The Australian government's cyber security agency has confirmed it pressured organisers of a major conference to scrap two speakers a week out from the event.
Head of the Australian Signals Directorate's Australian Cyber Security Centre Rachel Noble confirmed she asked CyberCon 2019 organisers to withdraw invitations for Thomas Drake and Suelette Dreyfus to speak at the event.
Mr Drake was a former senior executive of the US National Security Agency. He became the first American charged with espionage in nearly 40 years in 2010 for leaking details of mass surveillance programs. His case inspired Edward Snowden to go public about the NSA's spying in 2013, due to the reprisals Mr Drake suffered.
Dr Dreyfus is a Melbourne University lecturer whose field of research includes digital security and privacy and the impact of technology on whistleblowing.
Ms Noble told Senate estimates on Wednesday night she asked organisers to pull the pin, in response to a proposal for Mr Drake and Dr Dreyfus to appear on a panel with Mr Snowden via video-link.
"At that point my judgement was based on I guess all of those speakers, that they are known public advocates for unauthorised disclosure or the leaking of classified information outside of legitimate whistleblowing or lawful whistleblowing schemes," Ms Noble said.
"My concern was that firstly those presentations weren't consistent with the objectives of the conference which was actually about cyber security and helping Australians raise their awareness and technical knowledge about cyber security issues and secondly my concern that there was a risk that those speakers would express views that are inconsistent with Australian government laws and our processes and our values."
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But Dr Dreyfus said neither she or Mr Drake were going to speak about whistleblowing.
"Ironically, Mr Drake was speaking about 'The Golden Age of Surveillance'. I was speaking about the technology of secure digital drop boxes which are being used as an anti-corruption tool in Europe - including by government agencies - to improve internal security," Dr Dreyfus said.
"[The centre] knew full well these were our talk topics because they had seen the final slides and abstracts -yet they still removed us from the speakers' list.
"Here's an Australian value: calling out bad behaviour by our federal government."
Dr Dreyfus said the centre's admission "suggests a deeper, more pervasive approach to shutting down public discussion".
"Silence the academic from presenting research at a conference, gag the journalist from writing the story, raid the publisher who dares to run the news. There's an emerging pattern," she said.
"Whistleblowers should be properly protected when they reveal war crimes, corruption or other acts of illegality. Every major media organisation in Australia who ran blacked out their news pages as part of the 'Your Right to Know' blitz this week also wants better laws to protect whistleblowers; it is one of their six planks that the current law be changed."
Mr Drake told The Guardian earlier this month the cancellation of his speaking invitation was "Orwellian".
Meanwhile, Defence Minister Linda Reynolds has also weighed in on reports that intelligence agencies determined China was responsible for a cyber-attack on the Australian parliament and three political parties before the May election.
Questioned about the government's decision not to publicly name China as the source of the attack, Senator Reynolds said: "Public attribution is just one of the many responses Australia has in its toolkit."
"Not all of Australia's responses to cyber incidents will be made public," Senator Reynolds said.
"The government publicly attributes when it's in the nation's interest to do so, so it is very much a case by case basis."