Аннотация:The security of cryptographic keys in quantum cryptography systems is guaranteed by fundamental quantum
mechanical exclusion principles. A quantum channel through which quantum states are transferred is not
controlled and an eavesdropper can perform any modifications with it. The security of quantum key distribu
tion protocols has already been proved [M. Tomamichel et al., Nature Commun. 3, 634 (2011); S. N. Molot
kov, J. Exp. Theor. Phys. 115, 969 (2012)], including the realistic case of a finite length of transmitted
sequences. It is always assumed that the eavesdropper has neither direct nor indirect access to the transmitting
and receiving equipment. The real situation is somewhat different. The preparation and detection of quantum
states occur according to random sequences that are generated on the transmitter and receiver sides. Detect
ing electromagnetic radiation generated in these processes, the eavesdropper can obtain additional informa
tion on a key. The upper quantummechanical bound on the amount of information of the eavesdropper on
the key that can be obtained through a side channel has been determined.