SkypeLine: Robust hidden data transmission for VoIP

Katharina Kohls, Dorothea Kolossa, Thorsten Holz, Christina Pöpper

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Internet censorship is used in many parts of the world to prohibit free access to online information. Different techniques such as IP address or URL blocking, DNS hijacking, or deep packet inspection are used to block access to specific content on the Internet. In response, several censorship circumvention systems were proposed that attempt to bypass existing filters. Especially systems that hide the communication in different types of cover protocols attracted a lot of attention. However, recent research results suggest that this kind of covert traffic can be easily detected by censors. In this paper, we present SkypeLine, a censorship circumvention system that leverages Direct-Sequence Spread Spectrum (DSSS) based steganography to hide information in Voice-over-IP (VoIP) communication. SkypeLine introduces two novel modulation techniques that hide data by modulating information bits on the voice carrier signal using pseudo-random, orthogonal noise sequences and repeating the spreading operation several times. Our design goals focus on undetectability in presence of a strong adversary and improved data rates. As a result, the hiding is inconspicuous, does not alter the statistical characteristics of the carrier signal, and is robust against alterations of the transmitted packets. We demonstrate the performance of Skype-Line based on two simulation studies that cover the theoretical performance and robustness. Our measurements demonstrate that the data rates achieved with our techniques substantially exceed existing DSSS approaches. Furthermore, we prove the real-world applicability of the presented system with an exemplary prototype for Skype.

Original languageEnglish (US)
Title of host publicationASIA CCS 2016 - Proceedings of the 11th ACM Asia Conference on Computer and Communications Security
PublisherAssociation for Computing Machinery, Inc
Pages877-888
Number of pages12
ISBN (Electronic)9781450342339
DOIs
StatePublished - May 30 2016
Event11th ACM Asia Conference on Computer and Communications Security, ASIA CCS 2016 - Xi'an, China
Duration: May 30 2016Jun 3 2016

Publication series

NameASIA CCS 2016 - Proceedings of the 11th ACM Asia Conference on Computer and Communications Security

Other

Other11th ACM Asia Conference on Computer and Communications Security, ASIA CCS 2016
CountryChina
CityXi'an
Period5/30/166/3/16

Keywords

  • Censorship circumvention
  • Covert communication
  • DSSS
  • Steganography
  • VoIP

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Computer Science Applications
  • Software

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