Cracking encryption with a quantum computer is now 10 times easier

The amount of quantum computing power required to break common data encryption techniques has been reduced tenfold. This makes the encryption method even more vulnerable to quantum computers, which may be able to reach a reduced size within ten years.

The RSA algorithm is one of the most widely used encryption algorithms, used for things like online banking and secure communications. It is based on the mathematical difficulty of finding which two prime numbers have been multiplied together to produce a very large number. Since the 1990s, scientists have known that this problem could be circumvented by using a quantum computer, but this possibility was considered theoretical because the size required for such a quantum computer was much larger than could be built.

This slowly began to change as researchers built larger quantum computers and the estimated size needed decreased. in 2019 Craig Gidney at Google Quantum AI, he co-authored a paper that reduced those requirements from 170 million to 20 million quantum bits, or qubits. And in 2025, Gidney devised a way to reduce that number to less than a million qubits. Now, Paul Webster at Iceberg Quantum in Australia and his colleagues managed to reduce this number even further to around 100,000 qubits.

The researchers’ study builds on Gidney’s work to improve the algorithms, but suggests that a different scheme called qLDPC code is used to connect and arrange the qubits. In past schemes, qubits can only interact with their nearest neighbors, but the qLDPC code means they can interact with qubits that are further away. This approach increases connectivity and effectively increases the information density in a quantum computer.

Given this connectivity, the team estimated that for 98,000 superconducting qubits, like those currently produced by IBM and Google, it would take about a month of computing time to break a common form of RSA encryption. Achieving the same in a day would require 471,000 qubits.

Several quantum computing companies are trying to build quantum computers with hundreds of thousands of qubits within a decade, and the new estimate is largely agnostic of what they would be made of, relying only on their error rates and the speed of quantum computers. Leaving aside the practicality of running the calculation for a month, could the Iceberg Quantum scheme actually be implemented in practice? Anyone in charge of a quantum computer that could do this would have access to many emails, bank accounts, or even confidential government files protected by RSA encryption.

“These more stringent requirements make it harder to make hardware, and making hardware is already the hardest part,” says Gidney. Similarly, Scott Aaronson at the University of Texas at Austin he wrote it on his blog his main reservation about the new estimate is the difficulty of practically engineering the necessary connections between distant qubits.

IBM researchers have been pushing qLDPC codes in recent years to make the company’s quantum computing hardware more accessible, but how successful the approach might be remains unclear. An IBM spokesman said in a statement that qLDPC codes would be the “cornerstone” of its quantum computers, but did not comment on whether the new scheme could be implemented.

Connections between distant qubits are much easier to implement when they are made of extremely cold atoms or ions, two quantum computing approaches that have gained ground in recent years. But these quantum computers also operate more slowly, which a new study suggests could put them back into the millions when it comes to cracking RSA encryption.

“I think it’s important to never be conservative about the timelines of when things like this happen,” says Lawrence Cohen, also of Iceberg Quantum. “There would be big consequences for someone breaking RSA, and it’s always much, much better to be wrong because it could happen sooner rather than later.”

He says that breaking RSA encryption is a well-studied problem and therefore a great benchmark for anyone looking to build a powerful quantum computer, but his team’s approach could also be used to run better and more useful simulations of quantum materials and quantum chemistry.

topics:

• security/
• quantum computing