Counterfactual attack on counterfactual quantum key distribution
School of Electronic Science and Engineering, National University of Defense Technology - Changsha 410073, China
Accepted: 17 April 2012
It is interesting that counterfactual quantum cryptography protocols allow two remotely separated parties to share a secret key without transmitting any signal particles. Generally, these protocols, expected to provide security advantages, base their security on a translated no-cloning theorem. Therefore, they potentially exhibit unconditional security in theory. In this letter, we propose a new Trojan horse attack, by which an eavesdropper Eve can gain full information about the key without being noticed, to real implementations of a counterfactual quantum cryptography system. Most importantly, the presented attack is available even if the system has negligible imperfections. Therefore, it shows that the present realization of counterfactual quantum key distribution is vulnerable.
PACS: 03.67.Dd – Quantum cryptography and communication security / 03.67.Hk – Quantum communication / 42.50.Ex – Optical implementations of quantum information processing and transfer
© EPLA, 2012