--- Date: Tue, 26 Mar 2002 13:08:08 +1100 From: Nathan Cochrane <ncochraneat_private> Organization: The Age newspaper To: Dave Farber <daveat_private>, Declan McCullagh <declanat_private> Subject: Australian Government releases content filtering survey in time for Philadelphia trial Hi Dave, Declan Call it kismet, providence or good timing, but the Australian Government has released a 90 page report into the effectiveness of censorware as the CIPA goes to trial in Philadelphia. http://www.interesting-people.org/archives/interesting-people/200203/msg00184.html http://www.politechbot.com/p-03297.html The report was commissioned by the Australian Broadcasting Authority (www.aba.gov.au), which is responsible for censoring the Internet in this country, and conducted by the Commonwealth Scientific and Industrial Research Organisation (www.csiro.gov.au). http://www.aba.gov.au/internet/research/filtereffectiveness.pdf "Effectiveness of Internet Filtering Software Products" gives a basic background to the problems of censoring Internet content. It then addresses the different approaches vendors use, such as inclusion/exclusion, content, source and image filtering. It finishes by reviewing 14 products and services including Cyber Patrol 5.0, AOL Parental Control 6.0 and Net Nanny 4.0. The report doesn't take a moral or ethical stance, but outlines what can be achieved with the technology available. Some highlights from the report: "While it is technically feasible to block access to all undesirable Internet content, no Internet blocking or filtering scheme will ever be 100% effective, or resist a determined and informed attacker, but many of them will be perfectly adequate in normal use." "A completely safe Internet may well be a very restricted Internet, especially when new types of content and new distribution technologies emerge." "Many filtering products are based on lists of Web sites that are supplied by their vendor. These lists are expensive to produce, as they have to be compiled by having people examine and classify Internet content, and as a result these lists are often closely held proprietary information. The secret nature of these lists can make it difficult to know just what content is being blocked and for what purpose. "These lists also reflect the values of the organisations and people who compile them, and may not reflect the values of Australian society as a whole. Some Internet activists (Peacefire) complain that commercial filtering products reflect US-based conservative and religious values, and as such may not reflect the more liberal values held by Australian society. Cultures differ considerably in their concepts of acceptable content and filtering products really have to customise their lists to meet local cultural norms." "Content filtering is a difficult problem. Even text-based filtering requires some ability to determine context (and meaning) for words they discover. Early products were infamous for simplistic filtering, with the blocking of "breast" cancer content being the most quoted example. Filtering products have improved since those early days but the task is still very difficult and moderately high error rates can be expected. Filtering out non-textual information, such as photographs or video, is much more difficult and problematic." "All filtering technologies are fallible, and the more effective they are, the more they risk intruding on general Internet usage. Products have to strike a balance between filtering out undesirable content, and allowing access to (possibly unknown) useful content. The white list products are the most effective because they are the most restrictive and constrain users to a very small part of the Internet." "Much attention is paid to filtering Web pages but undesirable content can be found in many places on the Internet, including newsgroups and file servers. Some of the more tightly filtered Internet services, such as some of those designed for the educational market, resolve this problem by completely blocking access to all Internet services other than the Web and e-mail. This approach is certainly safe, but would be unacceptable for the general Australian community and so these other sources may have to be filtered as well." "An emerging problem with filtering Web traffic through the use of server-side filters is the rapidly increasing use of the Web's protocol (HTTP) and port (80) for other purposes, such as e-commerce and Web Services. Filtering all HTTP traffic could result in degraded performance for major applications, rather than just slowing down interactive Web browsing." ********************************************************************************* This email and any files transmitted with it may be legally privileged and confidential. 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