@article{DBLP:journals/corr/abs-0805-2938,
  author    = {Wojciech Mazurczyk and
               Krzysztof Szczypiorski},
  title     = {Steganography of VoIP streams},
  journal   = {CoRR},
  volume    = {abs/0805.2938},
  year      = {2008},
  ee        = {http://arxiv.org/abs/0805.2938},
  bibsource = {DBLP, http://dblp.uni-trier.de},
  abstract = {

In this paper, we circumscribe available steganographic techniques
that can be used for creating covert channels for VoIP (Voice over Internet
Protocol) streams. Apart from characterizing existing steganographic methods
we provide new insights by presenting two new techniques. First one is
network steganography solution and exploits free/unused fields of the RTCP
(Real-Time Control Protocol) and RTP (Real-Time Transport Protocol)
protocols. The second method provides hybrid storage-timing covert channel
by utilizing delayed audio packets. The results of the experiment, that was
performed, regardless of steganalysis, to estimate a total amount of data
that can be covertly transferred in VoIP RTP stream during the typical call,
are also included in this article.

  }
}