Source
We have all heard about how quantum computers will destroy security, since they will be able to "crack" the keys that we all use to protect our access to banks and other entities.
As you all know, the system used is the asymmetric cryptography system, a cryptographic method that uses a pair of keys for transactions, a public one that can be given to anyone and a private one that we keep as gold in cloth. The system guarantees that these keys can only be generated once, which guarantees that no two will be the same.
These keys are made up of prime numbers of up to 256 digits and the public key is the result of multiplying two of these monstrous prime numbers. In order to discover the private key from the public key, it is necessary to find out that two prime numbers have been used, which, today, would be impossible to achieve even combining the processing capacity of all existing computers.
Source
The fact is that quantum computers, by design, would be able to decompose the public key into the two cousins that form it in a matter of seconds, which would jeopardize all computer security.
To prevent this from happening, experts have designed the QKD (Quantum Key Distribution) system that takes advantage of the properties of quantum mechanics to ensure that communications cannot be intercepted.
According to the laws of quantum mechanics, the simple fact of observing reality causes it to change, making it impossible to intercept these keys since they would be altered and the emitter and receiver would realize that it had been "cracked".
Source
In addition to being done by land using fiber optics, since 2016 China has been testing to achieve this type of satellite communication to send information between said satellite and a ground-based telescope, beating several records in the time it has been operating.
In this case, although the distance of 1,200 km had already been exceeded, they have managed to send information between two separate telescopes 1,120 km apart, using the satellite as a link.
So you can sleep peacefully that nobody will break your keys.
Versión en español