  Optical physical unclonable keys are currently considered to be rather
promising candidates for the development of entity authentication protocols,
which offer security against both classical and quantum adversaries. In this
work we investigate the robustness of a continuous-variable protocol, which
relies on the scattering of coherent states of light from the key, against
three different types of intercept-resend emulation attacks. The performance of
the protocol is analysed for a broad range of physical parameters, and our
results are compared to existing security bounds.
