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Hiding Secret Messages In Skype Silences
Orome1 writes "A group of researchers from the Institute of Telecommunications of the Warsaw University of Technology have devised a way to send and receive messages hidden in the data packets used to represent silences during a Skype call. After learning that Skype transmits voice data in 130-byte packets and the silences in 70-byte packets, the researchers came upon the idea of using the latter to conceal the sending and receiving of additional messages."
If you are going to hide something, don't let everyone know where you put it.
Now that the exploit has been discussed it will be watched out for.
Don't know something? Look it up. Still don't know? Then ask.
UDP overhead is 28 bytes for ipv4. Add in overhead for the audio codec to represent a timeframe for a sound and 70 bytes become reasonable.
Exactly what I was thinking.
You would think that a packet specifying X seconds of simulated silence could be packed into a few bits, so maybe two bytes should suffice.
Were you planning on sending that "two seconds of silence" packet at the _start_ of the pause? If so I know a few theoretical physicists and at least one state lottery commission who would _love_ to see your algorithm.
Btw, Silence is a sound for computers which is represented by a flat line or basically the value of 0. Not getting packets and getting a value of 0 are different things whereas the former can be due to packet lost and broken connection while the latter is an actual value.
If it were "undetectable", it wouldn't be able to be spotted by the *receiver* either.
It may well be *innocuous*, but 'undetectable communications' are about as useful as 'unbreakable encryption', and every bit as oximoronic.