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Breaking encryption with a quantum computer just got 20 times easier

A quantum computer with a million qubits would be able to crack the vital RSA encryption algorithm, and while such machines don't yet exist, that estimate could still fall further

By Matthew Sparkes

23 May 2025

Quantum computers have long been a potential threat to encryption

sakkmesterke/Shutterstock

Quantum computers could crack a common data encryption technique once they have a million qubits, or quantum bits. While this is still well beyond the capabilities of existing quantum computers, this new estimate is 20 times lower than previously thought, suggesting the day encryption is cracked is closer than we think.

The widely used RSA algorithm relies on the fact that multiplying two prime numbers to generate a large encryption key is easy, but finding those original prime factors when all you have is the resulting key is…

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