The original version of This story appeared in How many magazine.

Difficult problems are generally not a welcome show. But cryptographers love them. This is because some difficult mathematics problems underlie the safety of modern encryption. Any intelligent tip to solve them will condemn most forms of cryptography.

Several years ago, researchers found A radically new approach to encryption This is missing this potential weak point. The approach exploits the particular characteristics of quantum physics. But unlike the previous quantum encryption schemes, which only work for a few special tasks, the new approach can perform a much wider range of tasks. And it is to work on the whole problem at the heart of ordinary “classic” “classic” cryptography is easily resolved.

But this striking discovery noted unrealistic hypotheses. The result was “more proof of concept,” said Firm butCrypto researcher at Simons Institute for Theory of Computing in Berkeley, California. “This is not a statement on the real world.”

Now, a New paper By two cryptographers followed a path to quantum cryptography without these supposed bizarre. “This article is sad that if some other conjectures are true, then quantum cryptography must exist”, but said.

Castle in the sky

You can consider modern cryptography as a tower with three essential parts. The first part is the foundation deeply under the tower, which is made of hard mathematical problems. The tower itself is the second part – you can find specific cryptographic protocols that allow you to send private messages, sign digital documents, secrets of secret voting, etc.

Between the two, securing these daily applications in the mathematical base, is a base in construction blocks called Unidirectional functions. They are responsible for the asymmetry inherent in any encryption scheme. “It is one -way because you can encrypt messages, but you cannot decipher them,” said Mark ZhandryA cryptographer at NTT Research.

In the 1980s, researchers proved that cryptography built at the top of unidirectional functions would ensure the safety of many different tasks. But decades later, they are still not sure that the foundation is strong to support it. The problem is that the rocky substratum is made of particular difficult problems – of the technical problem under the name of problem NP – whose definition of functionality is that it is easy to check where a candidate solution is correct. (For example, dividing a number into its primary factors is an NP problem: difficult to do for a large number, but easy to check.)

Many of these problems seem intrinsically difficult, but computer scientists I couldn’t test it. If someone sproms an ingenious algorithm to quickly solve the hardest NP problems, the foundation will collapse and the whole tower will collapse.

Unfortunately, you can’t just move your turn elsewhere. The Tower Foundation – works on a route – can only be seated on a basis of NP problems.

To build a tower on more difficult problems, cryptographers would need a new foundation which is not made of unidirectional functions. It seemed impossible until a few years ago, when researchers realized that quantum physics could help.