Blockchain-based Personal Data Trading System using Decentralized Identifiers and Verifiable Credentials

As the needs for personal data increase due to the advent of the AI era, many companies are collecting their users' data and using it to advance the service. As the use of personal data increases, the value of personal data also increases. Although these valuable personal data are generated by individuals, only centralized service providers get profit from the data. In this paper, we propose a blockchain-based personal data trading system using DID (Decentralized Identifiers) and VC (Verifiable Credentials). Our proposed system allows users to collect personal data in their own data storage provided by the system. DID and VC are used to authenticate the user's identity and to prove ownership of the data without any centralized systems, respectively. The integrity of the traded data and the history of the transactions are ensured by Hyperledger Fabric, which is a decentralized infrastructure composed of consortium blockchain nodes. We show how our system works by implementing the monitoring system that provides the current status of the user's data and trading. We verify that two end entities including a seller and a buyer can complete personal data trading by using our proposed system without centralized service providers.