Professor Masato Koashi of the University of Tokyo proposed a quantum cryptography method based on a completely different principle.This is the first time in 30 years that a new method of quantum cryptography has been proposed, and it has paved the way for the conversion from the conventional "noticeable when read" cryptography to the "unreadable" method.
Until now, quantum cryptography has detected eavesdropping based on the uncertainty principle.The uncertainty principle is that observing minute particles and light will affect the state of the object, no matter how good the measuring device is.By doing this, if information is stolen in the middle of communication, it is possible to find out how much information was seen.However, it takes time and effort such as having to monitor the communication path.Another drawback is that encryption is difficult with a small amount of information.
In the new principle proposed this time, the sender first puts the information on the light and sends it.The receiving side divides this light into two with a magic mirror etc. so that one arrives with a delay.Then, the two signals that arrive at different timings are overlapped and received.This alone proved that security can be ensured without monitoring the communication channel.Due to the quantum mechanical properties of light, it is extremely unlikely that data will be exposed to meaningful information by snooping on it, and high security can be ensured against all eavesdropping methods.It is also said that it can be applied to communication with a small amount of information.
The new method can be realized using existing communication equipment without using special equipment.Furthermore, by switching from "notice when read" to "not read in the first place", security can be improved and the trouble of monitoring communication channels can be eliminated.By discovering a method that no one has noticed for 30 years since the first quantum cryptography was invented, it may be possible to apply it in a wide range not limited to communication.
Source:[The University of Tokyo] "New Principles for Quantum Cryptography for the First Time in XNUMX Years" -From "Notice When Read" to "Unreadable" Method- (PDF)