From the docs: “as an additional safeguard, the visual derivatives themselves are matched to the known CSAM database by a second, inde- pendent perceptual hash.

From the docs: “as an additional safeguard, the visual derivatives themselves are matched to the known CSAM database by a second, inde- pendent perceptual hash. This independent hash is chosen to reject the unlikely possi- bility that the match threshold was exceeded due to non-CSAM images that were ad- versarially perturbed to cause false NeuralHash matches against the on-device en- crypted CSAM database.”