PhotoDNA

Perceptual hashing that matches images against known abuse material.

About PhotoDNA

PhotoDNA is a technology developed by Microsoft in 2009 in partnership with Dartmouth College to aid in finding and removing known images of child exploitation. Microsoft provides it for free to qualified organizations, including technology companies, developers, and non-profit organizations, for the purpose of combatting child exploitation.

PhotoDNA is available for free to law enforcement and tool providers. Microsoft donated PhotoDNA to the National Center for Missing & Exploited Children (NCMEC). In 2015, Microsoft made PhotoDNA available as a service on Azure.

Drafted from microsoft.com · not yet confirmed by Microsoft

How it works

PhotoDNA is the perceptual hash Microsoft developed with Dartmouth in 2009 and the reason known CSAM detection works at internet scale. It converts an image to a hash that stays stable through resizing, recompression and small edits, so a match to a known abuse image holds even after the file has been altered. NCMEC, IWF and most major hash lists are available in PhotoDNA format.

Microsoft provides it as a cloud service for qualifying organizations; you send images (or run the hashing locally in some arrangements) and match against the lists you have. There's also a video variant.