On Channel Transforms to Enhance Reciprocity and Quantization in Physical-Layer Secret Key Generation

Ensuring reliable and secure communications in the increasingly pervasive beyond <inline-formula> <tex-math notation="LaTeX">$5{^{\text {th}}}$ </tex-math></inline-formula> generation (B5G) wireless networks is one of the key research challenges. Within the physical...

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Main Authors: Ghalib Hussain, Syed Junaid Nawaz, Shurjeel Wyne, Mohammad N. Patwary
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Access
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Online Access:https://ieeexplore.ieee.org/document/10816322/
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author Ghalib Hussain
Syed Junaid Nawaz
Shurjeel Wyne
Mohammad N. Patwary
author_facet Ghalib Hussain
Syed Junaid Nawaz
Shurjeel Wyne
Mohammad N. Patwary
author_sort Ghalib Hussain
collection DOAJ
description Ensuring reliable and secure communications in the increasingly pervasive beyond <inline-formula> <tex-math notation="LaTeX">$5{^{\text {th}}}$ </tex-math></inline-formula> generation (B5G) wireless networks is one of the key research challenges. Within the physical layer security (PLS) paradigm, the secret key generation (SKG) technique exploits the wireless channel&#x2019;s randomness to generate symmetric secret keys for message encryption/decryption by legitimate communication nodes. The SKG procedure involves various steps such as wireless channel probing, quantization, information reconciliation, and privacy amplification to render effective symmetric secret key bits. This work proposes a novel multi-level channel quantization scheme, which for the given distribution of the channel envelopes&#x2019; gain, ensures an identical likelihood of the envelope samples falling into each quantization interval. Inspired by the classical companding transform (CT), the proposed probability integral transform (PIT)&#x2013;based quantization scheme works in three sequential steps. First, average contiguous duration (ACD), a second-order fading statistics metric, is considered to select and bias the channel samples that are more likely to fall in the same quantization interval. Subsequently, by using an invertible transform the envelope values are transformed into samples drawn from a uniform distribution, which are then processed through a uniform quantizer. The proposed PIT-based transformation and quantization scheme aims to enhance the trade-offs between the SKG performance metrics namely the key generation rate (KGR), key disagreement rate (KDR), and the key randomness properties. A comprehensive performance analysis of the proposed PIT-based quantization scheme for generalized gamma (GG) fading channels is conducted and its performance is evaluated in relation to several channel and system parameters. Moreover, a comparative analysis of the proposed scheme with its counterparts in the literature is also provided to demonstrate its relative performance gains, where our proposed scheme is observed to outperform the existing schemes. Notably, when the correlation of the reciprocal channel is set to <inline-formula> <tex-math notation="LaTeX">$\rho =0.8$ </tex-math></inline-formula>, the samples excursion qualification threshold is set to <inline-formula> <tex-math notation="LaTeX">$L=3$ </tex-math></inline-formula>, and GG fading conditions set as defined by <inline-formula> <tex-math notation="LaTeX">$\alpha =2$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$\xi =1$ </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">$\upsilon =1$ </tex-math></inline-formula>, the proposed algorithm, which employs sample biasing and transformation, offers an average improvement of 0.02% in KGR and 0.15% in KDR performance compared to the conventional UQ scheme. Additionally, the algorithm demonstrates superior performance in all considered eight the National Institute of Standards and Technology (NIST) randomness tests, exemplified by an average P-value of 0.78 in the frequency monobit test. Furthermore, for the considered system and channel parameters the proposed algorithm provides an average improvement of 0.06% in KDR compared to cumulative distribution function (CDF)-based non-uniform quantization (CDF-NUQ).
