The revisions are part of an application program interface, or API, to be used in the companies' contact-tracing proposal, announced on April 10. They are working on a method allowing users to know when they've come into proximity with someone who has later gone on to test positive for COVID-19.
The app employs Bluetooth technology already installed on mobile devices using Apple's iOS system or the Android system largely developed by Google. Working with existing public health apps, users could opt in to using the platform.
Representatives of each company pledged Friday to disable the service after the pandemic is sufficiently contained. The updated system includes security and privacy enhancements demanded by governments and public health authorities, they said.
The actions designed to protect privacy include a change to the cryptography mechanism for the keys used to trace potential contacts. The new method makes it more difficult for anyone to determine how the keys are derived, and then attempt to use that information to track specific individuals. All data will be encrypted.
The system will be called "exposure notification," instead of "contact tracing" to distinguish it from traditional contact tracing practices by public health organizations relying on telephone calls warning individuals that they may have been exposed to someone carrying the virus.