Large pulse attack as a method of conventional optical eavesdropping in quantum cryptographya paper written in Quantum Cryptography Project at the Department of Electronics and Telecommunications
With large pulse attack, settings of transmitting and/or receiving apparatus are interrogated by external high-power light pulses. Applicability conditions of this method are given. Type and amount of information learned by the eavesdropper is estimated, depending on parameters of the interrogating pulse and apparatus. An experimental set-up for an eavesdropping experiment is proposed and results of successful preliminary measurements are presented. It is concluded that additional protection is necessary for currently implemented quantum key distribution systems. The paper suggests several security measures against this kind of attack.