These are anxious times. For the worriers among us 2020 has been a bumper year. We’ve had a global pandemic and the rise of Fascism in democratic countries. Not content with this, the techno-literate fretful have added ‘Quantum Supremacy’ (i.e. the point at which quantum computers outperform their digital traditional cousins) to the list of concerns.
It is easy to forget that an absolutely secure computer system does not exist. Public key cryptography like RSA, elliptic curve, Diffie-Hellman, etc. makes it absurdly difficult, but not impossible to circumvent its well-designed security measures. If it wasn’t for the small issue of the Heat Death of the Universe, a traditional computer could access your client’s private data in a mere few hundred billion years. That is to say vulnerabilities exist, but currently they are practically impossible to exploit.
Inevitably the greatest threat to your encrypted data will always be bad cryptography practices and human error, but quantum computing, unbound by the limitations of traditional digital computation, makes cracking public key encryption entirely possible.
The Doom and Gloom
Depending on the quality of the qubits involved, 2048-bit RSA encryption can be cracked in 8 hours or, if you have a few thousand perfectly stable qubits, a handful of seconds. Symmetric cryptography might withstand a quantum attack but the effective keysize would be halved. The catastrophic consequences are unlimited. Think about how easy it would be to force a code update using a forged signature leading to the takeover of millions of devices. Billions of financial transactions are now insecure.