Extract Secrets from Wireless Channel: A New Shape-based Approach

TL;DR

This paper introduces Puzzle, a shape-based wireless channel key extraction method that is more robust against environmental noise and attacks than traditional amplitude-based techniques, demonstrated through SDR experiments.

Contribution

The paper proposes a novel shape-based approach for wireless secret key extraction, significantly improving robustness over existing amplitude-based methods.

Findings

63% reduction in bit mismatch rate compared to CSI-2bit

Robustness against environmental noise and local disturbances

Resilience to eavesdropper prediction attacks

Abstract

Existing secret key extraction techniques use quantization to map wireless channel amplitudes to secret bits. This pa- per shows that such techniques are highly prone to environ- ment and local noise effects: They have very high mismatch rates between the two nodes that measure the channel be- tween them. This paper advocates using the shape of the channel instead of the size (or amplitude) of the channel. It shows that this new paradigm shift is significantly ro- bust against environmental and local noises. We refer to this shape-based technique as Puzzle. Implementation in a software-defined radio (SDR) platform demonstrates that Puzzle has a 63% reduction in bit mismatch rate than the state-of-art frequency domain approach (CSI-2bit). Exper- iments also show that unlike the state-of-the-art received signal strength (RSS)-based methods like ASBG, Puzzle is robust against an attack in which an eavesdropper can pre- dict the secret bits using planned movements.