  Vulnerabilities and imperfections of single-photon detectors have been shown
to compromise security for quantum key distribution (QKD). The
measurement-device-independent QKD (MDI-QKD) appears to be the most appealing
solution to solve the issues. However, in practice one faces severe obstacles
of having significantly lower key generation rate, difficult two photon
interferences, and remote synchronization etc. In this letter, we propose a
highly efficient and simple quantum key distribution scheme to remove all of
these drawbacks. Our proposal can be implemented with only small modifications
over the standard decoy BB84 system. Remarkably it enjoys both the advantages
of high key generation rate (being almost two orders of magnitude higher than
that based on conventional MDI-QKD) comparable to the normal decoy system, and
security against any detector side channel attacks. Most favorably one can
achieve complete Bell state measurements with resort to single photon
interference, which reduces significantly experimental costs. Our approach
enables utilization of high speed and efficient secure communication,
particularly in real-life scenario of both metropolitan and intercity QKD
network, with an attack free fashion from arbitrary detector side channels.
