Аннотация:Early proofs of key secrecy in quantum cryptography systems were based on the assumption thatthe transmitting and receiving stations are completely isolated from the outside world—the eavesdropper.However, this condition cannot be implemented in practice since quantum cryptography systems are opensystems in the sense that the eavesdropper may have indirect access, for example, through a fiber communicationchannel, to the critical elements of the equipment (phase modulators, intensity modulators, etc.) usingactive probing of the state of these elements. The state of the elements carries information about the transmittedkey. In addition, the eavesdropper can use passive detection of side radiation from the receiving and transmittingequipment. Signals in side channels of information leakage may have extremely low intensity and areactually quantum signals. The eavesdropper may use the joint measurement of quantum information statesin the communication channel and of states in various side channels of information leakage. The paper considersboth passive attacks with measurement of side radiation and active attacks involving the probing of thestates of the phase modulator and the intensity modulator, as well as backscattering radiation of single-photonavalanche detectors, which occurs during detecting information states on the receiver side. Combined attacksare also considered. The decoy state method is generalized with regard to active probing attacks, and boundariesfor state parameters in side communication channels are obtained that guarantee secret key distributionfor a given length of the communication channel.