The Australian Federal Police has no gauge for the success of a voluntary internet filtering trial in its first months of operation apart from controversial redirect statistics provided by Telstra.
Neil Gaughan, head of the AFP's High Tech Crime Operations Centre, told a Senate Estimates hearing last week that Telstra had made a total of 84,000 redirections from sites believed to contain child abuse material to a block page maintained by Interpol.
Gaughan told Greens senator Scott Ludlam last week that Telstra was the only company to offer the statistic.
But iTnews has learned that other ISPs to participate in the filter trial had either not been asked to provide statistics or are technically unable to.
An Optus spokesman said the telco had not provided any redirection statistics to the AFP as it had not been asked.
Mark Riley, chief technical officer of ContentKeeper Technologies - which provides the content filtering hardware and software used by trial ISP CyberOne - said information regarding redirections to the Interpol block page is completely transitive.
The ContentKeeper hardware had been configured to operate in an 'Interpol mode' when redirecting users based on information in the list, disallowing even systems engineers at the service provider from accessing any identifying information.
"Obviously if someone was to take out a court order obviously we would make changes in the system but not retrospectively, so for the moment the system is completely anonymous in its main operation," he said.
"If we don't keep the information, it can't be requested."
Managing director of CyberOne, Maciej Mirkut, could not be reached for comment.
The redirect debate
Telstra's redirect figures have been criticised by many, including VoIP and network engineer Michael Wyres, for failing to take into account how many actual users visited offending sites.
The number, he said, could be blown out by multiple hits to a website by the same user, or the number of hits involved in a website loading in the first place.
Other telecommunications experts characterised the figure cited by the AFP as "odd".
"The data provided by Telstra is purely a count of redirection triggers which occurs using the Interpol 'worst of' list," an AFP spokeswoman said.
"It does not specify which particular site was being sought, nor does it identify users in any manner."
Telstra refused to clarify the number as it was "not commenting publicly on the matter".
An AFP spokeswoman said Police are unlikely to obligate internet service providers to provide the statistics in future.
"The provision of (non identifying) statistical data by participating ISP's is not compulsory," the spokeswoman said.
"Due to differing infrastructure operated by the ISP's in some cases, it may not be technically possible or cost prohibitive to instigate.
"It is a decision for each individual ISP as to whether they provide statistical data in the future."
The filter, launched in July in lieu of a wider filter covering refused classification material, has been rolled out by Telstra, Optus and CyberOne across select users.
Each domain is viewed and affirmed by at least two officers in separate, participating countries.
The "worst of" list, also maintained by Interpol, is updated weekly with domains depicting real children younger than 13 years of age in an exploitative context.
Further ISPs have indicated interest in joining the "open-ended trial", according to the Australian Federal Police (AFP).