Hi all,

I'm working with the API for The Things Network and I have a number of fields that expect HEX as their input. These are then matched to the equivalent values sent by the LoRaWAN devices for "shared key" authentication.

As an example, there is a field called "net_key" which is a 16 byte string, and at the moment I'm just generating a string via secrets.hex(16), however on the end devices I need to convert that into an array with each of the couplets split out, which then needs to be converted into a byte array

For example, if the hex call returns aabbccddeeff00112233445566778899, then the byte array should look like this:

['0xaa','0xbb','0xcc','0xdd','0xee','0xff','0x00','0x11','0x22','0x33', '0x44', '0x55','0x66','0x77','0x88','0x99']

Here's an example JSON payload for the API:

{
  "end_device": {
    "ids": {
      "device_id": "test-device"
    },
    "session": {
      "keys": {
        "app_s_key": {
          "key": "32079314899832864415563434004158"
        }
      },
      "dev_addr": "3d72ba69"
    }
  },
  "field_mask": {
    "paths": [
      "ids.device_id",
      "session.keys.app_s_key.key",
      "session.dev_addr"
    ]
  }
}

and here's what the device configuration should look like:

ttn_config = {
    "devaddr": bytearray([0x3d, 0x72, 0xba, 0x69]),
    "nwkey": bytearray([]),
    "app": bytearray([0x32, 0x07, 0x93, 0x14, 0x89, 0x98, 0x32, 0x86, 0x44, 0x15, 0x56, 0x34, 0x34, 0x00, 0x41, 0x58])
    "country": "EU",
}

Is there a an easy way that I'm missing to convert between the two formats?

What I'm trying to do is convert a string like "abcd" into bytes that represent the hexadecimal of the string oxabcd. Python keeps telling me OverflowError: int too big to convert

The code is the following:

a = "abcd"

print(int(a, 16).to_bytes())

The error in full is:

Traceback (most recent call last):
  File "/home/repl109/main.py", line 6, in <module>
    print(int(a, 16).to_bytes())
        ^^^^^^^^^^^^^^^^^^^^^
OverflowError: int too big to convert

Anyone know a way to do this for large integers?