How iPhone child-safety photo scanning works — and why privacy advocates are worried

If a photo on your phone matches up with one in the database, your phone will attach a “safety voucher” to the photo when it uploads to iCloud. Apple says its employees won’t be able to look at the photos until there have been 30 matches. At that time, the photos will be decrypted, and an Apple employee will look at the matching photos sent by your phone and determine whether it is, indeed, child abuse material. Then Apple will notify NCMEC, which will notify authorities.