[{"data":1,"prerenderedAt":141},["ShallowReactive",2],{"content:\u002Fglossary\u002Fhash-matching":3,"ArticleBody_FxN370lqXAU6WSdd7lJD7szOkVdXvwiObPjaoqt1Mjo":136},{"kind":4,"path":5,"locale":6,"title":7,"htmlTitle":8,"description":9,"navTitle":7,"published":10,"updated":10,"alternates":11,"breadcrumbs":12,"indexable":20,"twin":21,"collection":22,"slug":23,"file":24,"content":25,"hub":18,"titleEm":27,"eyebrow":17,"lead":28,"cta":27,"faq":29,"faqJsonLd":45,"sources":51,"related":113,"topic":27,"jsonLdType":134,"blocks":135,"shortDefinition":28,"feed":20},"term","\u002Fglossary\u002Fhash-matching","en","Hash matching","Hash Matching in Content Moderation · Detectivision","Hash matching compares an upload's fingerprint with lists of known illegal images such as CSAM. How it works, who offers it, and how classifiers differ.","2026-10-16T18:00:00+03:00",[],[13,16,19],{"name":14,"path":15},"Home","\u002F",{"name":17,"path":18},"Glossary","\u002Fglossary",{"name":7,"path":5},true,"\u002Fglossary\u002Fhash-matching.md","glossary","hash-matching","content\u002Fen\u002Fglossary\u002Fhash-matching.md",{"collection":26,"path":5},"glossary_en",null,"Comparing a file's fingerprint, its hash, with lists of hashes of known illegal material, to find copies and near copies of it.",[30,33,36,39,42],{"q":31,"a":32},"What is the difference between a cryptographic and a perceptual hash?","A cryptographic hash, such as SHA-256, changes completely when one byte of the file changes, so it matches only exact copies. A perceptual hash, such as PhotoDNA or PDQ, is computed from what the image looks like, so a resized or re-saved copy gets a hash close to the original's, and a match means the distance between two hashes is small enough.",{"q":34,"a":35},"Can hash matching find new CSAM?","No. A hash list holds only material that has already been found and confirmed, so a match points to a copy of something known. New material needs a classifier and trained people. Specialist providers offer both: Thorn's Safer, for example, pairs hash matching with a classifier for material not seen before.",{"q":37,"a":38},"Who can get access to CSAM hash lists?","Access is restricted, and each provider sets its own terms. NCMEC shares its list with electronic service providers, which use it on a voluntary basis. IWF Members use the IWF Hash List under licence. Microsoft's PhotoDNA Cloud Service is free for qualified customers. Check the provider's own criteria before you plan around a list.",{"q":40,"a":41},"Can a hash be turned back into the image?","Microsoft says no for PhotoDNA: its hash \"is not reversible, and therefore cannot be used to recreate an image\". A cryptographic hash such as SHA-256 is designed to be one-way. That is why providers can share lists of hashes of illegal images instead of the images themselves.",{"q":43,"a":44},"Does Detectivision detect CSAM?","No. Detectivision does not offer hash matching, CSAM detection or age estimation, and it does not report to NCMEC, the IWF or any authority. Its image flags are hate, scam, sexual and violence, and a sexual flag says nothing about the age of anyone in an image.",[46,47,48,49,50],{"q":31,"a":32},{"q":34,"a":35},{"q":37,"a":38},{"q":40,"a":41},{"q":43,"a":44},[52,57,61,64,67,71,75,79,82,86,90,94,98,102,106,109],{"title":53,"url":54,"publisher":55,"accessed":56},"PhotoDNA","https:\u002F\u002Fwww.microsoft.com\u002Fen-us\u002Fphotodna","Microsoft","2026-10-16",{"title":58,"url":59,"publisher":60,"accessed":56},"PDQ reference implementation (README, facebook\u002FThreatExchange, BSD licence)","https:\u002F\u002Fgithub.com\u002Ffacebook\u002FThreatExchange\u002Ftree\u002Fmain\u002Fpdq","Meta",{"title":62,"url":63,"publisher":60,"accessed":56},"The TMK+PDQF video-hashing algorithm and the PDQ image-hashing algorithm (hashing.pdf, facebook\u002FThreatExchange)","https:\u002F\u002Fgithub.com\u002Ffacebook\u002FThreatExchange\u002Fblob\u002Fmain\u002Fhashing\u002Fhashing.pdf",{"title":65,"url":66,"publisher":60,"accessed":56},"Open-Sourcing Photo- and Video-Matching Technology to Make the Internet Safer (1 August 2019)","https:\u002F\u002Fabout.fb.com\u002Fnews\u002F2019\u002F08\u002Fopen-source-photo-video-matching\u002F",{"title":68,"url":69,"publisher":70,"accessed":56},"Helping Child Survivors: The Fight to Remove Sex Abuse Images (15 April 2024)","https:\u002F\u002Fwww.missingkids.org\u002Fblog\u002F2024\u002Fhelping-child-survivors-fight-to-remove-sex-abuse-images","National