  A quantum key distribution and identification protocol is proposed, which is
based on entanglement swapping. Through choosing particles by twos from the
sequence and performing Bell measurements, two communicators can detect
eavesdropping, identify each other and obtain the secure key according to the
measurement results. Because the two particles measured together are selected
out randomly, we need neither alternative measurements nor rotation of the Bell
states. Furthermore, less Bell measurements are needed in our protocol than in
the previous similar ones.
