PhotoDNA

[7] Microsoft donated[failed verification] the PhotoDNA technology to Project VIC, managed and supported by the International Centre for Missing & Exploited Children (ICMEC) and used as part of digital forensics operations[8][9] by storing "fingerprints" that can be used to uniquely identify an individual photo.

[12] In the 2010s and 2020s, PhotoDNA was put forward in connection with policy proposals relating to content moderation and internet censorship,[13] including US Senate hearings (2019 on "digital responsibility",[2] 2022 on the EARN IT Act[14]) and various proposals by the European Commission dubbed "upload filters" by civil society[15][16] such as so-called voluntary codes (in 2016[17] on hate speech[18] after 2015 events, 2018[19] and 2022[20] on disinformation), copyright legislation (chiefly the 2019 copyright directive debated between 2014[21] and 2021[22]), terrorism-related regulations (TERREG)[23] and internet wiretapping regulations (2021 "chat control").

[13] By 2019, big tech companies including Microsoft, Facebook and Google publicly announced that since 2017 they were running the GIFCT as a shared database of content to be automatically censored.

[31] As of 2022, PhotoDNA was widely used by online service providers for their content moderation efforts[10][32][33] including Google's Gmail, Twitter,[34] Facebook,[35] Adobe Systems,[36] Reddit,[37] and Discord.

[38] The UK Internet Watch Foundation, which has been compiling a reference database of PhotoDNA signatures, reportedly had over 300,000 hashes of known child sexual exploitation materials.