Center for Missing & Exploited Children",{"title":72,"url":73,"publisher":74,"accessed":56},"Image Hash List","https:\u002F\u002Fwww.iwf.org.uk\u002Four-technology\u002Four-services\u002Fimage-hash-list\u002F","Internet Watch Foundation",{"title":76,"url":77,"publisher":78,"accessed":56},"Safer solutions (CSAM and CSE detection)","https:\u002F\u002Fsafer.io\u002Fsolutions\u002F","Thorn",{"title":80,"url":81,"publisher":78,"accessed":56},"Safer Partnership Criteria","https:\u002F\u002Fsafer.io\u002Fsafer-partnership-criteria\u002F",{"title":83,"url":84,"publisher":85,"accessed":56},"Lantern","https:\u002F\u002Ftechnologycoalition.org\u002Fprograms\u002Flantern\u002F","Tech Coalition",{"title":87,"url":88,"publisher":89,"accessed":56},"What is Azure Content Moderator? (updated 5 June 2026)","https:\u002F\u002Flearn.microsoft.com\u002Fen-us\u002Fazure\u002Fai-services\u002Fcontent-moderator\u002Foverview","Microsoft Learn",{"title":91,"url":92,"publisher":93,"accessed":56},"Law No. 5651, consolidated text (Article 2(1)(s), definition of a social network provider)","https:\u002F\u002Fwww.mevzuat.gov.tr\u002Fmevzuatmetin\u002F1.5.5651.pdf","Mevzuat Bilgi Sistemi",{"title":95,"url":96,"publisher":97,"accessed":56},"Law No. 7578, Article 22, adding paragraph 23 to Additional Article 4 of Law 5651 (Resmî Gazete 33240, 1 May 2026)","https:\u002F\u002Fwww.resmigazete.gov.tr\u002Feskiler\u002F2026\u002F05\u002F20260501-1.htm","Resmî Gazete",{"title":99,"url":100,"publisher":101,"accessed":56},"UAE's Child Digital Safety Law: What Every Digital Platform and ISP Should Know (law-firm summary, 9 January 2026)","https:\u002F\u002Fwww.lw.com\u002Fen\u002Finsights\u002Fuaes-child-digital-safety-law-what-every-digital-platform-and-isp-should-know","Latham & Watkins",{"title":103,"url":104,"publisher":105,"accessed":56},"Online Safety Act: Illegal Content Codes of Practice 2024, explanatory memorandum (17 December 2024)","https:\u002F\u002Fwww.gov.uk\u002Fgovernment\u002Fpublications\u002Fonline-safety-act-illegal-content-codes-of-practice-2024-explanatory-memorandum\u002Fonline-safety-act-illegal-content-codes-of-practice-2024-explanatory-memorandum","GOV.UK",{"title":107,"url":108,"publisher":105,"accessed":56},"Explanatory memorandum: draft amendments (No. 2) to the Illegal Content Codes of Practice for user-to-user services (18 June 2026)","https:\u002F\u002Fwww.gov.uk\u002Fgovernment\u002Fpublications\u002Fonline-safety-act-draft-amendments-to-the-protection-of-children-code-of-practice-for-user-to-user-services\u002Fexplanatory-memorandum-draft-amendments-no-2-to-the-illegal-content-codes-of-practice-for-user-to-user-services-and-draft-amendments-to-the-protec",{"title":110,"url":111,"publisher":112,"accessed":56},"Service status, GET \u002Fapi\u002Fv1\u002Fstatus","https:\u002F\u002Fapi.detectivision.ai\u002Fapi\u002Fv1\u002Fstatus","Detectivision",[114,118,122,126,130],{"path":115,"title":116,"description":117},"\u002Fnsfw-detection-api","NSFW detection","Detect nudity and sexual content in images, and sexual language in text written in ten languages, with one API call and a confidence for each finding.",{"path":119,"title":120,"description":121},"\u002Fglossary\u002Fage-assurance","Age assurance","Age verification checks how old a user is; moderation checks what they post. The terms, the methods UAE, UK, EU and Turkish rules accept, and who does what.",{"path":123,"title":124,"description":125},"\u002Fglossary\u002Fcontent-moderation-api","Content moderation API","A content moderation API checks the text or images you send and says what it found and how sure it is. How requests, results, prices and decisions work.",{"path":127,"title":128,"description":129},"\u002Fregulations\u002Fturkey-social-media-age-law","Turkey's under-15 social media rules: what platforms must do","From 1 November 2026, social networks reachable from Turkey may not serve under-15s and must verify ages. Scope, deadlines and every duty, with article numbers.",{"path":131,"title":132,"description":133},"\u002Fregulations\u002Fuae-child-digital-safety-law","UAE Child Digital Safety Law: what platforms must do, and by when","The UAE Child Digital Safety Law covers platforms operating in or aimed at the UAE. Who is in scope, each duty, the expected 2027 deadline and what is pending.","Article",false,["Island",137],{"key":138,"result":139},"ArticleBody_FxN370lqXAU6WSdd7lJD7szOkVdXvwiObPjaoqt1Mjo",{"head":140},{},1792166153937]