A note on quantum algorithms and the minimal degree of epsilon-error polynomials for symmetric functions (pp0943-0950)
          Ronald de Wolf
          doi: https://doi.org/10.26421/QIC8.10-4
Abstracts: In this paper, we investigate limitations imposed by sequential attacks on the performance of a differential-phase-shift (DPS) quantum key distribution (QKD) protocol with weak coherent pulses. Specifically, we analyze a sequential attack based on optimal unambiguous discrimination of the relative phases between consecutive signal states emitted by the source. We show that this attack can provide tighter upper bounds for the security of a DPS QKD scheme than those derived from sequential attacks where the eavesdropper aims to identify the state of each signal emitted by the source unambiguously.
Key words: quantum cryptography, quantum key distribution, differential-phaseshift quantum key distribution, unambiguous state discrimination, sequential attack, intercept-resend attack, security