Issue link: https://read.uberflip.com/i/1428350
LoRaWAN Remote Multicast Setup v1.0.0 Specification ©2018 LoRa Alliance™ Page 10 of 18 The authors reserve the right to change specifications without notice. o McRootKey = aes128_encrypt(GenAppKey, 0x00 | pad 16 ) 266 o McKEKey = aes128_encrypt(McRootKey, 0x00 | pad 16 ) 267 268 • Derived from the AppKey. LoRaWAN 1.1+ end-devices SHALL use this scheme. 269 o McRootKey = aes128_encrypt(AppKey, 0x20 | pad 16 ) 270 o McKEKey = aes128_encrypt(McRootKey, 0x00 | pad 16 ) 271 272 The McAppSKey and the McNetSKey are then derived from the group's McKey as follow: 273 274 McAppSKey = aes128_encrypt(McKey, 0x01 | McAddr | pad 16 ) 275 McNetSKey = aes128_encrypt(McKey, 0x02 | McAddr | pad 16 ) 276 277 The multicast key derivation scheme is summarized in the following diagram. 278 AESencrypt McAppSKey (index) 0x01 MulticastAddr McNwkSkey (index) 0x02 McKey_encrypted (index) McKEKey McKey (index) SE interface 279 280 Note: using a Key Encryption Key to transport the multicast group 281 McKey allows for a completely secure multicast scheme when using a 282 hardware secure element, when the secure element does not export 283 the McKey, McAppSKey, and McNwkSKey to the outside. It does not 284 increase the security if a full software implementation is used in the 285 end-device. However, for compatibility reason it is recommended to 286 systematically use this scheme. 287 288 The minMcFCount field is the next frame counter value of the multicast downlink to be sent 289 by the server for this group. This information is required in case an end-device is added to a 290 group that already exists. The end-device MUST reject any downlink multicast frame using 291 this group multicast address if the frame counter is < minMcFCount. 292 293 McAddr is the multicast group network address. McAddr is negotiated off-band by the 294 application server with the network server. 295 296 maxMcFCount specifies the life time of this multicast group expressed as a maximum 297 number of frames. The end-device will only accept a multicast downlink frame if the 32bits 298 frame counter value minMcFCount ≤ McFCount < maxMcFCount. 299 300 301