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spelling doaj-art-1f9dd42c943d4d8dba27d8bd1fd9dbc42025-01-03T00:01:58ZengIEEEIEEE Access2169-35362025-01-011325627210.1109/ACCESS.2024.352310510816322On Channel Transforms to Enhance Reciprocity and Quantization in Physical-Layer Secret Key GenerationGhalib Hussain0https://orcid.org/0000-0002-1425-316XSyed Junaid Nawaz1https://orcid.org/0000-0001-5448-2170Shurjeel Wyne2https://orcid.org/0000-0001-9532-2288Mohammad N. Patwary3https://orcid.org/0000-0003-2878-5295Department of Electrical and Computer Engineering, COMSATS University Islamabad (CUI), Islamabad, PakistanDepartment of Electrical and Computer Engineering, COMSATS University Islamabad (CUI), Islamabad, PakistanDepartment of Electrical and Computer Engineering, COMSATS University Islamabad (CUI), Islamabad, PakistanFaculty of Science and Engineering, University of Wolverhampton, Wolverhampton, U.K.Ensuring reliable and secure communications in the increasingly pervasive beyond <inline-formula> <tex-math notation="LaTeX">$5{^{\text {th}}}$ </tex-math></inline-formula> generation (B5G) wireless networks is one of the key research challenges. Within the physical layer security (PLS) paradigm, the secret key generation (SKG) technique exploits the wireless channel&#x2019;s randomness to generate symmetric secret keys for message encryption/decryption by legitimate communication nodes. The SKG procedure involves various steps such as wireless channel probing, quantization, information reconciliation, and privacy amplification to render effective symmetric secret key bits. This work proposes a novel multi-level channel quantization scheme, which for the given distribution of the channel envelopes&#x2019; gain, ensures an identical likelihood of the envelope samples falling into each quantization interval. Inspired by the classical companding transform (CT), the proposed probability integral transform (PIT)&#x2013;based quantization scheme works in three sequential steps. First, average contiguous duration (ACD), a second-order fading statistics metric, is considered to select and bias the channel samples that are more likely to fall in the same quantization interval. Subsequently, by using an invertible transform the envelope values are transformed into samples drawn from a uniform distribution, which are then processed through a uniform quantizer. The proposed PIT-based transformation and quantization scheme aims to enhance the trade-offs between the SKG performance metrics namely the key generation rate (KGR), key disagreement rate (KDR), and the key randomness properties. A comprehensive performance analysis of the proposed PIT-based quantization scheme for generalized gamma (GG) fading channels is conducted and its performance is evaluated in relation to several channel and system parameters. Moreover, a comparative analysis of the proposed scheme with its counterparts in the literature is also provided to demonstrate its relative performance gains, where our proposed scheme is observed to outperform the existing schemes. Notably, when the correlation of the reciprocal channel is set to <inline-formula> <tex-math notation="LaTeX">$\rho =0.8$ </tex-math></inline-formula>, the samples excursion qualification threshold is set to <inline-formula> <tex-math notation="LaTeX">$L=3$ </tex-math></inline-formula>, and GG fading conditions set as defined by <inline-formula> <tex-math notation="LaTeX">$\alpha =2$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$\xi =1$ </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">$\upsilon =1$ </tex-math></inline-formula>, the proposed algorithm, which employs sample biasing and transformation, offers an average improvement of 0.02% in KGR and 0.15% in KDR performance compared to the conventional UQ scheme. Additionally, the algorithm demonstrates superior performance in all considered eight the National Institute of Standards and Technology (NIST) randomness tests, exemplified by an average P-value of 0.78 in the frequency monobit test. Furthermore, for the considered system and channel parameters the proposed algorithm provides an average improvement of 0.06% in KDR compared to cumulative distribution function (CDF)-based non-uniform quantization (CDF-NUQ).https://ieeexplore.ieee.org/document/10816322/6Gbeyond 5Gkey bitsphysical layer securityquantizationsecret key generation
spellingShingle Ghalib Hussain
Syed Junaid Nawaz
Shurjeel Wyne
Mohammad N. Patwary
On Channel Transforms to Enhance Reciprocity and Quantization in Physical-Layer Secret Key Generation
IEEE Access
6G
beyond 5G
key bits
physical layer security
quantization
secret key generation
title On Channel Transforms to Enhance Reciprocity and Quantization in Physical-Layer Secret Key Generation
title_full On Channel Transforms to Enhance Reciprocity and Quantization in Physical-Layer Secret Key Generation
title_fullStr On Channel Transforms to Enhance Reciprocity and Quantization in Physical-Layer Secret Key Generation
title_full_unstemmed On Channel Transforms to Enhance Reciprocity and Quantization in Physical-Layer Secret Key Generation
title_short On Channel Transforms to Enhance Reciprocity and Quantization in Physical-Layer Secret Key Generation
title_sort on channel transforms to enhance reciprocity and quantization in physical layer secret key generation
topic 6G
beyond 5G
key bits
physical layer security
quantization
secret key generation
url https://ieeexplore.ieee.org/document/10816322/
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AT syedjunaidnawaz onchanneltransformstoenhancereciprocityandquantizationinphysicallayersecretkeygeneration
AT shurjeelwyne onchanneltransformstoenhancereciprocityandquantizationinphysicallayersecretkeygeneration
AT mohammadnpatwary onchanneltransformstoenhancereciprocityandquantizationinphysicallayersecretkeygeneration