On the side quantum–classical binary channel of information leakage with Gaussian noise

The detection of side radiation of transmitting devices is an additional source of information on distributed keys. In contrast to the attack on a quantum communication channel, the detection of side radiation does not lead to perturbation of information states and errors on the receiving side. To ensure the cryptographic security of quantum cryptography systems on the receiving side, it is fundamentally necessary to estimate the amount of information leakage through the side channel. A simple quantum derivation of amount of information leakage through the side quantum channel with Gaussian noise has been reported. The proposed method is applicable not only to the channel with Gaussian noise but also to other types of side channels of information leakage.