A Bitcoin wallet with nearly $700 million is up for grabs — but anyone intending to be a “crypto thief” and nab it will have to crack the password first.

Crypto Twitter user Alon Gal has put out a call to his 29,900 followers for solutions on how to gain access to 69370.22 Bitcoin (BTC), worth roughly $695.4 million as of this writing. According to the Sept. 8 post from Gal, the wallet has been passed between hackers for the past two years without success at determining the password.

Source: Twitter

Blockchain records show transactions associated with the wallet address began in April 2013. Many online forums like All Private Keys offer members of the crypto community a chance to crack Bitcoin Core wallet.dat files with lost passwords for a share of the remaining balance. 

“I have the wallet,” Gal said. “Google, hook me up with a quantum computer please.”

This raises an interesting question — using a quantum computer, what would be the chance someone could gain access to a random wallet with a lost password, even with a $695 million motivation?

Advancements in quantum computing have been areas of contention for cryptocurrency proponents for some time, as many believe the machines could undermine the security of the Bitcoin blockchain.

Experts, however, are divided on the idea. While the very primitive present-day quantum computers cannot break blockchains and their underlying cryptography, larger ones on the horizon might have that capability.

As recently as June, scientists in China were able to exchange an encryption key at a distance of 1,120 kilometers using quantum entanglement, exceeding the previous best attempt by 1,000 kilometers. Further advancements in the technology could potentially mean users would be able to authorize transactions outside of the Internet.

In terms of lost passwords, the technology would have the ability to go through more permutations than the best machines today to find the unencrypted passwords or even to reverse a hash.

Last year, ex-Bitcoin Core developer Peter Todd called Google’s “quantum superiority” feat — a computer which solved an equation which would otherwise take 10,000 years in just 3 minutes 20 seconds — as “a primitive type of quantum computing that is nowhere near breaking cryptography.”

However, others including Deloitte aren’t so sure. The accounting firm’s website states that current technology in quantum computing makes 25% of all Bitcoin in circulation vulnerable to attack. If enough coins were stolen, the market could potentially crash, undermining confidence in cryptocurrency.

“Even if everyone takes the same protection measures, quantum computers might eventually become so fast that they will undermine the Bitcoin transaction process,” the firm stated. “In this case the security of the Bitcoin blockchain will be fundamentally broken.”