Error: "BAD_DATA {invalid MAVLink CRC in msgID 42000 0xc139 should be 0x8d4d, [...]" in personal implementation in MAVLink

[frank rossi]

For university purposes, I am working on project about implementig confidenziality in MAVLink.

For this project, I have created my own custom dialect .xml:

I followed this guide for generated the personalized MAVLink dialect in pyhton.

After generetad the dialect, I used it. Below the script used:

• script gcs.py:
  
  
• script drone.py:
  
  

The issue I find is the apparance of the following error message (output of the gcs.py script):

I am also including the output of the other script:

How can I fix this problem? Thanks for the replies.

[Hamish Willee]

The message means what it says, that the calculated CRC_EXTRA (https://mavlink.io/en/guide/serialization.html#crc_extra) does not match what the recipient expected. This happens if your message definition does not match on both ends of the connection - i.e. you changed the name or type of a field, or added an extra field, or whatever.
It is unlikely to be directly caused by signing.

Assuming you're working with ArduPilot, I'd be asking specific question on their discussion boards.