UK proposes hash-matching rules to combat intimate image abuse in search results
Ofcom’s proposed measure would add intimate image abuse detection duties to illegal content codes for search services.
The UK government has published draft amendments to the Illegal Content Codes of Practice for search services under the Online Safety Act, proposing new measures to help detect intimate image abuse content. The amendments, published on 1 June, would add a recommended measure for large general search services to use hash-matching technology to detect intimate-image abuse content.
According to the draft, Ofcom prepared the amendments under section 41 of the Online Safety Act and submitted them to the Secretary of State on 15 May. The document was presented to Parliament under section 43 of the Act and is due to lie before both Houses for 40 days.
The proposed measure, designated ICS C8, would apply to providers of large general search services. The measure recommends the use of perceptual hash matching to identify known intimate image abuse content, or cryptographic hash matching where perceptual matching is not supported by the provider’s hash database.
Under the proposal, content matching an unverified hash for the first time would be treated as potentially illegal and subjected to review under Ofcom’s search moderation procedures. Other matches may be treated as illegal content or reviewed as suspected video and image abuse, depending on the provider’s assurance in the detection outcomes.
The amendments also set expectations for human moderator review, regular updates to hash databases, removal of hashes found not to relate to intimate image abuse content, and reviews of precision and recall at least every six months. Ofcom said the proposed measure includes safeguards intended to protect freedom of expression and privacy rights while supporting the detection of illegal content.
Why does it matter?
The proposal reflects growing efforts by regulators to address the spread of non-consensual intimate imagery, including AI-generated content, through proactive detection and moderation measures.
By encouraging the use of hash-matching technologies, UK authorities aim to reduce the repeated circulation of known abusive material while maintaining safeguards for privacy and freedom of expression.
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