• by Laurie Sullivan  @lauriesullivan, August 10, 2015

Facebook, Google, Microsoft, Twitter, and Yahoo have teamed up with U.K. Web charity Internet Watch Foundation (IWF) to stop the spread of child abuse images online. A hash makes it easier to search and destroy. 

The IWF, which searches the Internet to find and remove abusive images, will provide the online industry a list of hashes embedded in child sexual abuse images to speed up the identification and removal of this type of content that might have been stored in their servers.

The process uses a unique identifier known as a "hash" or digital fingerprint. The system finds and identifies images more quickly to get them removed from the Internet. The charity shares the list with the some of the world's largest Internet companies, but plans to roll it out to others soon.

"There are billions of images on the Internet and by creating a digital fingerprint of a single image, you can pluck it out, like finding a needle in a haystack," the IWF said in a statement released Monday.

The IWF Hash List is a list of digital fingerprints of child sexual abuse images, which have been assessed by IWF analysts. The list of digital fingerprints is used by licensed IWF members to identify child sexual abuse images on their services. It is also used to prevent people from sharing or uploading these images.

The major Internet companies have made strides to prevent these images from being stored and shared on their respective networks, but now they will get help from the IWF.  The hash makes it easier for those using the list to find and delete the images before they are shared.

The IWF will automatically begin creating three types of hashes to meet the needs of the online industry. It will create PhotoDNA -- technology developed by Microsoft -- as well as MD5 and SHA-1 hashes. Companies use these tags to upload, store and search for images; as well as to filter and host services; social media and chat; data centers; and connectivity services.

Today, the IWF only can provide a hash for still images, but continues to work with member companies to trial video hashing software.