While browsing the web, you might not realize that the security of your online transactions is guaranteed by a hard-to-crack math problem called factoring. But this security could evaporate in an instant—if a big enough quantum computer is built. Computers that store information in quantum hardware—like individual ions, atoms or photons—would make quick work of the factoring problem and threaten the safety of current protocols. To thwart the threat posed by possible quantum computers, the National Institute of Standards and Technology (NIST) has been running a kind of competition.