A Quantum Computing graduate student calculated how big a quantum computer would need to be to crack Bitcoin's cryptographic algorithm.
Mark Webber and colleagues at the Ion Quantum Technology Group at the University of Sussex concluded that quantum computers need to be a million times larger than they currently are before they can crack Bitcoin's SHA-256 algorithm – an algorithm previously published by the Security Agency. U.S. National (or NSA) in the early 2000s.
The Ion Quantum Technology Group conducts research on quantum computing and quantum microwave sensors.
It is well known that Bitcoin's encryption technology is so strong that attackers would need to commandeer 51% of the combined computing power of Bitcoin's global network to compromise its "immutable" record.
But every transaction in Bitcoin's ledger is signed by a cryptographic key (a random series of letters and numbers), which is vulnerable for a finite period of time.
With enough computing power (or a powerful enough quantum computer), this key can be deciphered.
Webber estimates that if an attacker had a ten-minute window to decipher the key, they would need a quantum computer with 1.9 billion qubits. If the key is vulnerable for 24 hours, that number drops to 13 million qubits.
Can Quantum Computers Threaten Bitcoin?
Given that the largest semiconductor quantum computer on the market is IBM's 127-qubit model, it doesn't seem like quantum computers are a security threat to crypto.
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 halved.
Basically, as time goes on, we will have more features at a lower price.
In the world of quantum computing, this law has been replaced by Neven's Law, which dictates that quantum computing power undergoes "double exponential growth relative to conventional computing."
For perspective purposes, double exponential growth would allow notebooks and smartphones to exist in 1975.
So, if quantum computer hardware grows exponentially faster than ordinary transistor circuits then, theoretically, one day it could crack Bitcoin's code.
It will just be a matter of when that happens. Webber believes this could be possible a decade from now.
*Translated and edited by Daniela Pereira do Nascimento with permission from Decrypt.co.
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