Ensuring authenticity in Xbee Series 1

I have been working with Xbee for few days and intending to use Xbee (Series 1) +Arduino UNO as part of Wireless Sensor Network. I want the network to be secured, I can use the Xbee’s AES capability to make the data transfer secure. But I want to make sure that the sender/receiver all are authentic. How can I be able to ensure that? I want to use AT mode.

What I am trying to say is, suppose there are few nodes (Xbee+Arduino) which collects data by sensor and there is one receiver. The receiver sends command to one of the sensor node (one to one communication) to collect sensor value from that node. My question is, how can that sensor node will be able to know that, the commander is authentic, not some adversary [that somehow knows the command format and sending the command pretending itself as commander]? Is there anyway to configure the Xbee so that it can respond to only authentic commander? There will be only one commander in the network, but is there anyway to set sensor xbee [as we can configure destination address] so that it will only respond to the authentic commander?

All traffic and commands will be transacted using the encryption key (EE.) Nodes without this key will be unable to send on the network. If you were to use API mode you could also discover the address of the sending node and act accordingly. What other security are you looking for?

No that product does not offer an Auth. function using the ASE encryption. But if they do not have the correct KY value, you will only get gibberish for output from that unwanted node.