The Components of the Green Dam System (06/14/2009) How might you design such a system? The first line of defense would be based upon a list of banned URL's. The second line of defense would be based upon filtering by (1) text; (2) photos and (3) videos. Funny things happened along the way for the Green Dam system.
First, about the list of banned URL's in the first line of defense. The project called Green Dam Youth Escort is designed to protect minors from harmful information. What kinds of information are harmful? In the western world, it would be sex and violence. In China, politics may be added. So how do you get a list of harmful URL's? The Chinese know all about the list of harmful political URL's, but they don't know about much about the list of harmful sex-violence URL's. By definition, the sex-violence URL's must be registered/located outside of mainland China because they are banned in China. Where would Green Dam get such a list? Apparently, one solution is to steal it from someone who has such a list.
(PC Magazine) China's Filtering Software Contains Pirated Code