Exploiting Channel Diversity in Secret Key Generation from Multipath Fading Randomness

TL;DR

This paper presents a method to generate secret keys from wireless channel randomness by exploiting channel diversity, comparing CSI and RSSI-based methods, and designing LDPC code-based systems for improved key rates.

Contribution

It introduces a novel secret key generation approach leveraging multipath channel diversity and designs LDPC code systems for enhanced performance.

Findings

CSI-based key extraction achieves higher rates than RSSI-based methods.

Exploiting channel diversity significantly improves secret key generation.

LDPC codes enable efficient and reliable key generation at various SNR levels.

Abstract

We design and analyze a method to extract secret keys from the randomness inherent to wireless channels. We study a channel model for multipath wireless channel and exploit the channel diversity in generating secret key bits. We compare the key extraction methods based both on entire channel state information (CSI) and on single channel parameter such as the received signal strength indicators (RSSI). Due to the reduction in the degree-of-freedom when going from CSI to RSSI, the rate of key extraction based on CSI is far higher than that based on RSSI. This suggests that exploiting channel diversity and making CSI information available to higher layers would greatly benefit the secret key generation. We propose a key generation system based on low-density parity-check (LDPC) codes and describe the design and performance of two systems: one based on binary LDPC codes and the other (useful at higher signal-to-noise ratios) based on four-ary LDPC codes.