4.4 Message Integrity Code (MIC)
- The message integrity code (MIC) is calculated over all the fields in the message.
- msg =MHDR|FHDR|FPort|FRMPayload
- whereby len(msg) denotes the length of the message in octets.
- The MIC is calculated as follows [RFC4493]:
29
- cmac = aes128cmac(NwkSKey, _B0 | msg)
- MIC =cmac[0..3]
| 32 | ||||||||
|---|---|---|---|---|---|---|---|---|
| 33 | whereby the block B0 is defined as follows: | |||||||
| Size (bytes) | 1 | 4 | 1 | 4 | 4 | 1 | 1 | |
| B0 | 0x49 | 4 x 0x00 | Dir | DevAddr | FCntUp or | 0x00 | len(msg) | |
| FCntDown | ||||||||
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The authors reserve the right to change specifications without notice.
LoRaWAN Specification
1
2 The direction field (Dir) is 0 for uplink frames and 1 for downlink frames.
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The authors reserve the right to change specifications without notice.
LoRaWAN Specification