I am using the Python AWS API. I would like to invoke a lambda function from client code, but I have not been able to find documentation on whether the payload sent during invocation is encrypted. 
Can someone watching the network potentially snoop on the AWS invocation payload? Or is the payload transmitted over a secure channel?
If you turn on the debug logging you should see how exactly is data transmitted. Or try netstat or Wireshark to see if it makes connection to port 443 rather than 80.
From my experience with boto3 and S3 (not Lambda) it uses HTTPS, which I would consider somewhat secure. I hope the certificates are verified...
Does Boto3 encrypt the payload during transmission when invoking a lambda function?