# Self-Sovereign Identity-Based E-Portfolio Ecosystem
## 2 Background and Related Work
### E-Portfolio  
The e-portfolio system was established in Taiwan in 2019, coinciding with a shift in focus for college admissions from entrance exam results to a greater emphasis on long-term learning performance. The e-portfolio records students' academic performance in high school and enables students to regularly record and edit their files to more accurately and realistically present their characteristics, professional interests, and learning records. Through these files, university reviewers can understand a student's learning performance, which cannot be ascertained through the entrance examination.  
Figure 3 depicts the procedure for uploading e-portfolio files. Currently, the Ministry of Education of Taiwan has created an e-portfolio central database to integrate high school students' e-portfolio files, school grades, and activity records. Students' data are uploaded layer by layer and centralized in a specific organization, which also makes it an attractive target for attackers. Additionally, students are not free to use uploaded files, which can only be used for university admissions reviews.  
In [18], the author delineated three types of traditional e-portfolio systems: The Developmental Portfolio highlights a student's growing skills over time, serving as a developmental tool that incorporates self-assessment and reflection and promotes communication with academic staff. The Assessment Portfolio, on the other hand, demonstrates a student's proficiency in specific areas, employed for continuous or summative evaluations, and assesses their performance based on program standards. The Showcase Portfolio highlights a student's skills and work examples, typically created at the end of a program for potential employers to assess the quality of their work. However, these traditional e-portfolio systems come with challenges, such as the need for constant system activity to prevent student uploads or the necessity for teachers to provide timely feedback to students.  
Some research suggests that the decentralized and immutable features of blockchain are helpful in building a more open and trustworthy educational field [19]. [PERSON] et al. [20] proposed a blockchain system that combines public and private blockchains for online learning evaluation and certification. This architecture not only reduces the complexity of the public blockchain but also maintains the flexibility of the application. [PERSON] et al. [21] proposed a blockchain-based personal portfolio authentication system to improve the centralized storage of student and teacher portfolios in Korean educational institutions (NEIS).  
There are several commercial applications. Turing Certs [22] established a third-party authentication authority, which creates an anti-counterfeiting e-wallet for students to store their certificates. Neitzen [23] proposed an electronic certificate infrastructure based on a private blockchain, which stores the hash of the certificate in the blockchain to ensure the integrity of the certificate. These applications [22; 23] use blockchain technology as their solution, but the services are managed by a single entity, which still has a single point of failure and raises concerns about companies going out of service.  
Figure 3: The process of uploading e-portfolio files [17].