“The first thing organizations need to do is understand where they are using crypto, how, and why,” says El Kaafarani. “Start assessing which parts of your system need to switch, and build a transition to post-quantum cryptography from the most vulnerable pieces.”
There is still a great degree of uncertainty around quantum computers. No one knows what they’ll be capable of or if it’ll even be possible to build them at scale. Quantum computers being built by the likes of Google and IBM are starting to outperform classical devices at specially designed tasks, but scaling them up is a difficult technological challenge and it will be many years before a quantum computer exists that can run Shor’s algorithm in any meaningful way. “The biggest problem is that we have to make an educated guess about the future capabilities of both classical and quantum computers,” Young says. “There’s no guarantee of security here.”
The complexity of these new algorithms makes it difficult to assess how well they’ll actually work in practice. “Assessing security is usually a cat-and-mouse game,” says Artur Ekert, a quantum physics professor at the University of Oxford and one of the pioneers of quantum computing. “Lattice based cryptography is very elegant from a mathematical perspective, but assessing its security is really hard.”
The researchers who developed these NIST-backed algorithms say they can effectively simulate how long it will take a quantum computer to solve a problem. “You don’t need a quantum computer to write a quantum program and know what its running time will be,” argues Vadim Lyubashevsky, an IBM researcher who contributed to the CRYSTALS-Dilithium algorithm. But no one knows what new quantum algorithms might be cooked up by researchers in the future.
Indeed, one of the shortlisted NIST finalists—a structured lattice algorithm called Rainbow—was knocked out of the running when IBM researcher Ward Beullens published a paper entitled”Breaking Rainbow Takes a Weekend on a Laptop.” NIST’s announcement will focus the attention of code breakers on structured lattices, which could destroy the whole project, Young argues.
There is also, Ekert says, a careful balance between security and efficiency: In basic terms, if you make your encryption key longer, it will be more difficult to break, but it will also require more computing power. If post-quantum cryptography is rolled out as widely as RSA, that could mean a significant environmental impact.
Young accuses NIST of slightly “naive” thinking, while Ekert believes “a more detailed security analysis is needed”. There are only a handful of people in the world with the combined quantum and cryptography expertise required to conduct that analysis.
Over the next two years, NIST will publish draft standards, invite comments, and finalize the new forms of quantum-proof encryption, which it hopes will be adopted across the world. After that, based on previous implementations, Moody thinks it could be 10 to 15 years before companies implement them widely, but their data may be vulnerable now. “We have to start now,” says El Kaafarani. “That’s the only option we have if we want to protect our medical records, our intellectual property, or our personal information.”