Revision History

v1.1 - April 22, 2020

• Renamed “Contact Tracing” to “Exposure Notification” throughout the document.

• Temporary Exposure Keys (previously known as Daily Tracing Keys) are now randomly generated and no longer derived.

• AES is now used instead of HMAC<SHA256> for improved performance.

• Encryption of associated metadata is now provided.

• Reformatted the title page and table of contents for consistency across documents.

• Overview

• External Functions

• Key Schedule for Exposure Notification

• Positive Diagnosis

• Value Matching of Positive Users

• Privacy Considerations

• Test Vectors

• Revision History