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Currently, brute forcing a Bitcoin private key is very impossible—but new technologies may change that.
A Bitcoin private key is being brute-forced.
In principle, this is similar to a brute force assault on any normal password. Before identifying a private key combination, an exhaustive search of potential combinations is performed.
Brute force assaults on a Bitcoin private key, on the other hand, are mathematically impossible.
A private key is a number between one and two thousand two hundred sixty-sixty-sixty-sixty-sixty-s That implies a brute force assault must look for the correct number between one and 115 quadrillion. To put it in context, that’s a 78-digit figure that’s thought to be more than the entire number of atoms in the universe.
If you think a brute force strike on that magnitude is unfeasible, you’re right. However, new technologies may be on the horizon that may make the challenge less daunting—an unsettling possibility for bitcoin holders.
Could quantum computing break Bitcoin?
The crypto world has been eyeing quantum computing nervously for some time now. The development of the technology is proceeding at a pace, with tech giants like Google and IBM competing with nascent start-ups like PsiQuantum. The likes of Goldman Sachs and JP Morgan have invested in researching the technology, too; no surprise, then, that the market for quantum computing is expected to hit $64 billion by 2030.
But what exactly do quantum computers do, and how do they function?
Quantum computing is the use of quantum phenomena such as superpositions to accomplish computer tasks; in other words, quantum computers can conduct probabilistic computations. As a result, rather of working with 1s and 0s like traditional computers, quantum computers can handle exponentially more data.
So, should cryptocurrency owners be concerned? Can quantum computers shorten the time it takes to crack our encryption keys?
In October 2019, Ethereum co-founder Vitalik Buterin tweeted about quantum computing. He was not convinced that the crypto business should be concerned—yet. “My one-sentence impression of recent quantum supremacy stuff so far is that it is to real quantum computing what hydrogen bombs are to nuclear fusion,” he said.
With that said, there are some quantum computing minds that can unpack exactly what threats the crypto industry faces.
Andersen Cheng, CEO of Post-Quantum, a company providing information solutions against current and future threats, told Decrypt: “The general consensus for a commercially viable quantum computer is 10-20 years away. However, we are talking about a functional rather than a commercially available quantum computer. They are two entirely different things.”
A functional quantum computer, which Cheng described as “a Frankenstein monster created in a lab,” is five to 10 years away.
That begs the question: With the right means, are we set to watch private key secrecy fade away in the next decade?
Replacing private keys with a quantum computer
One method a quantum computer may jeopardise the security of bitcoin private keys is to replace them immediately, without having to take them from anyone’s wallet.
According to Cheng, some in the bitcoin world feel that signatures are already post-quantum computing. Even if it is, Cheng notes that “until a block is truly confirmed by ensuring previous blocks are truly immutable, there is still an ephemeral period in which one can replicate the private key to begin signing unauthorised transactions.”
Cheng stated that once this occurs, trust is lost. “You can’t tell if that Bitcoin transfer you just made came from your true private key or a private key duplicated by a quantum computer without even touching your wallet,” he added.
Of course, it’s also worth considering why someone would want to do this in bulk. The sector will no longer be able to claim that it is protected by impenetrable blockchain technology the moment private keys fall to quantum computing, and the value of crypto assets will drop as a result.
Who would desire such a thing? No one, but that doesn’t imply the threat presented by quantum computing goes away.
Quantum computing is making waves
In February 2021, Microsoft announced the opening of its Azure Quantum service, which brings quantum computing to Microsoft’s customers. The service’s quantum computers use a design called an ion trap, which users electronically charged atoms to store and process information.
Those atoms are called qubits, and most quantum computers—to date—have only had a few dozen worth. In Australia, researchers publishing in the Nature Electronics journal are pushing the needle forward even further, potentially opening the door to quantum computers that make use of thousands of qubits. Quantum computing on steroids.
And quantum computers could be coming to a desktop near you; Shenzhen-based computer manufacturer SpinQ is reportedly working on a desktop quantum computer that could cost as little as $5,000. Targeted for release in the fourth quarter of 2021, the 2-qubit device is aimed at schools and colleges in China.
At the start of February 2021, a group of quantum computing experts raised concerns about the moral ramifications of this technology. “Whenever we have a new computing power, there is potential for benefit of humanity, [but] you can imagine ways that it would also hurt people,” said John Martinis, professor of physics at University of California, Santa Barbara.
And the consequences could span well beyond the crypto industry, even with concerns about accelerated DNA manipulation coming to the fore.
Cheng employs a fairly simple acid test for people who are sceptical that quantum computing would fundamentally harm Bitcoin. “I asked them if they are willing to convert all of their real fiat assets, such as USD, GBP, or even their house, into Bitcoin or Ether and go through the quantum timeline,” he added. “To date, no one has informed me that they will.”
Cyber dangers have a habit of sneaking up on people. Prior to Stuxnet, little attention was paid to supply chain vulnerabilities, until it was too late—at least for Iran.
It may not be time to be concerned about quantum computers stealing your private keys, but it makes sensible to prepare for tomorrow’s dangers now.