Blind Detection of Spread Spectrum Flow Watermarks

— Recently, the direct sequence spread-spectrum (DSSS)-based technique has been proposed to trace anonymous network flows. In this technique, homogeneous pseudo-noise (PN) codes are used to modulate multiple-bit signals that are embedded into the target flow as watermarks. This technique could be maliciously used to degrade an anonymous communication network. In this paper, we propose a simple single flow-based scheme to detect the existence of these watermarks. Our investigation shows that even if we have no knowledge of the applied PN code, we are still able to detect malicious DSSS watermarks via mean-square autocorrelation (MSAC) of a single modulated flow’s traffic rate time series. MSAC shows periodic peaks due to self-similarity in the modulated traffic caused by homogeneous PN codes that are used in modulating multiple-bit signals. Our scheme has low complexity and does not require any PN-code synchronization. We evaluate this detection scheme’s effectiveness via si...

• Type: Conference
• Year: 2009
• Where: INFOCOM
• Authors: Weijia Jia, Fung Po Tso, Zhen Ling, Xinwen Fu, Dong Xuan, Wei Yu
• Keywords: Communications, Dsss Watermark, INFOCOM 2009, Malicious Dsss Watermarks, Pn Codes