  An author (arXiv:1709.09262 [quant-ph] (2017), Nanoscale Research Letters
(2017) 12:552) has recently questioned the security of two-way quantum key
distribution schemes by referring to attack strategies which leave no errors in
the (raw) key shared by the legitimate parties. We argue that the article is
based on a flawed understanding of the actual workings of a two-way protocol,
thus the erroneous conclusions drawn thereof.
