Bitcoin Could Be Cracked With Quantum Computers Within 10 Years

A quantum computing graduate student has calculated how big a quantum computer would need to be to crack Bitcoin's secure cryptographic algorithm

Mark Webber and his colleagues at the Ion Quantum Technology Group at the University of Sussex concluded that quantum computers would need to be a million times larger than current ones to crack Bitcoin's SHA-256 algorithm, an algorithm first published by the US National Security Agency (NSA) in the early 2000s.

The Ion Quantum Technology Group conducts research around quantum computing and quantum microwave sensors.

Conventional wisdom holds that Bitcoin's encryption technology is so strong that attackers need to commandeer 51% of the combined computing power of the global Bitcoin network to compromise its "immutable" ledger.

But every transaction on the Bitcoin ledger is assigned a cryptographic key - a random string of letters and numbers - that is vulnerable for a finite amount of time.

If you have enough computing power, or a powerful enough quantum computer, this key can be cracked.

Webber calculates that if an attacker has a ten-minute window to crack the key, he would need a quantum computer with 1.9 billion cubits. If the key is vulnerable for 24 hours, this figure drops to 13 million qubits.

Will quantum computers ever be able to crack Bitcoin?

Given that the largest superconducting quantum computer on the market is IBM's 127-qubit model, it does not appear that quantum computers pose much of a threat to the security of cryptocurrencies.

In traditional computing, Moore's Law dictates that the number of transistors on a microchip doubles every two years, while the cost of computers is cut in half.

In essence: as time goes on, we get more profit for less money.

In the world of quantum computing, this law has been superseded by Neven's Law, which dictates that quantum computing power experiences "double exponential growth relative to conventional computing."

To put it in perspective, doubly exponential growth would have given us laptops and smartphones in 1975.

So, if quantum computing hardware improves exponentially faster than normal transistor circuits, then it could theoretically one day crack the Bitcoin code.

It's just a matter of when.