Semtech LR1121 - Cryptoderivekey; Table 10-4: Cryptoderivekey Command; Table 10-5: Cryptoderivekey Response

LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
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10.3.3 CryptoDeriveKey
Command CryptoDeriveKey(...) derives (encrypts) into a specific Key identified by DstKeyID, the input (including the
LoRaWAN DevNonce) value provided, using a source key identified by SrcKeyID.
• DstKeyID and SrcKeyID for this function are defined in Table 10-1: Cryptographic Keys Usage and Derivation.
 DstKeyID: Destination Key ID. Valid values are from 4 to 25.
 SrcKeyID: Source Key IDs 2-3 and 6-11 are possible for this function.
• Input[1:16] is an array of bytes. An example of its construction is given in Section 11.3 and Section 11.4.
• CEStatus is defined in section CEStatus on page 103.
Note: At the end of the CryptoDeriveKey() process, the generated key is located in the dedicated Crypto Engine RAM, and
can be stored in the flash memory using the CryptoStoreToFlash() command.
Table 10-4: CryptoDeriveKey Command
Byte 0 1 2 3 4 5 6 … 19
Data from Host 0x05 0x03
SrcKeyID
(7:0)
DstKeyID
(7:0)
Input[1:16]
Data to Host Stat1 Stat2
IrqStatus
(31:24)
IrqStatus
(23:16)
IrqStatus
(15:8)
IrqStatus
(7:0)
0x00 … 0x00
Table 10-5: CryptoDeriveKey Response
Byte 0 1
Data from Host 0x00 0x00
Data to Host Stat1 CEStatus