# Proxy Signature-Based Management Model of Sharing Energy Storage in Blockchain Environment
## 3 Blockchains and Authentication Technology
### Blockchain Framework of SES  
As a novel information technology, blockchains are not a panacea that deal with all existing problems. The reason for applying blockchains in a scenario is that blockchains have more advantages and a lower cost in this scenario, compared with other technologies. Therefore, the compatibility between blockchains and SES is as follows. First of all, the supply side and the demand side are, respectively, composed of energy storage resources and demanders with different locations, types and capacities. Therefore, SES is a distributed energy network, which is consistent with the distributed and decentralized characteristics of blockchains. In a blockchain, the participants of SES can act as a node to maintain the distributed database with other nodes. The distributed database is more fault-resistant and reliable than the centralized one, and every participant has a database backup locally. Secondly, the demands of SES for fairness, equality and trust can be met by blockchains. According to organizational relation, the SES market is classified into two types: a center-dominated type and decentralized type. For example, the peak regulation market, where SES resources accommodate wind and solar power from different centralized power plants, is dominated by the power grid in China [31]. Under these circumstances, the power grid and other dominant institutions can issue a security statement by using blockchains. The security statement demonstrates that the market is fair and equal through the disclosure and sharing of key information on the blockchain. Although their power will be limited, the trust of the institutions from participants and regulators is improved. On the other hand, the SES market on the user side includes a large number of participants. The status and authority of these participants are equal, and therefore this market is decentralized. Blockchains realize the mutual balance and trust among the participants in a multiparty governance mode, even if the participants do not know each other or are even competitors. Thirdly, the efficient, reliable and safe sharing process of energy storage can be achieved by blockchains. In a platform based on traditional information technologies, it is only a digital medium of the off-line trade. The signing, auditing and executing of contracts, a key step in transactions, still need tedious and time-consuming manual processing, which delays the time of completing a transaction and introduces many human factors that may affect fairness. However, smart contracts areutilized in blockchains to execute the procedure without human intervention. Moreover, blockchains can provide smart contracts with a reliable environment. The use of smart contracts improves the transaction efficiency and reduces the labor cost because the contracts execute automatically once the preset conditions are completed. Except for smart contracts, cryptography tools are another key element in the transaction process, protecting privacy while ensuring information can be verified. A blockchain framework of SES is shown in Figure 3. It can be seen that the blockchain framework consists of a basis layer, core layer, service layer, user layer and cross-layer function. Moreover, a typical transaction process of SES is presented based on the user layer. The transaction process is composed of the following stages:  
S1: Information issuing. In this stage, the participants issue the information about the SES transactions on blockchains. For example, suppliers or demanders can submit the number of the idle energy storage resources in the future and their price. Power grids can issue peak regulation information the next time to make participants understand the state of this market. S2: Transaction matching. In this stage, the supplies and demands are matched based on the market rules and states. More factors, such as power loss, geographical location and facility performance, may be considered in the matching strategy compared to other types of power markets.