Layer, the Chinese studies focus on tying up the industrial chain through the contract state machine, to implement its designed smart contract into the industry. This paper [79] studies a new type of decentralized threshold signature protocol. By combining distributed the key generation protocol and BLS signature, a set of threshold signature protocol with fixed signature length that can be participated by multiple parties is designed. The international studies focus more on the blockchain smart contract itself, through the design of the contract layer protocol to serve the blockchain network. For the Actuator Layer, both Chinese and international studies focus on the design of reputation-based game model. In terms of preferences for technical scenarios' landing. This paper [80] proposes a two-party elliptic curve digital signature algorithm suitable for blockchain. Through the mathematical logic of the given signature algorithm and its security model, it is integrated into the blockchain for evaluation, which proves the feasibility of the scheme. Chinese studies focus on the integration of actuation and data sharing scenarios, while international studies focus on the blockchain network improvements. For the Consensus Layer, both Chinese and international studies prefer the improved consensus algorithm for existing PoW, (D) PoS and PBFT. Few new consensus algorithms have been proposed. For the Network Layer, China preferences is for efficiency improvements through external software and services, while the international preference is more focused on technical improvements to the blockchain network layer. For the Data Layer, Chinese preference is to apply data in the security field, while the international focus is more on research and improvements of the blockchain data layer, such as data structure, data expansion and chain structure improvement. For example, in the case of ensuring data security and credibility with the help of the blockchain double-chain structure, the endogeneity is improved [81]. The problem of low efficiency of data interaction between middle and platform, etc.

To sum up, based on the six levels of analysis mentioned above, we can clearly see the similarities and differences between Chinese and foreign research directions: At the Application Level, China's attention is paid more to the application of actual scenarios, while international attention is paid to the application in the financial field; at the Contract Layer, China's focus on the application of smart contracts in the industrial chain, while the international research on the contract itself has been strengthened; in Actuator Layer, both Chinese and international studies focus on the design of game model; in Consensus Layer, both are researching How to improve the consensus mechanism; in Network Layer, China attaches great importance to external software and services, while the international community pays more attention to improving the blockchain network itself; In Data Layer, domestic data is used more in the field of security, while the international community pays more attention to the research of the data layer itself.
