SkyDe: a Skype-based Steganographic Method

Wojciech Mazurczyk, Maciej Karaś, Krzysztof Szczypiorski


This paper introduces SkyDe (Skype Hide), a new steganographic method that utilizes Skype encrypted packets with silence to provide the means for clandestine
communication. It is possible to reuse packets that do not carry voice signals for steganographic purposes because Skype does not use any silence suppression mechanism.
The method’s proof-of-concept implementation and first experimental results are presented. They prove that the method is feasible and offers steganographic bandwidth as high as 2.8 kbps.


Information hiding, network steganography, Skype

Full Text:



Mazurczyk, W. (2013); VoIP Steganography and Its Detection - A Survey, ACM Computing Surveys (accepted for publication), ISSN 0360-0300.

Mazurczyk, W.; Szczypiorski, K. (2008); Steganography of VoIP Streams, In Proc. of 3rd Int Symp Information Security (IS'08), Monterrey, Mexico, 1001-1018.

Huang, Y.; Tang, S.; Yuan, J. (2011); Steganography in Inactive Frames of VoIP Streams Encoded by Source Codec, IEEE Transactions on information forensics and security, ISSN 1556-6013, 6(2):296-306.

Wang, X., Chen, S., Jajodia, S. (2005); Tracking anonymous peer-to-peer VoIP calls on the internet, In Proc. of 12th ACM CCS '05, 81-91.

Caukin, J. (2012); 35 Million People Concurrently Online on Skype, Skype Big Blog, URL:

Lubacz, J.; Mazurczyk, W.; Szczypiorski, K. (2010); Vice over IP, IEEE Spectrum, ISSN 0018-9235, 40-45

Timberg, C.; Nakashima, E. (2012); Skype makes chats and user data more available to police, URL: skype-makes-chats-and-user-data-more-available-to-police/2012/07/25/ gJQAobI39W_story.html

Bonfiglio, D.; Mellia, M.; Meo, M.; Rossi, D.; Tofanelli, P. (2007);Revealing Skype traffic: when randomness plays with you, In Proc. of SIGCOMM '07, NY, USA, 37-48.

Bonfiglio, D.; Mellia, M.; Meo, M.; Ritacca, N.; Rossi, D. (2008); Tracking Down Skype Traffic, In Proc. of IEEE INFOCOM '08, Phoenix, USA.

Chang, Y.C.; Chen, K.T.; Wu, C.C.; Lei, C.-L. (2008); Inferring speech activity from encrypted Skype traffic, In Proc. of IEEE Globecom '08, Los Alamitos, USA, 1-5.

Molnar, S.; Perenyi, M. (2011); On the identification and analysis of Skype traffic, International Journal of Communication Systems, ISSN 1074-5351, 24(1):94-117.

Iwano, Y., Sugita, Y., Kasahara, Y., Nakazato, S., Shirai, K. (1997); Difference in visual information between face to face and telephone dialogues, In Proc. of IEEE ICASSP '97, 1499-1502.

Berger, J.; Hellenbart, A.; Weiss, B.; Moller, S.; Gustafsson, J.; Heikkila, G. (2008); Estimation of quality per call in modelled telephone conversations, In Proc. of IEEE ICASSP'08, 4809-4812.

Garofolo, J.S. et al. (1993); TIMIT Acoustic-Phonetic Continuous Speech Corpus Linguistic Data Consortium, Philadelphia, USA.

ITU-T (2001); Recommendation. P.862. Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs.

ITU-T (1996); Recommendation. P.800. Methods for subjective determination of transmission quality.

Hamdaqa, M.; Tahvildari, L. (2011); ReLACK: A Reliable VoIP Steganography Approach, In Proc. of 5th International Conference on Secure Software Integration and Reliability Improvement (SSIRI '11), Korea, 189-197.

ReLACK: A Reliable VoIP Steganography Approach, In Proc. of 5th International Conference on Secure Software Integration and Reliability Improvement (SSIRI '11), Korea, 189-197.

