The whistleblower behind the Scorpene document leak will hand over the disk containing thousands of pages of data detailing the Indian submarine's stealth and warfare capabilities, to the Australian government on 29 August, The Australian newspaper said on 27 August.
It said that the identity of the unnamed whistleblower is already known to the Australian authorities.
The weekend edition of the newspaper said that neither France nor India knew about the leak till Monday afternoon when it sought a comment from French firm DCNS.
The paper said that the whistleblower wants Australia to know that its future submarine partner, France, has already lost control over secret data on India's new submarines.
His hope is that this will spur the Turnbull government and DCNS to step up security to ensure Australia's 50 billion dollar submarine project does not suffer the same fate, it said.
"He has not broken any law and the authorities know who he is. He plans to surrender the disk to the government on Monday," the newspaper said.
The newspaper said the story behind this leak may be more of incompetence than espionage, more Austin Powers than James Bond.
The Weekend Australian has been told by sources that the data was removed from DCNS in Paris in 2011 by a former French Navy officer who quit the service in the early 1970s and worked for French defence companies for more than 30 years before becoming a subcontractor to DCNS.
Sources say they believe this subcontractor somehow copied the sensitive data from DCNS in France and, along with a French colleague, took it to a Southeast Asian country. If so, he broke the law and may face prosecution, the paper said.
The two men worked in that Southeast Asian country carrying out unclassified naval defence work.
The speculation is that the data on Scorpene was removed to serve as a reference guide for the former naval officer's new job, but it is unclear why anyone would risk breaking the law by taking classified data for such a purpose.
The two men are then said to have the fallen out with their employer, a private company run by a Western businessman.
They were sacked and refused re-entry to their building. At least one of the men asked to retrieve the data on Scorpene but they were refused and the company - possibly not knowing the significance of the data - held on to it, the newspaper said.
The secret data was then sent to the company's head office in Singapore, where the company's IT chief - again probably not knowing its significance - tried to load it on an internet server for the person in Sydney who was slated to replace the two sacked French workers.
The data was placed on a server on April 18, 2013, and it was then that it was dangerously vulnerable to hacking or interception by a foreign intelligence service.
It is not known whether the data stayed on this server for a few days or for a year. It is not known if any foreign intelligence service obtained it during this time, the paper said.
Unable to send such a large file over the net and not knowing the significance of the data, the Singapore company sent it on a data disk by regular post to Sydney.
When the recipient, who was experienced in defence issues, opened the file on his home computer he was stunned.
He was expecting to read notes on a low-level naval programme, but before him lay the secret capabilities of the new Indian submarine fleet, the report said.
The data was not encrypted so he transferred it to an encrypted disk. That evening the man wiped the old disk with special software, grabbed a hammer and smashed it to pieces in his backyard.
He placed the new encrypted disk in a locked filing cabinet in his office and there it remained for more than two years, before he decided to show it to the The Australian, the report said.