Channel-State-Information (CSI)-based Key Generation (KG) is an attractive technique for generating symmetric cryptographic keys due to low memory and processing power requirements. CSI-based KG protocols also promise high key rates for vehicular communication channels due to the rich entropy inherited in such dynamic channels. However, as a relatively new field, physical layer security is often limited to idealistic scenarios. The assumption that the channels decorrelate at a half-wavelength distance brings secrecy vulnerabilities that are quantified and brought to attention. This paper convinces that, even in rich scattering environments, the distance of half-wavelength is not perfectly secure, and it may be disastrous under non-idealistic antenna gain patterns. Aiming to bring CSI-based KG a step closer to practical implementation, this paper drops one of the most common idealistic assumptions in the field of PLS and redefines secure distance.
Original languageEnglish
Number of pages6
Publication statusPublished - 19 Jun 2022


  • CSI-based key generation
  • physical layer security
  • Rayleigh channels
  • spatial channel correlation


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