Example Sequence To Perform At Command Xbee Api Frames Over Ble - Digi XBee 3 ZigBee User Manual

Frame descriptions
Phase 3 (Client presents M1)
Frame data field
M1
Phase 4 (Server presents M2)
Frame data field
M2
TX nonce
RX nonce
Upon completion of M2 verification, the session key has been determined to be correct and the API
service is unlocked and allows additional API frames to be used. Content from this point is encrypted
using AES-256-CTR with the following parameters:
Key: The entire 32-byte session key.
n
Counter: 128 bits total, prefixed with the appropriate nonce shared during authentication. The
n
initial remaining counter value is 1.
The counter for data sent into the XBee API Service is prefixed with the TX nonce value (see the
Phase 4 table) and the counter for data sent by the XBee 3 Zigbee RF Module to the client is
prefixed with the RX nonce value.
Example sequence to perform AT Command XBee API frames over
BLE
1. Discover the XBee 3 Zigbee RF Module through scanning for advertisements.
2. Create a connection to the GATT Server.
3. Optional, but recommended: request a larger MTU for the GATT connection.
4. Turn on indications for the API Response characteristic.
5. Perform unlock procedure using unlock frames. See
Digi XBee® 3 Zigbee® RF Module
Offset in frame
5
Offset in frame
5
37
49
BLE Unlock API frame -
BLE Unlock API frame - 0x2C
Length
Hash algorithm digest length
(32 bytes for SHA256)
Length
Hash algorithm digest length
(32 bytes for SHA256)
12-byte (96-bit) random nonce,
used as the constant prefix of
the counter block for
encryption/decryption of data
transmitted to the API service
by the client
12-byte (96-bit) random nonce,
used as the constant prefix of
the counter block for
encryption/decryption of data
received by the client from the
API service
0x2C.
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