The US Department of Commerce’s National Institute of Standards and Technology (NIST) has selected four cryptography algorithms — CRYSTALS-Kyber, CRYSTALS-Dilithium, FALCON, and SPHINCS+ — that will become part of the NIST’s post-quantum cryptographic standard, which is expected to be finalised in the next two years.
These algorithms are the first set of encryption tools that’ll be able to withstand decryption attacks on future quantum computers and will be replacing any algorithms that can’t. The four encryption algorithms are also the first winners in NIST’s six-year-old competition.
The competition was initiated in 2016 by the organisation as a challenge to the best cryptographers around the world to build and vet encryption algorithms strong enough to withstand attacks from a future quantum computer. It would be comparatively stronger than present-day encryption algorithms.
CRYSTALS-Kyber will be used for general encryption as it generates digital keys that two computers that have never interacted with each other can use to decrypt data. The other three, CRYSTALS-Dilithium, FALCON, and SPHINCS+, will be used for digital signatures.
Of these four, CRYSTALS-Kyber and CRYSTALS-Dilithium are the two most likely replacements selected for their robust security and good performance.
FALCON will also be standardised as the NIST fears that in some cases, the key size for CRYSTALS-Dilithium signatures might be too large. Finally, SPHINCS+ is selected to avoid dependence on lattice security for signatures. The NIST has also asked for public feedback on a version of SPHINCS+ with a lower number of maximum signatures.
These algorithms’ selection also marks the finalisation of NIST’s post-quantum standardisation project. These four algorithms are expected to have significant influence as we advance.
No one knows when exactly Quantum computers will be available. However, with significant advancements and ongoing follow-up research, many researchers fear that state-backed threat actors and even regular criminals might intercept and store encrypted data when the technology becomes available.