The new file is 20 times bigger than the batch of 77,000 secret US military documents about Afghanistan that WikiLeaks dumped onto the Web in Jul 2010.
The cryptanalysts said that encoding 'Insurance' is virtually impossible unless WikiLeaks releases the key used to encode the material.
"There's no way that anyone has any chance of figuring out what's in there," said cryptographer Paul Kocher.
That hasn't stopped bloggers and journalists from speculating. Some say the files could be the 15,000 or so intelligence reports which WikiLeaks says it's held back for inspecting.
Cryptographers also said that the file was likely to bring out some data, which the US government and others employ to mask some of their most sensitive data.
Kocher also stated, "the question is that whether is it a bluff or is it something more substantial?"