The Internet Watch Foundation has announced that it will be taking active steps to prevent the distribution of child sexual abuse images online — a step change from it’s previous approach of only dealing with reported images. 

Established in 1997, the Internet Watch foundation (IWF) is a registered charity that works with Internet Service Providers, law enforcement agencies, and online businesses such as BT, Facebook and Google to identify and remove child sexual abuse content hosted in the UK and abroad.

The change in IWF policy means images identified following reports from internet users and IWF partners will now be supplemented by illegal images actively sought out by trained IWF analysts. Each image will then be assigned a unique ‘digital fingerprint’ — known as a ‘hash’ — that makes it instantly identifiable, without subsequent reference to its content.

The technology means that once vetted by the IWF, illegal images can be routinely identified by computer using the list of image hashes alone, avoiding further (and potentially distressing) human intervention. The hash list also means that in addition to identifying those already online, images can now be identified and blocked during attempted uploads to IWF partners web hosting services, reducing the ability for them to be shared online. 

The IWF already takes action to remove around 500 offending ‘web addresses’ each day in the UK alone, either by contacting web hosting companies to get web sites taken offline or by ISPs adding sites to block lists.

When combined with data from the Home Office’s new Child Abuse Image Database, the new image hash list means that the IWF has the potential to deal with millions of images much more effectively.

“The IWF Hash List could be a game-changer and really steps up the fight against child sexual abuse images online,” said IWF CEO Susie Hargreaves. “This is something we have worked on with our Members since the Prime Ministers’ #WePROTECT summit last December. We’ll soon be able to offer the hash list to all IWF Members, who are based around the world.”

It’s worth noting that the IWF only deals with child abuse content hosted on the ‘public’ internet and won’t affect that available on the so-called ‘dark web’. This private and often anonymous part of the internet is considered a haven for illegal activity, although it also has legitimate uses, such as whistle blowing and internet access in repressive regimes.

[Related story: Cybercrime warning over 'dark web’]