Bitcoin creator Satoshi Nakamoto appears to have received a hacking attack against at least some of his online accounts, with the hacker offering to sell the anonymous developer’s personal information for 25BTC, or around £7,000 ($11,000).

A post on anonymous text sharing site Pastebin offered to provide the documents, which potentially include information about the famously secretive developer’s real identity, if 25BTC was sent to a particular bitcoin address. No time limit was given, but as of Tuesday the address has received just 1.5BTC.

An administrator of the semi-official Bitcoin Talk forum, Michael Marquardt, posted on Monday night that he had received an email from Nakamoto’s old address, “not spoofed in any way”, that made him certain the account was compromised.

“It seems very likely that either Satoshi’s email account in particular or gmx.com in general was compromised, and the email account is now under the control of someone else,” Marquardt wrote under his username, theymos. “Perhaps satoshin@gmx.com expired and then someone else registered it.”

Shortly after Marquardt’s post, “Nakamoto” posted on the Ning messageboard, one of the first places the real Nakamoto announced the creation of Bitcoin. Using the same forum account to append a comment to that announcement, the apparent hacker warned Satoshi that his details were for sale.

“Dear Satoshi,” the message read. “Your dox, passwords and IP addresses are being sold on the darknet. Apparently you didn’t configure Tor properly and your IP leaked when you used your email account sometime in 2010. You are not safe. You need to get out of where you are as soon as possible before these people harm you. Thank you for inventing Bitcoin.”

An email from the Guardian to the hacked email address bounced back on Tuesday morning, suggesting that either the real Nakamoto, or a friendly party with access to the address, had closed down the account.

Nakamoto’s true identity is one of great secrets of the dark web. The developer appeared from nowhere in late 2008 with the proposal for Bitcoin, posted a flurry of comments over the next two years, and then gradually faded out of public view during 2010. Even his closest collaborators in the development of Bitcoin never met him (or her or them, although the name is male) or received a hint as to the true identity.

Over the years, a number of attempts to unmask Nakamoto have been made. Linguistic analysis of his published comments was used to name cryptocurrency pioneer and early bitcoin collaborator Nick Szabo as the developer, while Hal Finney, another early collaborator who died of MND in August 2014, had also been suggested.

The highest profile attempt to unmask Nakamoto came in March 2014, when American magazine Newsweek accused a 64-year-old Japanese-American man named Dorian Nakamoto – born as Satoshi Nakamoto – of being the pioneer. Dorian Nakamoto strenuously denied the claim, which largely rested on circumstantial evidence and an apparent doorstep confession, before giving a shambolic interview in which he referred to the currency as “bitcom” and plead with the press for privacy.