The Research On Information Hiding Based On BitTorrent Network

Information hiding has been a new hotspot for the research of information security in the network age. It has a lot of potential applications such as copyright protection of digital media, steganography and hidden communication. Among various types of transmission channels, network is most widely used in modern communication. Hence it is worthy conducting deep investigation into the techniques of network information hiding. In network information hiding field, current researches mainly concentrated on Internet, LAN, and WLAN. BitTorrent network, as a rising and widely used P2P network transmitting a huge number of data everyday, is an ideal carrier host for steganography, but few contributions has been made on information hiding aiming at BitTorrent network. This paper is focused on the steganographic schemes in BitTorrent network.For the processes of information release and file sharing in the BitTorrent network, we, in this thesis, propose three steganographic algorithms, which are separately based on the Torrent file, bitfield message and piece selection scheme of the BitTorrent network. After analyzing the Torrent file, we design two algorithms for it, namely the steganographic algorithm of letter case change and optional field reusage. The letter case change algorithm, which is based on the insensitivity of letter case, hides information by modifying the written states of the URL. This method does not enlarge the carrier host and has the merit of good imperceptibility. The optional field resuage algorithm uses the redundancy in the structure of Torrent file to embed secret message by adding or modifying the optional fields. This approach has larger embedding capacity. The steganographic algorithm based on Bitfield adopts the bitfield message which used to communicate among peers in BitTorrent network as carrier host, and imports matrix encoding technology for hiding secret message, it has preferable imperceptibility. In order to improve the capacity, an information hiding algorithm based on pieces selection scheme of"Rarest First"is presented. It achieves hidden communication by the"have message"and"piece message"which are used for communication in peers.Extensive experiments have been conducted to prove the efficiency and reliability of our algorithms. The experimental results show that our algorithms have preferable performance for hidden communication in BitTorrent network.