How to generate current_device_password for /api/v1/devices/assign?

How can I generate the current_device_password field needed for auto-assigning a device?

I am writing my own linux auto assign tool and I need to fill in current_device_password to complete the fields for /api/v1/devices/assign API call which is undocumented, but it's used in the official auto assignment tool. current_device_password is the same you can find in AssignmentData.json.

Which password is it and how is it hashed/encrypted?