Sign a soap message from a JKS using Python/jython in Unix

I am currently calling a Data Power webservice using Curl command from unix .

I have a requirement that I have to dynamically message sign the soap request every time I make a call to the webservice using my JKS certificate . My private key is present in my JKS file kept at the same location.

How can I perform this action in Unix ? Do I need to do it through Jython , if yes? Can you please give me some example.