Bitmap-based Steganographic Handshake and Hidden Communication in BitTorrent Network

In BitTorrent network, the bitmap is used to indicate the state of data blocks of file owned by a peer. Before the downloading of the file starts, the file provider first sends its corresponding bitmap to the requester to show which data blocks it owns. This provides the possibility for hiding the identity information in the bitmap and exchanging the identity information secretly. In this paper, we propose a bitmap-based steganographic handshake approach and implement a prototype system based on the BitTorrent network. In our prototype system, the network can operate normally. More importantly, hidden peers successfully exchange their identity information and accurately identify the other hidden peers without being detected by the regular peers. (C) 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.