Inside the quest for unbreakable encryption
Cryptographers want encryption schemes that are impossible for tomorrow’s quantum computers to crack. There’s only one catch: they might not exist.
When we check email, log in to our bank accounts, or exchange messages on Signal, our passwords and credentials are protected through encryption, a locking scheme that uses secrets to disguise our data. It works like a cyber padlock: with the right key someone can unlock the data. Without it, they’ll have to resort to laborious brute-force methods, the digital equivalent of hacksaws and blowtorches.
Our trust in online security is rooted in mathematics. Encryption schemes are built on families of math problems called one-way functions—calculations that are easy to carry out in one direction but almost impossible to solve efficiently from the other, even with a powerful computer. They’re sort of a computational equivalent of those road spikes found at the exits of airport car rental agencies. Drive in one direction and you barely notice. Hit reverse and you won’t get far (and will need new tires).
There’s a problem, however. Although mathematicians suspect true one-way functions exist, they have yet to prove it. They haven’t proved that the thorny problems we do use are impossible, or even extremely impractical, to solve. Instead, it could just be that we haven’t yet found the appropriate mathematical means to take the problems apart. This conundrum haunts all encryption. Our data is secured by the fact that no one knows how to crack the schemes that protect it—at least not yet.
It’s not just today’s hackers we may need to worry about. Security experts have long warned of a threat that hasn’t yet materialized: quantum computers. In the future these machines could execute a program that quickly solves the math problems behind today’s state-of-the-art encryption. That threat puts personal financial, medical, and other information at risk. Hackers could steal today’s encrypted data and store it away, just waiting for the arrival of new technological lockpicks.