TeleGeography Report (2012); International Call Traffic Growth Slows as Skype's Volumes Soar, URL: international-call-traffic-growth-slows-as-skypes-volumes-soar/index.html

IEEE (2004); I. S. 802.16-2004, IEEE standard for local and metropolitan area networks part 16: Air interface for fixed broadband wireless access systems.

Wright, C.; Ballard, L.; Coulls, S.; Monrose, F.; Masson, G. (2008); Spot me if you can: recovering spoken phrases in encrypted VoIP conversations. In Proc. of IEEE Symposium on Security and Privacy, May, 2008


Copyright (c) 2017 Wojciech Mazurczyk, Maciej Karaś, Krzysztof Szczypiorski

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

CC-BY-NC  License for Website User

Articles published in IJCCC user license are protected by copyright.

Users can access, download, copy, translate the IJCCC articles for non-commercial purposes provided that users, but cannot redistribute, display or adapt:

  • Cite the article using an appropriate bibliographic citation: author(s), article title, journal, volume, issue, page numbers, year of publication, DOI, and the link to the definitive published version on IJCCC website;
  • Maintain the integrity of the IJCCC article;
  • Retain the copyright notices and links to these terms and conditions so it is clear to other users what can and what cannot be done with the  article;
  • Ensure that, for any content in the IJCCC article that is identified as belonging to a third party, any re-use complies with the copyright policies of that third party;
  • Any translations must prominently display the statement: "This is an unofficial translation of an article that appeared in IJCCC. Agora University  has not endorsed this translation."

This is a non commercial license where the use of published articles for commercial purposes is forbiden. 

Commercial purposes include: 

  • Copying or downloading IJCCC articles, or linking to such postings, for further redistribution, sale or licensing, for a fee;
  • Copying, downloading or posting by a site or service that incorporates advertising with such content;
  • The inclusion or incorporation of article content in other works or services (other than normal quotations with an appropriate citation) that is then available for sale or licensing, for a fee;
  • Use of IJCCC articles or article content (other than normal quotations with appropriate citation) by for-profit organizations for promotional purposes, whether for a fee or otherwise;
  • Use for the purposes of monetary reward by means of sale, resale, license, loan, transfer or other form of commercial exploitation;

    The licensor cannot revoke these freedoms as long as you follow the license terms.

[End of CC-BY-NC  License for Website User]

INTERNATIONAL JOURNAL OF COMPUTERS COMMUNICATIONS & CONTROL (IJCCC), With Emphasis on the Integration of Three Technologies (C & C & C),  ISSN 1841-9836.

IJCCC was founded in 2006,  at Agora University, by  Ioan DZITAC (Editor-in-Chief),  Florin Gheorghe FILIP (Editor-in-Chief), and  Misu-Jan MANOLESCU (Managing Editor).

Ethics: This journal is a member of, and subscribes to the principles of, the Committee on Publication Ethics (COPE).

Ioan  DZITAC (Editor-in-Chief) at COPE European Seminar, Bruxelles, 2015:

IJCCC is covered/indexed/abstracted in Science Citation Index Expanded (since vol.1(S),  2006); JCR2018: IF=1.585..

IJCCC is indexed in Scopus from 2008 (CiteScore2018 = 1.56):

Nomination by Elsevier for Journal Excellence Award Romania 2015 (SNIP2014 = 1.029): Elsevier/ Scopus

IJCCC was nominated by Elsevier for Journal Excellence Award - "Scopus Awards Romania 2015" (SNIP2014 = 1.029).

IJCCC is in Top 3 of 157 Romanian journals indexed by Scopus (in all fields) and No.1 in Computer Science field by Elsevier/ Scopus.


 Impact Factor in JCR2018 (Clarivate Analytics/SCI Expanded/ISI Web of Science): IF=1.585 (Q3). Scopus: CiteScore2018=1.56 (Q2);

SCImago Journal & Country Rank

Editors-in-Chief: Ioan DZITAC & Florin Gheorghe FILIP.