Delegated Provision of Personal Information and Storage of Provided Information on a Blockchain Ensuring Data Confidentiality

Personal information leakage is very harmful as it can lead to additional attacks using leaked information as well as privacy invasion, and it is primarily caused by hacking server databases of institutions that collect and store personal information. We propose a scheme that allows a service-requesting user to authorize a secure delegated transfer of his personal information to the service provider via a reliable authority and enables only the two parties of the service to retrieve the provided information stored on a blockchain ensuring data confidentiality. It thus eliminates the necessity of storing customer information in the service provider's own database. As a result, the service provider can serve customers without requiring membership registration or storing personal information in the database, so that information leakage through the server database can be completely blocked. In addition, the scheme is free from the risk of information leakage and subsequent attacks through smartphones because it does not require a user’s smartphone to store any authentication credential or personal information of its owner.