Invisible Flow Watermarks for Channels with Dependent Substitution, Deletion, and Bursty Insertion Errors
This addresses the need for secure network communication by improving watermarking against common network errors, though it is incremental as it builds on prior work by adding robustness to insertions and deletions.
The paper tackles the problem of designing robust and invisible flow watermarks for network security, presenting a scheme that uses quantization index modulation and error-correction coding to endure packet losses and insertions while maintaining invisibility, with experimental results showing robustness to network jitter, packet drops, and splits.
Flow watermarks efficiently link packet flows in a network in order to thwart various attacks such as stepping stones. We study the problem of designing good flow watermarks. Earlier flow watermarking schemes mostly considered substitution errors, neglecting the effects of packet insertions and deletions that commonly happen within a network. More recent schemes consider packet deletions but often at the expense of the watermark visibility. We present an invisible flow watermarking scheme capable of enduring a large number of packet losses and insertions. To maintain invisibility, our scheme uses quantization index modulation (QIM) to embed the watermark into inter-packet delays, as opposed to time intervals including many packets. As the watermark is injected within individual packets, packet losses and insertions may lead to watermark desynchronization and substitution errors. To address this issue, we add a layer of error-correction coding to our scheme. Experimental results on both synthetic and real network traces demonstrate that our scheme is robust to network jitter, packet drops and splits, while remaining invisible to an attacker.