A bidirectional switching method and apparatus for implementing key

The present invention discloses a method of bidirectional switching device for implementing a key and. Wherein the method comprises: either end of the communications link to set a new transmission direction keys when new key is not available and a new key set reception direction is available; the estimated or determined at either end to end at least n obtained after the new key, the first key is invalid before the start of the original key handover process, the original key transmission direction set as a new key is not available and the transmission direction is made available; wherein, N ≥ n ≥1, N is the total number of receivers corresponding to the sender; either end of the selection keys effective protection deprotection according to the identifier of the peer data transmission; at either end of the first time the later deprotection of the successful new key data key to start the second handover procedure, the original key reception direction is set as unavailable. The present invention is sequentially switched by each key end defining a communications link, either end to ensure that the data can be deprotected sends correct.