Breaking RSA With a Quantum Computer
upstart writes:
Quantum computers can break major encryption method, researchers claim:
Breaking RSA With a Quantum Computer - Schneier on SecurityA group of researchers has claimed that quantum computers can now crack the encryption we use to protect emails, bank accounts and other sensitive data. Although this has long been a theoretical possibility, existing quantum computers weren't yet thought to be powerful enough to threaten encryption.
upstart writes:
Breaking RSA with a Quantum Computer - Schneier on Security:
A group of Chinese researchers have just published a paper claiming that they can-although they have not yet done so-break 2048-bit RSA. This is something to take seriously. It might not be correct, but it's not obviously wrong.
We have long known from Shor's algorithm that factoring with a quantum computer is easy. But it takes a big quantum computer, on the orders of millions of qbits, to factor anything resembling the key sizes we use today. What the researchers have done is combine classical lattice reduction factoring techniques with a quantum approximate optimization algorithm. This means that they only need a quantum computer with 372 qbits, which is well within what's possible today. (The IBM Osprey is a 433-qbit quantum computer, for example. Others are on their way as well.)
The Chinese group didn't have that large a quantum computer to work with. They were able to factor 48-bit numbers using a 10-qbit quantum computer. And while there are always potential problems when scaling something like this up by a factor of 50, there are no obvious barriers.
Honestly, most of the paper is over my head-both the lattice-reduction math and the quantum physics. And there's the nagging question of why the Chinese government didn't classify this research. But...wow...maybe...and yikes! Or not.
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