🚀 go-pugleaf

phr@telebit.com (Paul Rubin) writes:

>A co-worker of mine brought up an interesting idea.
>He thinks it might be very difficult to intercept data
>by tapping a phone line of someone using a modern high
>speed full duplex modem.  The reason is that the full
>available bandwidth of the phone line is being used
>in both directions; the modems separate out the signals
>with echo cancellation, which means that the modem
>takes the phone signal and subtracts what it itself
>is sending--the difference is what the other modem
>is sending.  But a wiretapper might have an awfully
>hard time of separating the two signals.  

>Any thoughts?

>Sci.crypt is probably not the right place for this,
>but I felt people here might be interested in the idea.
I wouldn't think that it would be too difficult for someone such
as the NSA to do something like that.