"The idea of Switzerland (released in alpha under GPL
3.0) is simple. You install the client on two computers, and set up
a Switzerland server on a third. The EFF is providing a public
Switzerland server to get people started. Then you send traffic
back and forth between the two client machines. Each of them sends
a hashed summary of the traffic it sees to the server. If the
server notices a difference, that's pretty good evidence that
someone between point A and point B is tampering with the
traffic."