This project shows you how to sign an XML document with a PFX file (private and public key in one file)
Take a look at the bash script in SignXMLExample/DATA/generate.sh this will create a private key, a certificate then combine both into a PFX file. This is the only file used through out the demo.
This is just a basic example, please run at your own risk. I am not liable for any problems that might occur.