If Stefan Thomas fails and burns through his final two of 10 attempts, he will lose 7002 Bitcoin, currently worth an eye-watering and lifechanging $303 million.
The forgotten password which is keeping Mr Thomas awake at night would let him unlock a small hard drive, known as an IronKey.
The IronKey contains the critical private keys to Mr Thomas’ digital wallet, where the Bitcoin fortune is locked up.
If Mr Thomas makes 10 failed IronKey password attempts, the hard drive will seize up and encrypt everything for eternity.
“I would just lay in bed and think about it,” Mr Thomas told The Times.
“Then I would go to the computer with some new strategy, and it wouldn’t work, and I would be desperate again.”
Alex Stamos, an internet security expert at Stanford Internet Observatory, claimed he can crack the password within six months.
His price? Mr Stamos wants a 10 per cent cut (roughly $30 million) of the fortune.
“Um, for $220m in locked-up bitcoin, you don’t make 10 password guesses but take it to professionals to buy 20 IronKeys and spend six months finding a side-channel or uncapping,” Mr Stomas said on Twitter.
“I’ll make it happen for 10%. Call me.”
Mr Thomas was paid the Bitcoin for making a video about how the cryptocurrency worked, back when it was worth around $5 a coin.
Last week, on the back of a record-breaking run, Bitcoin was trading at more than US$40,000.
Perhaps the best-known case of anyone losing their Bitcoin fortune was James Howells, a Welsh IT worker, who in 2013 unintentionally threw 7500 Bitcoin in a landfill.
Mr Howells’ Bitcoin would also be worth more than a quarter-billion-dollars on today’s rate.
He tossed his hard drive, where his Bitcoin private keys were stored, into a rubbish bin which was dumped at Newport, South Wales.
“After I had stopped mining, the laptop I had used was broken into parts and sold on eBay. However, I kept the hard drive in a drawer at home knowing it contained my Bitcoin private keys, so that if Bitcoin did become valuable one day I would still have the coins I had mined,” he told the Telegraph.
Bitcoin first surpassed the US$20,000 ($25,950) level in mid-December and soared above US$30,000 ($38,920) earlier this month – a huge rebound from a low of just above US$4000 ($5190) as the COVID-19 outbreak sent global financial assets plummeting last spring.
Even with the drops over the weekend and Monday, Bitcoin is still up more than 10 per cent already in 2021 – and it has soared about 300 per cent in the past 12 months.