  The emerging blockchain technology has enabled various decentralised
applications in a trustless environment without relying on a trusted
intermediary. It is expected as a promising solution to tackle sophisticated
challenges on personal data management, thanks to its advanced features such as
immutability, decentralisation and transparency. Although certain approaches
have been proposed to address technical difficulties in personal data
management; most of them only provided preliminary methodological exploration.
Alarmingly, when utilising Blockchain for developing a personal data management
system, fictions have occurred in existing approaches and been promulgated in
the literature. Such fictions are theoretically doable; however, by thoroughly
breaking down consensus protocols and transaction validation processes, we
clarify that such existing approaches are either impractical or highly
inefficient due to the natural limitations of the blockchain and Smart
Contracts technologies. This encourages us to propose a feasible solution in
which such fictions are reduced by designing a novel system architecture with a
blockchain-based "proof of permission" protocol. We demonstrate the feasibility
and efficiency of the proposed models by implementing a clinical data sharing
service built on top of a public blockchain platform. We believe that our
research resolves existing ambiguity and take a step further on providing a
practically feasible solution for decentralised personal data management.
