Craig Wright, the man who earlier this week claimed to be inventor of Bitcoin, has backed out of a commitment to present new proof that he is Satoshi Nakamoto.
With many unconvinced by the evidence so far provided to back up his claim, yesterday Wright said that he would transfer some bitcoins from "block 9" by using a private key understood to be known only to Satoshi.
However, the Australian academic and entrepreneur has now posted a new message on his website, entitled "I'm Sorry" and ending "goodbye".
"I believe that I could do this. I believed that I could put years of anonymity and hiding behind me. 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 has apologised to Bitcoin bigwigs Jon Matonis and Gavin Andresen, who were early backers of his claim to be the bitcoin inventor.
Andresen has since rowed back on his support, telling security researcher Dan Kaminsky: "It was a mistake to agree to publish my post before I saw his - I assumed his post would simply be a signed message anybody could easily verify."
"OF COURSE he should just publish a signed message or (equivalently) move some [bitcoin] through the key associated with an early block."
That will not now happen, but Wright says that Andresen and Matonis "were not deceived". However, he adds "I know that the world will never believe that now, I can only say I'm sorry."
For his part, Matonis appears to be sticking by Wright, tweeting: "There won't be an on-chain signing from early bitcoin blocks, but there also won't be another Satoshi."