Wei, ZhuangkunGuo, WeisiLi, Bin2022-04-142022-04-142022-04-11Wei Z, Guo W, Li B. (2022) A multi-eavesdropper scheme against RIS secured LoS-dominated channel, IEEE Communications Letters, Volume 26, Number 6, June 2022, pp. 1221-12251089-77981558-2558https://doi.org/10.1109/LCOMM.2022.3166239https://dspace.lib.cranfield.ac.uk/handle/1826/17770Reconfigurable intelligent surface (RIS) has been shown as a promising technique to increase the channel randomness for secret key generation (SKG) in low-entropy channels (e.g., static or line-of-sight (LoS)), without small-scale fading. In this letter, we show that even with the aid of RIS, collaborative eavesdroppers (Eves) can still estimate the legitimate Alice-Bob channel and erode their secret key rates (SKRs), since the RIS induced randomness is also reflected in the Eves’ observations. Conditioned on Eves’ observations, if the entropy of RIS-combined legitimate channel is zero, Eves are able to estimate it and its secret key. Leveraging this, we design a multi-Eve scheme against the RIS-secured LoS dominated scenarios, by using the multiple Eves’ observations to reconstruct the RIS-combined legitimate channel. We further deduce a closed-form secret key leakage rate under our designed multi-Eve scheme, and demonstrate the results via simulations.enAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/Physical layer secret keyreconfigurable intelligent surfaceeavesdroppingstatic channelwireless communicationsArticle