In this Comment we question the security of the recently proposed scheme of a quantum dense key distribution by Degiovanni et al. [Phys. Rev. A69, 032310 (2004)].
Eavesdropping schemes: (a) error tuning mode, (b) eavesdropping mode (attack on Alice key), and (c) eavesdropping mode (attack on Bob key).Reuse & Permissions