Privacy-Enhancing Technologies

In the course of the digital transformation, increasing amounts of data are exchanged digitally. Business processes and regulatory compliance requirements that demand additional degrees of verifiability of the exchanged information and the accountability of corresponding stakeholders further add to the volume and sensitivity of this data. At the same time, users’ personal information calls for enhanced protection and organizations are concerned about ensuring the confiden-tiality of business-relevant information, as well as complying with data protection obligations. Thus, the tension between verifiability and accountability on the one hand and data minimization on the other hand has become a major concern. Maybe counterintuitively, decentralization technologies can exacerbate this issue, because they expand the number of stakeholders responsible for data processing and storage, which may increase verifiability/accountability and data minimization requirements at the same time. Privacy-enhancing technologies (PETs) provide a means to mitigate this seemingly fundamental trade-off. In this chapter, we give an overview of the technical foundations of PETs and reflect on how to leverage them in decentralized information systems to achieve verifiable and accountable results without disclosing excessive information. We particularly focus on zero-knowledge proof (ZKP)-based constructions.