Use the symmetric passphrase to decrypt data.

And to decrypt the data on the receiving end type:

$ openssl enc -a -d -nosalt -aes-128-cbc -kfile passphrase-$$ \
		-out myPriv.xml -in myPriv.xml.aes128
		

Once decrypted the resulting myPriv.xml is now human readable and will require further processing by your backend systems. This process can be reversed for replies to web service requests.

Again if you are not planning to reuse the passphrase for subsequent transmissions then it is safer to remove it then to leave it on your system.

			$ rm passphrase-$$ passphrase-$$.sig passphrase-$$.sig.enc passphrase.sig.enc