Practical privacy-preserving protocols for criminal investigations

Social Network Analysis (SNA) is now a commonly used tool in criminal investigations, but evidence gathering and analysis is often restricted by data privacy laws. We consider the case where multiple investigators want to collaborate but do not yet have sufficient evidence that justifies a plaintext data exchange. We propose a practical solution that allows an investigator to expand his current view without actually exchanging sensitive private information. The investigator gets a partially anonymized view of the entire social network, while preserving his known view.