Experimental Study on Key Generation for Physical Layer Security in Wireless Communications

This paper presents a thorough experimental study on key generation principles, i.e., temporal variation, channel reciprocity, and spatial decorrelation, through a testbed constructed by using wireless open-access research platform. It is the first comprehensive study through: 1) carrying out a number of experiments in different multipath environments, including an anechoic chamber, a reverberation chamber, and an indoor office environment, which represents little, rich, and moderate multipath, respectively; 2) considering static, object moving, and mobile scenarios in these environments, which represents different levels of channel dynamicity; and 3) studying two most popular channel parameters, i.e., channel state information and received signal strength. Through results collected from over a hundred tests, this paper offers insights to the design of a secure and efficient key generation system. We show that multipath is essential and beneficial to key generation as it increases the channel randomness. We also find that the movement of users/objects can help introduce temporal variation/randomness and help users reach an agreement on the keys. This paper complements existing research by experiments constructed by a new hardware platform

Impact of Realistic Propagation Conditions on Reciprocity-Based Secret-Key Capacity

Secret-key generation exploiting the channel reciprocity between two legitimate parties is an interesting alternative solution to cryptographic primitives for key distribution in wireless systems as it does not rely on an access infrastructure and provides information-theoretic security. The large majority of works in the literature generally assumes that the eavesdropper gets no side information about the key from her observations provided that (i) it is spaced more than a wavelength away from a legitimate party and (ii) the channel is rich enough in scattering. In this paper, we show that this condition is not always verified in practice and we analyze the secret-key capacity under realistic propagation conditions

A Survey of Physical Layer Security Techniques for 5G Wireless Networks and Challenges Ahead

Physical layer security which safeguards data confidentiality based on the information-theoretic approaches has received significant research interest recently. The key idea behind physical layer security is to utilize the intrinsic randomness of the transmission channel to guarantee the security in physical layer. The evolution towards 5G wireless communications poses new challenges for physical layer security research. This paper provides a latest survey of the physical layer security research on various promising 5G technologies, including physical layer security coding, massive multiple-input multiple-output, millimeter wave communications, heterogeneous networks, non-orthogonal multiple access, full duplex technology, etc. Technical challenges which remain unresolved at the time of writing are summarized and the future trends of physical layer security in 5G and beyond are discussed.Comment: To appear in IEEE Journal on Selected Areas in Communication

Secret Key Generation Schemes for Physical Layer Security

Physical layer security (PLS) has evolved to be a pivotal technique in ensuring secure wireless communication. This paper presents a comprehensive analysis of the recent developments in physical layer secret key generation (PLSKG). The principle, procedure, techniques and performance metricesare investigated for PLSKG between a pair of users (PSKG) and for a group of users (GSKG). In this paper, a detailed comparison of the various parameters and techniques employed in different stages of key generation such as, channel probing, quantisation, encoding, information reconciliation (IR) and privacy amplification (PA) are provided. Apart from this, a comparison of bit disagreement rate, bit generation rate and approximate entropy is also presented. The work identifies PSKG and GSKG schemes which are practically realizable and also provides a discussion on the test bed employed for realising various PLSKG schemes. Moreover, a discussion on the research challenges in the area of PLSKG is also provided for future research

CSI-based versus RSS-based Secret-Key Generation under Correlated Eavesdropping

Physical-layer security (PLS) has the potential to strongly enhance the overall system security as an alternative to or in combination with conventional cryptographic primitives usually implemented at higher network layers. Secret-key generation relying on wireless channel reciprocity is an interesting solution as it can be efficiently implemented at the physical layer of emerging wireless communication networks, while providing information-theoretic security guarantees. In this paper, we investigate and compare the secret-key capacity based on the sampling of the entire complex channel state information (CSI) or only its envelope, the received signal strength (RSS). Moreover, as opposed to previous works, we take into account the fact that the eavesdropper's observations might be correlated and we consider the high signal-to-noise ratio (SNR) regime where we can find simple analytical expressions for the secret-key capacity. As already found in previous works, we find that RSS-based secret-key generation is heavily penalized as compared to CSI-based systems. At high SNR, we are able to precisely and simply quantify this penalty: a halved pre-log factor and a constant penalty of about 0.69 bit, which disappears as Eve's channel gets highly correlated

Skema Secret Key Generation (SKG) untuk Keamanan pada Sistem Komunikasi di Lingkungan Wireless

Skema Secret Key Generation (SKG) yang mengeksploitasi sifat reciprocity dan keacakan kanal wireless untuk membangkitkan secret key telah menjadi area penelitian yang semakin menarik dan menjanjikan. Terdapat 3 permasalahan utama dalam pembangunan skema SKG yang efisien yang harus diatasi, yaitu trade-off antara parameter performansi Key Disagreement Rate (KDR) dan Key Generation Rate (KGR), tingginya kompleksitas implementasi karena banyaknya tahapan yang harus dilalui, serta tidak efisiennya skema SKG yang dibangun sehingga tidak sesuai jika diimplementasikan pada perangkat Internet of Things(IoT) yang memiliki keterbatasan sumber daya. Disertasi ini berkontribusi dalam mengatasi ketiga permasalahan tersebut. Kontribusi pertama yang dilakukan untuk mengatasi trade-off antara parameter performansi KDR dan KGR adalah didapatkannya kombinasi yang optimal antara metode pra proses yaitu Kalman Filter, Modified Polynomial Regression (MPR), serta Savitzky Golay Filter dan kuantisasi multilevel. Hasil yang didapat adalah penurunan KDR dan peningkatan KGR dibandingkan dengan skema yang eksisting. Kontribusi kedua dari disertasi ini adalah mekanisme penyederhanaan skema SKG dengan kombinasi metode Modified Kalman (MK) serta Combined Multilevel Quantization (CMQ) sehingga bisa dihasilkan secret key yang identik tanpa melalui tahap rekonsiliasi informasi. Hasil pengujian yang dilakukan menghasilkan 4 blok 128-bit data di lingkungan tanpa halangan serta 2 blok 128-bit data yang memiliki KDR sebesar 0 sehingga tidak memerlukan koreksi untuk mendapatkan secret key yang identik. Kontribusi ketiga dari disertasi ini adalah didapatkannya skema SKG Signal Strength Exchange (SSE) yang efisien dalam hal waktu komputasi dan overhead komunikasi dengan menggunakan metode Synchronized Quantization (SQ) sebagai bagian dari skema SKG SSE. Hasil yang didapat menunjukkan penurunan waktu komputasi menjadi sebesar 3.8% dan overhead komunikasi menjadi sebesar 34% skema yang eksisting. Kontribusi yang dihasilkan dalam disertasi ini diharapkan dapat menjadi salah satu solusi alternatif pembentukan kunci simetris yang tidak membutuhkan kompleksitas komputasi serta Trusted Third Party (TTP), sehingga cocok jika digunakan pada berbagai aplikasi IoT