An Information Theoretic Analysis of Ghost Modulation

TL;DR

This paper provides a theoretical analysis of Ghost Modulation, a covert communication scheme using existing network streams, focusing on channel modeling, decision rules, synchronization, and error rate performance.

Contribution

It introduces a mathematical framework for Ghost Modulation, including channel models, decision algorithms, and simulation results, advancing understanding of its technical capabilities.

Findings

Mathematical description of GM signal and channel models

Proposed maximum-likelihood decision rule for GM

Simulation results showing BER performance of GM

Abstract

Side channels have become an essential component of many modern information-theoretic schemes. The emerging field of cross technology communications (CTC) provides practical methods for creating intentional side channels between existing communications technologies. This paper describes a theoretical foundation for one such, recently proposed, CTC scheme: Ghost Modulation (GM). Designed to modulate a low-data-rate message atop an existing network stream, GM is particularly suited for transmitting identification or covert information. The implementation only requires firmware updates to existing hardware, making it a cost-effective solution. However, GM provides an interesting technical challenge due to a highly asymmetric binary crossover erasure channel (BCEC) that results from packet drops and network delays. In this work, we provide a mathematical description of the signal and channel models for GM. A heuristic decision rule based on maximum-likelihood principles for simplified channel models is proposed. We describe an algorithm for GM packet acquisition and timing synchronization, supported by simulation results. Several well known short block codes are applied, and bit error rate (BER) results are presented.