Semtech LoRa Edge LR1110, User Manual

Page: 109 / 130

LR1110
User Manual
Rev.1.0
UM.LR1110.W.APP March 2020
109 of 130
Semtech
www.semtech.com
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DecKeyID and VerKeyID are defined in Table 12-1: Cryptographic Keys Usage and Derivation :
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DecKeyID specifies the key used for decryption of the message.
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VerKeyID specifies the key used for the MIC verification.
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Depending on the LoRaWanVer , the expected Header size N is 1 byte (v1.0) or 12 bytes (v1.1).
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LoRaWanVer =0: LoRaWAN verison 1.0
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LoRaWanVer =1: LoRaWAN verison 1.1
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...
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Header1, ... ,HeaderN : Header
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Data1, ... ,DataN : Data. Data size M is either 16 Bytes or 32 Bytes. Data must include the encrypted MIC.
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CEStatus is defined in section CEStatus on page 107 .
12.3.5
CryptoComputeAesCmac
The command CryptoComputeAesCmac ( ) will compute the AES CMAC of the provided data using the specified Key and
return the MIC.
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KeyID : specified Key ID, as defined in Table 12-1: Cryptographic Keys Usage and Derivation . Goes from 0 to 27.
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Data1, Data2, ... , DataN : Provided data, considered as Byte buffers.
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CEStatus : defined in section CEStatus on page 107 .
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MIC : Message Integrity Check (first 4 bytes of the CMAC).
Table 12-7: CryptoProcessJoinAccept Response
Byte 0 1 2 ... M+3
Data from Host 0x00 0x00 0x00 ... 0x00
Data to Host Stat1 CEStatus Data1 ... DataM
Table 12-8: CryptoComputeAesCmac Command
Byte 0 1 2 3 4 5 … N+3
Data from Host 0x05 0x05
KeyID
(7:0)
Data1 Data2 Data3 … DataN
Data to Host Stat1 Stat2
IrqStatus
(31:24)
IrqStatus
(23:16)
IrqStatus
(15:8)
IrqStatus
(7:0)
… 0x00
Table 12-9: CryptoComputeAesCmac Response
Byte 0 1 2 3 4 5
Data from Host 0x00 0x00 0x00 0x00 0x00 0x00
Data to Host Stat1 CEStatus MIC1 MIC2 MIC3 MIC4