Man has two guesses to unlock bitcoin worth $240m

Mr Thomas stored his bitcoins in a digital wallet and wrote the password on a piece of paper he has lost

We've all been there - brain fog makes us forget our password and after eight frantic attempts, we have just two left.

That's the situation for programmer Stefan Thomas but the stakes are higher than most - the forgotten password will let him unlock a hard drive containing $240m (£175m) worth of Bitcoin.

His plight, reported in the New York Times, has gone viral.

Ex-Facebook security head Alex Stamos has offered to help - for a 10% cut.

• Bitcoin tops $34,000 as record rally continues

• Cryptocurrency: Bitcoin hits three-year high as investors jump in

• Man searches for hard drive with £4m worth of bitcoins stored

Bitcoin has surged in value in recent months.

One bitcoin is currently worth $34,000.

But the cryptocurrency is volatile.

And experts are divided about whether it will continue to rise or crash.

Few dollars

Mr Thomas, who was born in Germany but lives in San Francisco, was given 7,002 bitcoins as payment for making a video explaining how cryptocurrency works more than a decade ago.

At the time, they were worth a few dollars each.

He stored them in an IronKey digital wallet on a hard drive.

And he wrote the password on a piece of paper he has lost.

Own bank

After 10 failed attempts, the password will encrypt itself, making the wallet impossible to access.

Perhaps unsurprisingly, the dilemma has put him off cryptocurrencies.

He told the New York Times: "The whole idea of being your own bank - let me put it this way, do you make your own shoes?"

"The reason we have banks is that we don't want to deal with all those things that banks do."

Locked out

Mr Stamos, who is now professor at the Stanford Internet Observatory, tweeted Mr Thomas: "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.

"I'll make it happen for 10%.

"Call me."

Mr Thomas would not be the first potential Bitcoin millionaire to be locked out of their fortune.

Currently, about $140bn worth of Bitcoin is lost or left in wallets that cannot be accessed, according to cryptocurrency-data company Chainanalysis.

And businesses helping retrieve digital currency receive multiple requests each day.

The New York Times article also references an entrepreneur who lost about 800 bitcoins when a colleague reformatted a laptop containing the private keys to his wallet.

And in 2013, a Welsh man desperately searched a landfill site after throwing away a computer hard drive containing 7,500 bitcoins.

At the time worth more than £4m, this would now be valued at more than £250m.