The first quantum computer to break encryption is now surprisingly shut down

A quantum computer capable of breaking the encryption that secures the Internet is just around the corner. Surprising revelations from two research teams show how this could be, one suggesting that the current largest quantum machines are already more than half the required size.

Both studies relate to an encryption technique built around the elliptic curve discrete logarithm problem (ECDLP). The details of how this mathematical problem is solved made it a good candidate for encrypting data and it became widely adopted to secure a lot of Internet communications, including bank transactions and almost every major cryptocurrency, including Bitcoin.

Elliptic curve-based encryption is extremely difficult for conventional computers to crack, but researchers since the 1990s have known that quantum computers won’t have as much trouble. However, building a quantum computer large enough was an engineering impossibility, so it seemed a distant concern.

In recent years, both theory and engineering have advanced at staggering speed, greatly shortening the timeline. On the theory front, researchers have adapted quantum hacking algorithms to reduce the actual amount of quantum computing power required. For example, in 2019, the best estimate of the size needed to crack a related encryption method called RSA-2048 was 20 million qubits – a qubit is the quantum equivalent of a conventional computer bit. In February this year, this number dropped to just 100,000 cubits.

Furthermore, in 2019, state-of-the-art quantum computers barely crossed 50 qubits. Today’s largest quantum computers have more than 1000 qubits and the largest qubit array – not actually used for computations yet – has 6100 of them.

Now, dolev bluestein The firm Oratomic and their team believe that ECDLP can only reach a machine with 10,000 qubits. While this decryption process would take years of runtime for a quantum computer, Ryan Babbash and his colleagues at Google’s quantum research branch have separately charted how 500,000 qubits could do the same in just 9 minutes.

“Today is an important day for quantum computing and cryptography,” justin drake At the Ethereum Foundation, who collaborated with Google researchers, written on x.

Bluvstein and his colleagues based their calculations on qubits made of extremely cold atoms controlled by lasers. Such qubits can be interconnected in many ways, and this greater interconnectivity is partly responsible for the lower qubit requirement.

Bluvstein says it might be possible to build an array of 10,000 ultracold qubits within a year, but the real challenge will be controlling them well enough and making them work fast enough. There is no shortcut like connecting multiple existing machines, because qubits must be able to interact properly with each other.

Bluvstein thinks a capable machine will not be ready until the end of the decade. “There’s still a lot of progress to be made,” he says, “but it’s starting to become something that people can actually imagine building.”

crypto concerns

The Google team reached its conclusions based on a different type of quantum computer made of superconducting circuits, which is largely considered the more mature technology and the one Google has been most supportive of.

The researchers declined to comment publicly on the work, but in their paper they wrote that “resource estimates can be substantially reduced by making more aggressive assumptions about hardware capabilities”, suggesting that the 500,000-qubit estimate is conservative. Notably, the researchers have chosen to omit full details of their decryption algorithm, citing security concerns.

He also wrote that such quantum computers could be used to intercept cryptocurrency transactions and redirect funds – essentially stealing them – in the brief period before they are recorded.

Bitcoin certainly looks more vulnerable to a quantum attack than previously known, looking at two studies scott aronson At the University of Texas at Austin.

Stefano Gogioso The University of Oxford says both types of quantum computers face significant engineering challenges before any results can be implemented in practice, particularly the ultracold-atom approach, which is a largely unproven technology. But there is reason to worry about the security of our digital world, he says.

Some internet browsers already offer encryption impervious to quantum attacks, so-called post-quantum encryption (PQC), and traditional banks may be able to thwart quantum hackers once they are attacked, but Gogioso says a very decentralized system of cryptocurrencies would be much more vulnerable. Google recently urged migration to PQC by 2029, which Gogioso says seems even more urgent.

“That’s why we started the PQC standardization project a decade ago,” says dustin moody At the National Institute of Standards and Technology (NIST) in Maryland. “We have always known that as quantum hardware improves, the algorithms will also improve.”

NIST has selected several PQC algorithms that could become security standards in a future filled with practical quantum computers, and the US federal government is aiming to use them by 2035. But Moody’s says organizations should begin their transition as soon as possible. “These documents reinforce the idea that migration potential is limited and the time to act is now,” he says.