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."

Comments

Go old school rather than packet level?

[Keruo]

If you talk long conversation, specific pauses might simply work as morse code.

There goes that idea

[Jeng]

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.

Move Along

[Anonymous Coward]

Nothing to see hear.

Re:Eloquent silence

[hawguy]

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.

Clearly there is something else going on, or they would not have designed such a large packet to "represent silence".
That one can distinguish the silence packets from the voice packets doesn't speak too well of the encryption that Skype has always claimed they use.

If the Skype client didn't send packets during 'silence', then the client on the receiving end of an extended silent session wouldn't know whether there was silence on the other end or a network problem. That's why the client keeps sending packets even during "silence" rather than just timing silent sections then sending out a packet at the end of the silence saying "It was silent for the past 10 seconds, so that's why you didn't receive any data from me".

Re:Eloquent silence

[Minwee]

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.

Whitespace!

[Vlad_the_Inhaler]

C may currently have overtaken Java as the most popular language but Whitespace is going to overtake them all!