Why Internet Censorship Does Not Work - More Information: Green Dam Filtering Software


The Chinese Government used an image-scanning technique to aid their censorship efforts. The attempt came about partially as the result of site operators posting pornographic images on pages with neutral text (so that the filter wouldn’t pick up on ‘banned’ phrases).


The software scans images to try and ascertain how much skin was on display in the image, although it correctly identifies some images it suffers from a number of technical issues;

  • It does not recognise images of people with darker skin (or in the case of cartoons – red skin)

  • Some very graphic sexual acts are missed because not much skin is visible


It also generates a lot of false positives, which led to the automatic filtering of a lot of non-adult content including;

  • Images of the cartoon cat Garfield

  • Images of Roast Pork

  • Images of Johnny Depp’s face


Green Dam also includes a content-filter, which drew scepticism about the Chinese Government’s claim that it was to “protect the growth of young people” when it was discovered that 85% of the pre-programmed keywords were related to political matters and just 15% related to pornography.


Not only does Green Dam filter internet use, but also monitors applications such as Microsoft Word for ‘inappropriate’ phrases. Should something inappropriate be detected (in the browser or otherwise) all windows are closed without notifying the user.


Multiple security vulnerabilities have also been found, allowing attackers to access personal data, remotely compromise (‘hack’) or use the machine to send SPAM.


The filter is actually a piece of software called Green Dam Youth Escort, which was originally mandated on all new PC’s by the Chinese Government. However, it was then made voluntary and the deadline has repeatedly slipped.


At time of writing, the company behind Green Dam is on the brink of collapse having received no further funding from the People’s Republic of China. It appears that the Chinese Government may have abandoned plans to use Green Dam in their censorship programme.