You have data that is sensitive, you can "Scramble" it in File Format and send within a Container Field. Scambling requires both Authorized Users to have the same "key" to Unscramble it. Then "key" security becomes a problem.
I have been more concerned about Security of those who are Authorized than a so called "interception" of IP protocol. I would call FileMaker directley on that issue of "interception".
Thanks for the post Jim. I will see what else I can find on the isue of interception. D