High Stakes: Designing a Privacy Preserving Registry

This paper details our experience designing a privacy preserving medical marijuana registry. In this paper, we make four key contributions. First, through direct and indirect interaction with multiple stakeholders like the ACLU of Washington, law enforcement, the Cannabis Defense Coalition, state legislators, lawyers, and many others, we describe a number of intersting technical and socially-imposed challenges for building medical registries. Second, we identify a new class of registries called unidirectional, non-identifying (UDNI) registries. Third, we use the UDNI concept to propose holistic design for a medical marijuana registry that leverages elements of a central database, but physically distributes proof-of-enrollment capability to persons enrolled in the registry. This design meets all of our goals and stands up in the face of a tough threat model. Finally, we detail our experience in transforming a technical design into an actual legislative bill.