ABSTRACT
This chapter contributes to research on the issue of data double spending, or unauthorized secondary use of individuals' data. The chapter describes two solutions that provide decentralized marketplaces for individuals to share their health data for purposes of AI-driven health research – one that uses the Hyperledger Indy/Aries protocol – the ‘Self-Sovereign’ data marketplace – and the other an Ethereum-based solution – the ‘Ocean Protocol’ data marketplace. Based on an implementation of applications using both protocols, the chapter evaluates the strengths and weaknesses of each data marketplace vis-a-vis adherence to fair data processing principles and protecting individuals from data double spending. The chapter contributes to a clearer articulation of fair blockchain-based data processing and the issue of data double spending, an assessment of how well each solution addresses the issue, and possible directions for research aimed at preventing data double spending.
