There are several companies such as Semaphore Technologies that
provide encryption tools that will encrypt/decrypt IP on the fly.
If you use two such boxes, and allow IP to pass between them, you may
There are a number of variables in this equation,such as whether you
allow the two machines to talk to others within their respective
companies. If you do, then you must take great care to control the
environments of each of these machines. (I fully realize that you
would likely be directly responsible for only one end).