"There's no ambiguity. No middle ground. I'm right. He's wrong," Mr Key told reporters today.
Mr Key said Cabinet signed off a proposal for the GCSB to investigate a business case for widespread cyber protection of New Zealand entities, but he personally stopped the work in March last year because he thought it was a step too far.
"In the end, that never even got to a business case."
Mr Key said he would declassify documents to show the proposal to look at the business case, the decision to rescind that, and what the current programme is -- but he would wait until after tomorrow night's event.
"It's incumbent on him [Greenwald] to release his documents. He releases things, we'll prove that we're right."
The proposal for a business case was during an internal review of the GCSB and was sparked by cyber attacks on two New Zealand private companies, around March 2012.
"It created mayhem. It was very expensive, very significant, it put New Zealand at risk," Mr Key said, declining to name the companies.
The two companies have since signed up for GCSB cyber-protection, which is a two stage process that requires a warrant to look at emails, Mr Key said.
"This is about the protection of critical information or secrets that these companies might have. It's never been about looking at secrets. It's very much about, in a non-invasive way, making sure that information or emails coming into the company are analysed for any digital signatures that would indicate a virus or malware.
"At a Government agency level, whether it's Treasury or Mfat or the Reserve Bank or any of those organisations, there may not be a week that goes by when they are not subjected to some threat."
He stood by the GCSB work to gather foreign intelligence and share it with Five Eyes partners the US, the UK, Canada and Australia.
"What they do is long-standing, it's been over successive Governments, it's been to protect New Zealanders' interests and their rights."
Mr Key stepped up his attacks on Dotcom and Greenwald, saying Dotcom didn't care about New Zealand and repeatedly called Greenwald a Dotcom "henchman".
The timing of the event was to inflict maximum political damage, and if Greenwald had turned up with his claims six months ago, "we could have had a discussion with him, and we might even have a modicum of respect for his journalistic capability".
"But when he joins the Dotcom train, rolls into town five days before an election, with his expenses paid for by Kim Dotcom, every New Zealander should understand what this is about."
He said Dotcom only cared about his extradition case.
"He is a man who will do anything, say anything, and pay anyone to save Dotcom's butt."
