Hi @brocaar
Thanks for your help, I tried your simulator and it works as a charm.
Just for fun I tried to do my own simulator in python but i didn’t succeed to encrypt the FRMPayload.
Based on the official LoRa alliance specs and a python module for AES i tried to use AES-CTR as explained but I don’t understand very well.
https://pycryptodome.readthedocs.io/en/latest/src/cipher/classic.html#ecb-mode
In fact, the pycryptodome documentation does not specify if it use a block size of ceil(len(pld) / 16) as it’s recommended in the LoRa spec. Moreover they don’t use any counter block in the example (which is quite annoying for a cryptographic technic based on counter blocks)…
As it’s not linked to the Chirpstack solution I would understand that you don’t answer to my question but it would be very helpfull if you do it.
Thanks in advance.