All photos of the same mobile phone certainly have a unique fingerprint. Not only the EXIF, also the dead pixels and the unique pattern of low intensity pixels.

All photos of the same mobile phone certainly have a unique fingerprint. Not only the EXIF, also the dead pixels and the unique pattern of low intensity pixels. If you want to protect user privacy, a unique identifier is not enough. If they posted a gay profile somewhere, a professional profile somewhere else, they will be forever linked.