User Manual

Operation Encryption

XBee/XBee-PRO S2C 802.15.4 RF Module User Guide

Broadcast PAN ID

The Broadcast PAN ID is also 0xFFFF. Its effect is to traverse all PANs in the vicinity. Typically, this only

makes sense during association time when sending beacon requests to find PAN IDs.

Short and long addresses

A short address is 16 bits and a long address is 64 bits. The short address is set with the MY

parameter. If the short address is 0xFFFE or 0xFFFF, then the address of the device is long and it is

the serial number of the device as read by the SH and SL parameters.

Note When an end device associates to a coordinator, it is assigned the short address of 0xFFFE.

Encryption

The XBee/XBee-PRO S2C 802.15.4 RF Module supports AES 128-bit encryption. 128-bit encryption

refers to the length of the encryption key entered with the KY command. (128 bits = 16 bytes.) The

802.15.4 protocol specifies eight security modes, enumerated as shown in the following table.

Level Name Encrypted?

Length of Message Integrity

Check

Packet Length

overhead

0 N/A No 0 (no check) 0

1 MIC-32 No 4 9

2 MIC-64 No 8 13

3 MIC-128 No 16 21

4 ENC Yes 0 (no check) 5

5 ENC-MIC-32 Yes 4 9

6 ENC-MIC-64 Yes 8 13

7 ENC-MIC-

128

Yes 16 21

The XBee/XBee-PRO S2C 802.15.4 RF Module only supports security levels 0 and 4. It does not support

message integrity checks. EE 0 selects security level 0 and EE 1 selects security level 4. When using

encryption, all devices in the network must use the same 16-byte encryption key for valid data to get

through. Mismatched keys will corrupt the data output on the receiving device. Mismatched EE

parameters will prevent the receiving device from outputting received data.

Working from a maximum packet size of 116 bytes, encryption affects the maximum payload as shown

in the following table.

Factor

Effect on

Maximum

Payload Comment

Compatibility

mode

Force to 95 If C8 bit 0 is set, all packets are limited to 95 bytes, regardless of other

factors listed below. This is how the Legacy 802.15.4 module (S1

hardware) functions.