The goals of this project were to remove the sensitivity of personally-identifiable information (PII) as a challenge to achieving interoperability, to share data that can be linked among organizations, to avoid adding specific data elements to data sharing agreements (DSAs) like Social Security numbers (SSNs), to reduce security risks, and to ensure an open-source concept for future development and costs savings.

We created a Solution for Identifying Linkage Keys (SILK) to remove barriers to interoperability based on open-source technology. SILK transforms an SSN or other sensitive value into a secure hashed value. Two or more partners can use SILK with the same Salt (i.e., key) to convert sensitive fields into secure hashed values. Partners can then link their data using the hashed values (instead of a sensitive value like SSN) while never sharing the sensitive value.

Acknowledgment: The project described herein was supported by the Human Services Interoperability Innovations program, grant number 90PD0308, with the amount of $599,992 from the Office of Planning, Research and Evaluation, Administration for Children and Families, U.S. Department of Health and Human Services. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Office of Planning, Research and Evaluation, the Administration for Children and Families, or the U.S. Department of Health and Human Services.

• SILK uses Application Programming Interface (API) technology to connect to a secure server that hashes data.
• The solution allows for systems to securely generate alternative, unique, and linkable hash values derived from original IDs.
• The source system logs in, submits the variables, and gets the hashed values.
• SILK is secure because the same Salt must be used.
• Organizations do not have to share PII but can share full records about the same individuals/cases.