High-Rate Secret Key Generation Using Physical Layer Security and
Physical Unclonable Functions
Abstract
Physical layer security (PLS) can be adopted for efficient key sharing
in secured wireless systems. The random nature of the wireless channel
and channel reciprocity (CR) are the main pillars for realizing PLS
techniques. However, for applications that involve air-to-air (A2A)
transmission, such as unmanned aerial vehicle (UAV) applications, the
channel does not generally have sufficient randomness to enable reliable
key generation. Therefore, this work proposes a novel system design to
mitigate the channel randomness constraint and enable high-rate secret
key generation (SKG) process. The proposed system integrates physically
unclonable functions (PUFs) and CR principle to securely exchange secret
keys between two nodes. Moreover, an adaptive and controllable
artificial fading (AF) level with interleaving is used to mitigate the
impact of low randomness variations in the wireless channel. The
proposed system can operate efficiently even when the channel is nearly
flat or time invariant. Consequently, the time required for generating
and sharing a key is significantly shorter than conventional techniques.
We also propose a novel bit extraction scheme that reduces the number of
overhead bits required to share the intermediate keys. The obtained
Monte Carlo simulation results show that a key agreement can be reached
at the first trial for moderate and high signal-to-noise ratios (SNRs),
which is substantially faster than other PLS techniques. Moreover, the
results show that inducing AF into static channels reduces the mismatch
ratio between the generated secret sequences and degrades the
eavesdropper’s capability to predict the secret keys.