It starts with a rebrand, no longer being called contact tracing but “exposure notification,” while subtle it may help ease any pre-existing concerns people had. Additionally, the companies have made clear that Bluetooth metadata from users devices will remain encrypted, and that the keys that identify a device, will be “generated every day.”
They’ve also announced that their system will not measure one person’s contact with someone else for more than 30 minutes at a time and that it has adopted AES data encryption standards which differs from the previous system, HMAC.
In terms of the actual API, it will now keep track of how long it has been since a user had contact with someone who tested positive for COVID-19 in order to determine the next steps that should be taken.
Apple and Google intend to rollout the new API on the 28th of April, hoping for a smooth international rollout. Whether that will happen, is a matter of how governments will react to the recent changes.