Pseudonymisation with Break-the-Glass Compatibility for Health Records in Federated Services

Pseudonymisation is a major requirement in recent data protection regulations, and of especial importance when sharing healthcare data outside of the boundaries of the affinity domain. However, healthcare systems require important break-the-glass procedures, such as accessing records of patients in unconscious states. Our work presents a pseudonymisation protocol that is compliant with break-the-glass procedures, established on a (t, n)-threshold secret sharing scheme and public key cryptography. The pseudonym is safely derived from a fragment of public information without any private secret requirement. The protocol is proven secure and scalable under reasonable assumptions.