The security of link signature: A view from channel models

Link signature (LS) provides security to wireless devices by exploiting multipath characteristics, with an essential assumption that half-wavelength separation is sufficient to prevent nearby adversary sensors from effectively inferring the legitimate LS. However, such an assumption may be too optimistic; high channel correlation has been observed in real world experiments even when the spatial separation is much larger than half-wavelength. In fact, channel correlation varies for different wireless environments. Considering this, various well-established channel correlation models are investigated in this work and a set of physical factors that have significant influence on link signature security are identified. With the obtained insights, we build a generic channel correlation model for LS security assessment in various wireless environments of interest. Numerical experiments are conducted to explore corresponding guard zone designs.