  Secure communication is considered with unreliable entanglement assistance,
where the adversary may intercept the legitimate receiver's entanglement
resource before communication takes place. The communication setting of
unreliable assistance, without security aspects, was originally motivated by
the extreme photon loss in practical communication systems. The operational
principle is to adapt the transmission rate to the availability of entanglement
assistance, without resorting to feedback and repetition. Here, we require
secrecy as well. An achievable secrecy rate region is derived for general
quantum wiretap channels, and a multi-letter secrecy capacity formula for the
special class of degraded channels.
