We investigate a new strategy for incoherent eavesdropping in Ekert's entanglement based quantum key distribution protocol. We show that under certain assumptions of symmetry the effectiveness of this strategy reduces to that of the original single qubit protocol of Bennett and Brassard.
@article{arxiv.quant-ph/0103058,
title = {Security of EPR-based Quantum Cryptography against Incoherent Symmetric Attacks},
author = {Hitoshi Inamori and Luke Rallan and Vlatko Vedral},
journal= {arXiv preprint arXiv:quant-ph/0103058},
year = {2009}
}