Athanasios Topalis, "Information steganography using backscatter radio", Diploma Work, School of Electrical and Computer Engineering, Technical University of Crete, Chania, Greece, 2019
https://doi.org/10.26233/heallink.tuc.83071
Recent advances in ambient, FM backscatter radio showed the feasibility ofpiggybacking an audio signal on top of a broadcast FM radio transmission.In conjunction with the weak transmission power inherent in backscatter ra-dio systems, this work exploits FM ambient backscatter to achieve covertcommunication. Information in the form of plain text is converted to a wide-band audio signal using Direct Sequence Spread Spectrum (DSSS) modula-tion, resulting in a noise-like audio signal undergoing Frequency Modulation(FM) before being backscattered to a conventional smart phone equippedwith FM radio, acting as the receiver. A Linear Feedback Shift Register(LFSR), provided with a key completely determining its output, generatesthe symbol sequences that serve as spreading sequences in DSSS, thus addinga Private-Key Encryption layer to enhance the cryptosystem's robustness. ARepetition Code is utilized as a way of error correction to increase the per-formance. Besides simulations, a prototype was implemented to verify thefeasibility of the proposed concept.