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> A cryptographic hash + file size combo is unlikely to have a false positive within our lifetime The chance of a "technical" false positive is tiny, but they

> A cryptographic hash + file size combo is unlikely to have a false positive within our lifetime The chance of a "technical" false positive is tiny, but they need to look all false positives: If some joker sends you a lewd picture through WhatsApp, WhatsApp by default saves every picture to your photo library, then you are now on the naughty list. Good luck trying to explain yourself out of that one.

ziml77 5y ago
WhatsApp saves all received images to your library? That seems hard to believe. I can't imagine that anyone would appreciate having their personal photo collection cluttered with other peoples photos and all of the meme images that people share.
- speleding 5y ago
  It's a setting, called "Save to camera roll". Default is on.
  - ziml77 5y ago
    Strange. Is that a desirable feature for WhatsApp users? I must be overlooking a use case that makes that a sensible default.
tyingq 5y ago
The context there was that a typical CSAM hash like PhotoDNA is NOT a cryptographic hash, but a perceptual one, which DOES have notable false positive issues.