LuxSteg: First Practical Implementation of Steganography in VLC

Visible-light communication (VLC) is a new technique for high-speed, low-cost wireless data transmission services. One of the areas in which VLC is considered superior to traditional radio-based communication is security. The common slogan summarizing the VLC security features is WYSIWYS- “What You See Is What You Send.”However, the broadcast nature of downlink VLC makes it possible for eavesdroppers to easily intercept the light communication in various settings, e.g., offices, conference rooms, plenum spaces, and so on. Similarly to radio-based data broadcasting systems, such as Wi-Fi, VLC opens the possibilities of hiding information in the public channel. In this paper, we describe (for the first time, to the best of our knowledge) the implementation of steganographic data transmission in a VLC system called LuxSteg. This VLC system utilizes pulse position modulation and direct sequence-code division multiple access modulation. In our implementation, multiple steganographic data streams are mixed with the spreading codes and combined with the overt data stream. We achieve a steganographic transmission rate of approximately 1 Mb/s hidden in a 110-Mb/s data stream. We analyze the influence of the spreading factor, spreading code type, number of hidden data streams, and the amplitude on the achievable transmission rate, undetectability, and robustness.