# Self-Sovereign Identity-Based E-Portfolio Ecosystem
## 3 System Design
### Operation Model
#### 3.1.2 E-Portfolio Application Blockchain (EApp-Chain)  
In the EApp-chain, we utilize HLF to construct a multi-channel ecosystem. Our EApp-chain comprises two channels to tackle two key issues--data credibility and user authorization. By leveraging the multi-channel mechanism provided by HLF, we effectively segment the business logic and improve ledger privacy. Before utilizing the App-chain, users must first create an identity on the DID-chain and upload the necessary registration material to their _Plcon_ on the DID-chain based on the blockchain framework utilized in the ecosystem. Upon registration at any high school, users are bestowed with a self-sovereign e-portfolio identity (SSeI). This primary identity allows users to easily log in to any participating entity, in which they can use their SSE to manage access within the e-portfolio ecosystem. The intricacies of the login and registration workflow will be expounded upon in Section 4, and an in-depth overview of the user journey and authentication processes within this system is provided. Figure 5 presents the structure of our proposed e-portfolio ecosystem. In this system, students are equipped with a self-sovereign identity, allowing them to govern data authorization without resorting to conventional text password logins. Reviewers gain direct access to reliable review data from high schools and activity organizations, eliminating the need for these institutions to upload student data to a centralized database. Data from various sources, including awards, exam scores, and extracurricular activities, are subject to verification by educational units. The system involves multiple entities, such as the certificate and award channel (_CaAch_), access control channel (_ACch_), central education unit (_CEU_), local education unit (_LEU_), high school (_HS_), activity organization (_AO_), student (_STU_), and reviewer (_RE_). Each entity plays a specific role, contributing to a decentralized and secure framework for the management and access of educational data. Further details on the roles and interactions of these entities are discussed in subsequent sections. The roles of these parties are explained in detail as follows:  
* Certificate and Award Channel (_CaAch_): In the _CaAch_, _CEU_ and _LEU_ serve as peer nodes to share the ledger1. Organizations that are not part of this channel, such as _HSs_, _REs_, and _AOs_, must obtain client credentials from peer node organizations. This channel stores information about _AO_s and _REs_ that have passed the education unit's audit, as well as each user's award information. The _CEU_ and _LEUs_ form an audit alliance to jointly maintain the reliability and credibility of users' awards. * Access Control Channel (_ACch_): The _ACch_ plays an important role in the e-portfolio ecosystem by allowing the _CEU_, _LEUs_, and _HSs_ to act as peer nodes and share the ledger2 as shown in Figure 5. This channel stores the authorization status of users, with each user having a unique access control instance (_ACins_) that can only be updated by themselves. The access control manager contract is tasked with managing access control in the ecosystem, ensuring that only permitted users can access their respective data. By segmenting this functionality into a separate channel, the e-portfolio ecosystem can effectively manage user authorization and access control, which helps keep user data secure and private. * Central Education Unit (_CEU_): The role of the _CEU_ is crucial in the e-portfolio ecosystem, as it is responsible for organizing college entrance exams and supervising the overall system. As part of its responsibilities, the _CEU_ maintains a root-ca server, which issues identity certificates to reviewers. A root-ca server is a trusted entity that issues digital credentials to authenticate the identity of users or devices in a network. The certificates issued by the root-ca server are considered trustworthy because they are signed by the root-ca's \(P_{r}k\).