  In a recent paper (Scheme of the arrangement for attack on the protocol BB84,
Optik 127(18):7083-7087, Sept 2016), a protocol was proposed for using weak
measurement to attack BB84. This claimed the four basis states typically used
could be perfectly discriminated, and so an interceptor could obtain all
information carried. We show this attack fails when considered using standard
quantum mechanics, as expected - such ``single-shot" quantum state
discrimination is impossible, even using weak measurement.
