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Quantum cryptography is the study of unconditional information security against an all-powerful eavesdropper in secret key distillation. However, the assumption of an omnipotent eavesdropper is too strict for some realistic implementations. In this paper, we study the realistic application model of secret key distillation over a satellite-to-satellite free-space channel in which we impose a reasonable restriction on the eavesdropper by setting an exclusion zone around the legitimate receiver as a defense strategy. We first study the case where the eavesdropper’s aperture size is unlimited so their power is only restricted by the exclusion zone. Then, we limit Eve’s aperture to a finite size and study the straightforward case when her aperture is in the same plane of Bob’s, investigating how an exclusion zone can help improve security. Correspondingly, we determine the secret key rate lower bounds as well as upper bounds. Furthermore, we also apply our results on specific discrete variable (DV) and continuous variable (CV) protocols for comparison. We show that, by putting reasonable restrictions on the eavesdropper through the realistic assumptions of an inaccessible exclusion zone, we can significantly increase the key rate in comparison to those without and do so with relatively lower transmission frequency. We conclude that this model is suitable for extended analysis in many light-gathering scenarios and for different carrier wavelengths.
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Security in Terahertz WLANs with Leaky Wave Antennas
This paper presents the first security study of THz networks with Leaky Wave Antennas (LWAs). We employ a mix of analytical models and over-the-air experiments to explore the unique security properties of LWA links. We show via both models and experiments that the LWA’s angle-frequency coupling leads to non-uniform secrecy capacity across sub-channels yielding advantages to an eavesdropper at edge frequencies. Yet, because different frequencies emit energy at different angles, the eavesdropper is thwarted from easily intercepting an entire wideband transmission. The experiments diverge from the analytical model in that the model underpredicts the eavesdropper’s advantage at angles smaller than the target user and subsequent asymmetric performance across angles. Nonetheless, both the model and measurements show that increasingly wide bandwidth and correspondingly wide beams have only a modest marginal security penalty.
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- Award ID(s):
- 1923733
- PAR ID:
- 10169053
- Date Published:
- Journal Name:
- Proceedings of the 13th ACM Conference on Security and Privacy in Wireless and Mobile Networks (WiSec)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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