Information steganography using backscatter radio

Summarization: Recent advances in ambient, FM backscatter radio showed the feasibility of piggybacking 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 covert communication. 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 equipped with FM radio, acting as the receiver. A Linear Feedback Shift Register (LFSR), provided with a key completely determining its output, generates the symbol sequences that serve as spreading sequences in DSSS, thus adding a Private-Key Encryption layer to enhance the cryptosystem's robustness. A Repetition Code is utilized as a way of error correction to increase the per- formance. Besides simulations, a prototype was implemented to verify the feasibility of the proposed concept