The contact tracing data is stored in a format that is readable by many tools. We chose a compact schema to minimize the file size for sharing. The data is recorded the same way, regardless of the country where the data originated. In case the device changes timezone, the readable format contains the currently active time as it was experience by the user in their current location.
JSON format and information that it contains
The data takes shape of a JSON Array of JSON Objects (a collection of all the encounters collected by the device).
timestamp: UTC unixtime of the encounter in milliseconds
uid: an incremented number for every sample that is recorded on the database, just as a counter for records' count
uuid: your Encounter UUID that was randomly generated when running Encounter for the first time
uuid_detected: the UUID of someone that has also Encounter installed and is within 1.5-5 meters from you
readable: a human readable conversion of the timestamp taking into account your device timezone
Example of the exported JSON file content
Offline, local database
The Encounter apps store the data only locally on your device. There is no server or infrastructure requirements to scale the usage of the app. Encounter can be used by any country and any individual with an Android or iPhone. The data can be collected indefinitely, as long as there is internal storage space on your smartphone. At any time, the user may clear the database, and in the process reset the Encounter UUID. This is particularly useful to protect the privacy of those who are tested positively for COVID-19.
For health officials and authorities
We have a tool for authorities to be able to read and make use of the Encounters' data file. This tool can be used to identify potential UUIDs that match the criteria for potential infection for COVID-19. This tool can be used to create and send a personalized instructions per country and authority.
What happens when I share my data?
When a user shares his data, the encounters data collected on the phone is exported to a commonly used JSON file and saved in their smartphone internal and protected storage. These files, if shared, can then be opened in many data analysis tools such as Matlab, R, and others. You can share this JSON file with the authorities in your country over email, WhatsApp, or other applications that support file attachments. If you cancel the share, the file is discarded. A new UUID is assigned to you every time you export your data.