Australian businessman Craig Wright has backtracked on a promise to provide "extraordinary proof" he is the creator of Bitcoin, stating in a blog post he no longer has the "courage" to do so.
Wright, 45, told the BBC, The Economist, and GQ on Monday that he was Satoshi Nakamoto, the pseudonym used by the creator of the digital currency.
However, his declaration was widely questioned, with computer security experts labelling it a "scam" and The Economist calling on him to further substantiate his claim.
The Brisbane-born entrepreneur responded with a blog post on Tuesday, saying he would move some of the early Bitcoin in the coming days to prove he is Nakamoto.
"I will be posting a series of pieces that will lay the foundations for this extraordinary claim, which will include posting independently-verifiable documents and evidence addressing some of the false allegations that have been levelled," Wright wrote.
"I will present what I believe to be 'extraordinary proof' and ask only that it be independently validated."
But on Thursday, a post on his blog reversed his position.
"I'm sorry. I believed that I could do this. I believed that I could put the years of anonymity and hiding behind me," the post read.
"But, as the events of this week unfolded and I prepared to publish the proof of access to the earliest keys, I broke. I do not have the courage. I cannot."
Wright said his qualifications and character had been attacked and when those allegations were proven false, new allegations began.
"I know now that I am not strong enough for this," he wrote.
Wright said he hoped the "honour and credibility" of his supporters, particularly Bitcoin consultant Jon Matonis and lead developer Gavin Andresen, would not be "irreparably tainted by my actions".
"They were not deceived, but I know that the world will never believe that now. I can only say I'm sorry. And goodbye," Wright said.
Based on leaked transcripts of legal interviews and files, Gizmodo and Wired previously highlighted that there is evidence to suggest Wright, along with computer forensics analyst David Kleiman, who died in April 2013, are the men behind Satoshi Nakamoto, the creator of Bitcoin that has never been identified.
Wired claimed in its report that it obtained "the strongest evidence" yet that shows Wright is the man behind the identity of Satoshi Nakamoto. However, it also cited the leaked documents it acquired remain unverified, and quite possibly fake or an "elaborate hoax -- perhaps orchestrated by Wright himself", with some evidence later altered.
"Despite a massive trove of evidence, we still can't say with absolute certainty that the mystery is solved. But two possibilities outweigh all others: Either Wright invented Bitcoin, or he's a brilliant hoaxer who very badly wants us to believe he did," Wired wrote.
Meanwhile, Gizmodo obtained a transcript in which Wright tells the Australian Taxation Office (ATO) that he has been "running Bitcoin since 2009".
However, the claims made by Gizmodo and Wired of whether Wright is the creator of Bitcoin are true or not continues to be questioned by the Bitcoin community.
Based on Wright's LinkedIn profile -- which has since been removed -- it indicated he was involved in a number of Australian tech enterprises including holding the role of CEO at DeMorgan, a "pre-IPO Australian-listed company focused on alternative currency" that controls companies such as C01N, an electronic wallet and transaction processor based on the Bitcoin blockchain.
At the end of last year, Wright's home and office were allegedly raided by the Australian Federal Police (AFP) in relation to an ATO investigation.
AFP informed Reuters at the time that all officers' presence at the home was not associated with Bitcoins, but rather what they were doing there was just "clearing the house".
Around the same time, high performance computing firm SGI denied its involvement with Cloudcroft Supercomputers Australia, a supercomputer firm that was founded by Wright under his parent company DeMorgan.
In a letter featuring the SGI letterhead and the supposed signature of SGI APAC service director Greg McKeon, SGI acknowledged it would be assisting Cloudcroft Supercomputers Australia in the development of hyper-density machines and supercomputers.
"As a global leader in high performance solutions for computers, data analytics and data management, SGI considers Cloudcroft a worthy partner in the goal to accelerate time to discovery, innovation and profitability," the letter said.
The letter also highlighted the two companies previously worked together to build Cloudcroft's first supercomputer, Sukuriputo Okane.
Further evidence to suggest that Wright was the supposed owner of a supercomputer was highlighted in a Cloudcroft blog posted in December 2014, which indicated that Wright at the time had intentions to build "the biggest supercomputer cluster in Australia, with just under 5 petabytes", in time for the release of the Top 500 in June 2015.
However, Cassio Conceicao, SGI EVP and chief operating officer, told ZDNet at the time that despite this, SGI never had any contact with Cloudcroft or Wright.
"Cloudcroft has never been an SGI customer and SGI has no relationship with Cloudcroft CEO Craig Steven Wright," he said.
Conceicao added that SGI had no record of the C01N supercomputer being purchased or serviced by the firm. The C01N supercomputer, which was placed at number 17 on the list of the world's fastest supercomputer in November, is another supercomputer that Wright apparently owned. It was allegedly created when Wright merged C01N and Tulip Trading, Cloudcroft's supposed flagship supercomputer, into a single high performance computer.
"SGI has no record of the CO1N supercomputer ever being purchased or serviced from SGI, therefore SGI suspects it may have been purchased on the grey market," Conceicao said. "SGI does not operate, maintain, or provide any services for this supercomputer."
Nakamoto, who invented Bitcoin in 2008, is estimated to be sitting on a fortune of up to AU$601 million worth of the currency.