Enabling Privacy Preserving Record Linkage Systems Using Asymmetric Key Cryptography.

We present a systemic approach to devise and deploy Privacy Preserving Record Linkage (PPRL) systems using asymmetric key cryptography and illustrate the strengths of such an approach. With our approach, the security implications of sharing a common secret salt across the network may be avoided, allowing the local participating sites to use private keys along with the current cryptographic hashes to maximally secure their own data. In addition, the final cyphertext tokens are compatible with those used by existing record linkage modules, allowing seamless integration with the existing PPRL infrastructures for downstream analysis. Finally, study-specific hash production requires action only by the central party. The main intuition for this work is derived from how asymmetric key approaches have enabled internet-scale applications. We demonstrate that such a design, where the local sites no longer need special-purpose software, affords greater flexibility and scalability for large scale multi-site linkage studies.