). One of the steps in Shor’s quantum algorithm can efficiently break an elliptic-curve key, too.
A popular approach to lattice-based cryptography is called learning with errors , which forms the basis for several of the NIST finalists. It was introduced in 2005 by computer scientist Oded Regev at New York University. In its simplest form, it relies on arithmetic. To create a public key, the person who wants to receive a message picks a large, secret number — the private key.
Under Moody’s lead, NIST had already been working on the contest that it announced in 2016, in which it invited computer scientists to submit candidate post-quantum algorithms for public-key cryptography, releasing them for scrutiny by the research community. At the same time, NIST called for submissions of digital-signature algorithms — techniques that enable a web server to establish its identity, for example, to prevent scammers from stealing passwords.
Still, because cryptography affects sensitive national interests, other countries are keeping a close eye — and some are cautious. “The maturity of post-quantum algorithms should not be overestimated: many aspects are still at a research state,” says cryptography specialist Mélissa Rossi at the National Cybersecurity Agency of France in Paris. Nevertheless, she adds, this should not delay the adoption of post-quantum systems to strengthen current cryptography.
Selecting and standardizing algorithms will not be the end of the story. “It’s certainly a solid step to bless a candidate, but as a follow-up, the Internet has to agree on how to integrate an algorithm into existing protocols,” says Nick Sullivan, an applied cryptographer at Internet-services company Cloudflare, who is based in New York City.Credit: Chao-Yang Lu