ISP filter technology tested in the Government's controversial pilot could not block "inappropriate" content without an unacceptable amount of over-blocking, a report by Enex Testlabs has found.
The long-awaited report, released by Communications Minister Stephen Conroy today, described how ISPs participating in the trial filtered content according to three lists - the ACMA blacklist, and two lists prepared by Enex Testlabs.
According to the report, all nine ISPs managed to block all of the URLs listed on the Australian Communications and Media Authority (ACMA) blacklist - albeit after some modifications were made to the filters.
"Initially, several participants experienced difficulty loading and blocking the complete ACMA blacklist," the report stated.
"Some of the filters needed adjustments to be made so that they could recognise URLs that were long and complex and included spaces. Others included colons, question marks and percentages.
"Some URLs were associated with more than one IP address and some URLs redirected the user to a second URL.
"Following consultations with the product vendors, all issues experienced with loading URLs contained on the ACMA blacklist were resolved," Enex said.
Can more be filtered?
Six of the nine participating ISPs - all of which are anonymous in the report - then filtered against two further lists prepared by Enex.
"The second and third lists were not known to the vendors," Enex said.
"They therefore also served as a check of the filter's ability to identify and block/pass relevant additional content."
One list contained content that "would likely be classified as MA15+, R18+ and X18+. A proportion of the content considered to be strong M was regarded as being close to the MA15+ classification, and was also included on the test list," the report said.
That material included URLs that could be categorised as "gambling", "adult", "lingerie/swimsuit", "profanity", "nudism" and "sex".
According to the report, all the filters blocked between 78.8 percent and 84.65 percent of this "inappropriate" material.
"These results represent an improved level of performance when compared to previous Enex testing, and suggest commercially available filtering products are increasingly effective at including additional categories of content on their filtering lists," the report found.
But any higher percentage of success here would likely come at the expense of "over-blocking" of innocuous material, Enex said.
Enex tested the potential for over-blocking using a third list of URLs across categories including animals, cooking, plants, computers, government and science.
"The content on this list, while innocuous, is also designed to potentially lead some filters into recording a false positive. For example, references to sperm whales and robin red breast," Enex said.
All filters in the trials blocked "less than 3.37 percent of innocuous content", the report found.
"This is still considered high," the report said.
"A ‘successful outcome', from a filter vendor perspective, of the second and third URL list tests would be a high percentage of blocking of URLs in list two, matched by a zero to low blocking of URLs in list three. Blocking rates of below two percent would be considered low."
None of the ISPs in the trials were able to register an over-blocking rate under this level. The lowest rate of over-blocking achieved was 2.44 percent.
ISPs offered cash to go beyond mandatory blocks
The results did not appear to discourage the Government from encouraging ISPs to go down the path of blocking more than just the ACMA blacklisted content.
Communications Minister Stephen Conroy today announced the availability of grants for ISPs prepared to block content beyond mandatory refused classification (RC) material.
He said that "ISPs will be encouraged to offer additional filtering services through the availability of Government assistance but this will not be mandatory.
"For those families that wish to have a wider range of material filtered, including possibly X18+ and gambling sites, the Government will establish a grants program to encourage ISPs to offer these services on a commercial and optional basis," he said.
"These additional filtering services will help parents to choose what they want filtered without having to download and install software to their home computers."