QubitLogic
08

Will quantum computers break encryption?

Eventually, some of it. Not today, and the timeline is genuinely disputed.

Shor's algorithm, published in 1994, factors large numbers efficiently on a quantum computer. RSA encryption is built on factoring being hard. So yes, in principle.

In practice, breaking RSA-2048 needs a machine with millions of physical qubits running error-corrected for hours. Today's machines have thousands of physical qubits and hold their state for a fraction of a second. The gap is many orders of magnitude, and estimates of when it closes range from a decade to never.

Two things are worth knowing anyway.

First, "harvest now, decrypt later." An adversary can record encrypted traffic today and decrypt it whenever the hardware arrives. For data that must stay secret for decades, the threat is already present tense.

Second, the replacement already exists. NIST has standardised post-quantum algorithms built on maths that quantum computers are not known to break, and migration is underway across the industry.

Symmetric encryption like AES is far less affected. Quantum attacks weaken it, but doubling the key length restores the margin.