A communication method includes receiving, by a terminal device comprising a processor, indication information from a master node. The indication information is used to indicate that a key used for signaling transmission performed between the terminal device and a first secondary node by using a second signaling radio bearer (SRB) is a first key. The first key is used for signaling transmission performed between the terminal device and the master node by using a first SRB. The first secondary node and the master node share one central unit. The communication method also includes determining, by the terminal device, based on the indication information, that the first key is used for signaling transmission performed between the terminal device and the first secondary node by using the second SRB.