Best way to transfer data between a CF webservice and a VB6 application

I am trying to find the best way to transfer data between a CF webservice and a VB6 application. The data needs to be secure when being transfered. I was thinking about using XML but i don’t know much on how to make it secure. I have heard of WS security but havn’t really used it. If anyone has any suggestions/ideas that would be great. Thanks.