Much simpler would simply be the ability to exclude certain contacts (your doctor, therapist, or teacher etc). Additionally, it would be great to not share met

Much simpler would simply be the ability to exclude certain contacts (your doctor, therapist, or teacher etc). Additionally, it would be great to not share metadata about contacts (ie, don't share that I have this person listed as my sister). It's quite difficult to have a privacy preserving API system that's on-device because people could pre-compute a rainbow table (phone numbers are only 10-ish digits long). If the API is provided by Apple using their servers, this might work.