Dotcom told reporters this afternoon that he would show that Mr Key knew about him before the police raids on his Coatesville home in 2012 -- contrary to Mr Key's public statements.
With assistance from Mr Greenwald and possibly other guests, he said he would also reveal sensitive information about New Zealand spying agencies' role in global surveillance.
Prime Minister John Key said today he was not losing sleep about Dotcom's "stunt".
"If he seriously has some information, then he should feel free to put that in the public domain and I'll be more than happy to put my side of events."
Mr Key said the internet Party boss was an attention-seeker and had been watching too much of the TV show House of Cards.
Dotcom made the comments today at the latest stop on the internet-Mana party's national roadshow in Auckland. The upbeat gathering was attended by around 300 supporters in a packed Kelston Community Hall.
The party's candidates emphasised internet Mana's activist roots, with both Mana Party leader Hone Harawira and Dotcom speaking proudly of their brushes with the law.
Mr Harawira said he was blown away that he was the only politician since 1951 to have been arrested while a sitting MP.
"Why are we electing people to Parliament who haven't got the courage to stand up for the things that constituents believe?"
The most recent Herald DigiPoll survey, published today, showed internet Mana's support had risen to 2.2 per cent, which would get them three MPs in Parliament if Mr Harawira won his seat in Te Tai Tokerau.
Dotcom, who has put at least $3 million into internet Mana, was introduced as "the reason we have speakers today and not a three-stringed guitar".
He addressed the scepticism about his political motives, saying he formed the party as a gesture of gratitude for New Zealanders' support when he was arrested.
Dotcom spoke openly about his background as a computer hacker, claiming he had broken into the IT networks of Nasa, Citibank, and a credit rating agency before being offered a $1 million government loan to form an internet security business.