ITMO: The receiver for transfer of keys of quantum enciphering

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• Cryptography
• Quantum cryptography

2020: The announcement of the receiver for transfer of keys of quantum enciphering

On July 14, 2020 it became known that scientists of ITMO offered modification of a system of quantum enciphering with the compact detector.

The ITMO offered modification of a system of quantum enciphering with the compact detector. Photo: popmech.ru.

As it was reported, development can reduce the price of creation of mass networks of the quantum distribution of a key (QDK) that will take their available to more wide range of users. Work of scientists will allow to use infrastructure of normal fiber optic communication lines for KRK. Work of scientists is published in the Scientific Reports magazine.

Quantum distribution of encryption keys – it still sometimes is called quantum enciphering - it is one of data coding methods. As the carrier of information in the KRK system the quantum radiation which signal it is very difficult to intercept to malefactors is used.

In quantum distribution of keys the weakened laser light with a median number of photons is, as a rule, used it is less than unit. Such light has fundamental features – so-called quantum effects which do not give the chance to the third party to put in the canal and to consider information, having remained at the same time unnoticed. Eduard Samsonov, the research associate of faculty of photonics and optoinformation science of the ITMO University told

Demand for the systems of quantum distribution of encryption keys grows constantly. However the problem gets in the way of its mass implementation: such data transmission systems require very difficult and expensive equipment. Besides, for creation of such systems hardly it is possible to use already existing infrastructure of fiber optic communication. Recently the staff of the ITMO University published work in which offered a solution of this problem.

Scientists of the ITMO University developed the KRK system with the compact coherent detector on the basis of the protocol of quantum distribution of a key at side frequencies on which researchers from St. Petersburg work already long enough.

The main feature of the protocol is the method of formation of statuses using the electrooptical phase modulator.

So if at you radiation goes at a certain optical frequency, then as a result of phase shift keying side frequencies which bear information on a phase of the transmitted signal form. If the index of modulation weak, then and luminous radiation at such side frequencies is weak. Eduard Samsonov, the research associate of faculty of photonics and optoinformation science of the ITMO University explained

Scientists consider the main achievement for July, 2020 development of a method of coherent acceptance for such system. Use of the bearing optical frequency which in itself does not bear information, but which can be used as a phase of a poor signal, reference for registration, from side frequencies is its cornerstone.

Actually scientists suggest to deliver one more modulator similar to what was created by an initial signal at side frequencies, but with the increased index of modulation, and again to carry out through it a signal. Thus additional side frequencies which interact with those that came from the transmitter are recreated. At a constructive interference the most part of radiation will appear at side frequencies and, on the contrary, at destructive the most part radiation will appear at a center frequency that can be registered by the balance detector.

At the same time in such system reliability and security of quantum distribution of encryption keys remains. Researchers constructed a mathematical model of the offered scheme which will well be approved with experimental data, and offered the analysis of stability of the drafted protocol to the collective attacks.