  In this paper, a secure quantum dialogue protocol via cavity QED is suggested
by using the evolution law of atom in cavity QED. The present protocol employs
both the two-step transmission and the unitary operation encoding. Two security
checks are adopted to ensure its transmission security against the active
attacks from an outside eavesdropper. The present protocol avoids the
information leakage problem by using the entanglement swapping between any two
Bell states via cavity QED together with the shared secret Bell state. Compared
with the previous information leakage resistant quantum dialogue protocol via
cavity QED, the present protocol takes advantage in quantum measurement.
