Link key
Link keys are used at the APS layer to provide an extra level of encryption for end-to-end security. The XBee 3 Zigbee RF Module application uses global link keys for both joining and APS-encrypted transmissions. When joining a network with encryption enabled, the network key is securely exchanged by encrypting it with the link key.
When using a centralized trust center, the link key that is used to join is exchanged with a more secure key that is randomly generated by the trust center.
This section provides information about the types of link keys.