  We show that a quantum network can protect the identity of a sender and
receiver from an external wiretapper. This new quantum communication protocol,
which we call secure quantum routing, requires only single photons routed by
linear optical elements and photon counters, and does not require distributing
entanglement over multiple nodes or active feedforward. We prove that secure
quantum routing protects both the contents of the message and the identity of
the sender and receiver, and creates only a negligible reduction in the network
channel capacity.
