How to exchange sensitive data with ports?

[Elena Garrulo]

Hello,

I'd like to access smart cards from Erlang. Since there is not
dedicated module, I'll have to use C for that.

In this thread:

http://groups.google.com/group/erlang-programming/browse_frm/thread/f27c205eab2e8f95/2ac047fd8840cc2f?lnk=gst&q=ffi#2ac047fd8840cc2f

it is recommended that you use ports (that is: external processes) to
exchange data with native libraries.

However, the whole purpose of using smart cards is accessing sensitive
information stored into the card itself. To my limited knowledge,
opening a port (pipe) with an external process would allow sniffing.
Is that true? If not, what tools  should I use (preferably working
both on Linux and Windows)?

I apologize if the question is somewhat off-topic.

Thanks.