  We derive a general framework for a quantum metrology scheme where the
quantum probes are exchanged via an unsecured quantum channel. We construct two
protocols for this task which offer a trade-off between difficulty of
implementation and efficiency. We show that, for both protocols, a malicious
eavesdropper cannot access any information regarding the unknown parameter. We
further derive general inequalities regarding how the uncertainty in a resource
state for quantum metrology can bias the estimate and the precision. From this,
we link the effectiveness of the cryptographic part of the protocol to the
effectiveness of the metrology scheme with a (potentially) malicious probe
resource state.
