A list of which anonymous keys came into contact with other anonymous keys is never uploaded and is never centralized. You phone only tracks which keys it has s

A list of which anonymous keys came into contact with other anonymous keys is never uploaded and is never centralized. You phone only tracks which keys it has seem and polls the server to see if one of those keys has been uploaded to signal itself as infected. The only way for this system to break privacy is if the app started uploading all keys it came in contact with, and also identified who the uploader is.