Osnabrück 2002 – scientific programme

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Q: Quantenoptik

Q 123: Quantum Communication

Q 123.3: Talk

Monday, March 4, 2002, 17:00–17:15, HS 11/215

Intercept-resend attacks on quantum key distribution with weak coherent states — •Marcos Curty and Norbert Lütkenhaus — Quantum Information Theory Group, ZEMO, University Erlangen-Nürnberg

Quantum key distribution (QKD) is a technique which allows two parties to establish a secure secret key. In an ideal quantum optical implementation, the sender use single photons to encode the information he transmits. However, current experiments are not based on single photon sources, but they are usually based on weak coherent pulses (WCP) with a low average photon number. Powerful, but currently unfeasible, eavesdropping attacks, such as the photon number splitting attack (PNS), have been proposed. In this paper we present more simple attacks, based on intercept-resend strategies, but which are available with todays technologies. We investigate to what extend this kind of attacks can render QKD impossible on actual implementations. We provide explicit limits, imposed by these feasible eavesdropping strategies, on the maximal distance achievable.

[1] G. Brassard, N. Lütkenhaus, T. Mor and B.C. Sanders, Phys. Rev. Lett. 85, 1330 (2000).

[2] M. Dusek, M. Jahma and N. Lütkenhaus, Phys. Rev. A 62, 052304 (2000).