The-art-of-invisibility-_-the-world’s-most-famous-hacker-teaches-you-how-to-be-safe-in-the-age-of-Bi

allows access to anyy record of a specific call, law enforcement would in this
case onlyy see the encryypted traffic across the mobile carrier’s line, which
would be unintelligible. And Open Whisper Syystems, the nonprofit
organization that makes Signal, does not have the keyys, so a warrant would
be useless. The keyys exist onlyy on the devices at either end of the call. And
once the call ends, those session keyys are destroyyed.
Currentlyy CALEA does not extend to end users or their devices.
You might think that having encryyption on yyour cell phone would drain
yyour batteryy. It does, but not byy much. Signal uses push notifications, as do
the apps WhatsApp and Telegram. Thus yyou onlyy see a call when it is
incoming, which cuts down on batteryy use while yyou’re listening for new
calls. The Android and iOS apps also use audio codecs and buffer
algorithms native to the mobile network, so again the encryyption is not
draining a lot of power while yyou’re making a call.
In addition to using end-to-end encryyption, Signal also uses perfect
forward secrecyy (PFS). What is PFS? It’s a syystem that uses a slightlyy
different encryyption keyy for everyy call, so that even if someone does
manage to get hold of yyour encryypted phone call and the keyy that was used
to encryypt it, yyour other calls will remain secure. All PFS keyys are based on
a single original keyy, but the important thing is that if someone
compromises one keyy, it doesn’t mean yyour potential adversaryy has access
to yyour further communications.