The open and broadcast nature of wireless channels makes eavesdropping possible, leading to the inherent problem of information leakage. Inherent problems should be solved by endogenous security functions. Accordingly, wireless security problems should be resolved by channel-based endogenous security mechanisms. Firstly, this paper analyzes the endogenous security principle of the physical-layer-secret-key method. Afterward, we propose a novel conjecture that in a fast-fading environment, there must exist wireless systems where the endogenous secret key rate can match the user data rate. Moreover, the conjecture is well founded by the instantiation validation in a wireless system with BPSK inputs from the perspectives of both theoretical analysis and simulation experiments. These results indicate that it is possible to accomplish the one-time pad via endogenous secret keys in wireless communication.
The open and broadcast nature of wireless channels makes eavesdropping possible, leading to the inherent problem of information leakage. Inherent problems should be solved by endogenous security functions. Accordingly, wireless security problems should be resolved by channel-based endogenous security mechanisms. Firstly, this paper analyzes the endogenous security principle of the physical-layer-secret-key method. Afterward, we propose a novel conjecture that in a fast-fading environment, there must exist wireless systems where the endogenous secret key rate can match the user data rate. Moreover, the conjecture is well founded by the instantiation validation in a wireless system with BPSK inputs from the perspectives of both theoretical analysis and simulation experiments. These results indicate that it is possible to accomplish the one-time pad via endogenous secret keys in wireless communication.
The open and broadcast nature of wireless channels leads to the inherent security problem of information leakage in wireless communication. We can utilize endogenous security functions to resolve this problem. The fundamental solution is channel-based mechanisms, like physical layer secret keys. Unfortunately, current investigations have not fully exploited the randomness of wireless channels, making secret key rates not high. Consequently, user data can be encrypted by reducing the data rate to match the secret key rate. Based on the analysis of the endogenous wireless security principle, we proposed that the channel-based endogenous secret key rate can nearly match the maximum data rate in the fast-fading environments. After that, we validated the proposition in an instantiation system with multiple phase shift keying (MPSK) inputs from the perspectives of both theoretical analysis and simulation experiments. The results indicate that it is possible to accomplish the onetime pad without decreasing the data rate via channel-based endogenous keys. Besides, we can realize high-speed endogenously secure transmission by introducing independent channels in the domains of frequency, space, or time. The conclusions derived provide a new idea for wireless security and promote the application of the endogenous security theory.
Due to the broadcast nature of wireless channels, wireless communication is vulnerable to eavesdropping, message modification, and node impersonation. Securing the wireless communication requires the shared secret keys between the communicating entities. Traditional security schemes rely on public key infrastructures and cryptographic algorithms to manage secret keys. Recently, many physical-layer-based methods have been proposed as alternative solutions for key generation in wireless networks. These methods exploit the inherent randomness of the wireless fading channel to generate secret keys while providing information-theoretical security without intensive cryptographic computations. This article provides an overview of the existing PHY-based key generation schemes exploiting the randomness of the wireless channels. Specifically, we first introduce the fundamental and general framework of the PHY-based key generation schemes and then categorize them into two classes: received-signal-strength-based and channel- phase-based protocols. Finally, we present a performance comparison of them in terms of key disagreement probability, key generation rate, key bit randomness, scalability, and implementation issues.
In this thesis, a new practical method to realize one-time pad perfect secrecy for wireless \ncommunication is presented. Most commonly used security methods are based on cryp- tographic \ntechniques employed at the upper layers of a wireless network. These methods basically rely on the \ncomputational hardness of some mathematical problems. This com- putational complexity is vulnerable \nin nature due to fast-growing computational power of hardware technology, yet not taking into \naccount the revolution of Quantum computing in further future. Another core problematic issue \nexists in symmetric security systems; there is a deadlock between securing the channel and \nestablishing the shared key. We need the key for securing the channel, on the other hand, for \nsharing the key we need a secure channel. \n \nTo address such vulnerabilities, Physical Layer Security (PLS) has been widely studied in recent \nyears. PLS schemes build on the idea of turning unpredictable and random wire- less channel \ncharacteristics into a source for information-theoretic security. Information- theoretic security \nitself, relies on Shannon’s pioneer work . Shannon, inspired by one-time pad, also known as Vernam \ncipher, theoretically showed that the only unconditional per- fect secrecy system is a one-time pad \nwith a key at least as random as the plaintext, i.e., a system that uses a different random key to \ncipher any new plaintext. In PLS key genera- tion methods, legitimate parties alternately send \nprobe signals and estimate Channel State Information (CSI) of common random channel and then \nconvert enough amount of these estimates to secure shared keys. To achieve perfect secrecy, the key \ngeneration methods must meet the key randomness and Key Generation Rate (KGR) requirements of \ntheir specific cryptographic applications. \n \nIn this research a new practical system for achieving unconditional perfect secrecy is presented. \nOur system uses channel phase as the probing parameter to fully benefit from its uniform \ndistribution over [0, 2π]. It also uses an encryption method based on modulo- \n2π addition of phase values which is the perfect counterpart of XOR addition in binary one-time \npad. Moreover, by intentionally perturbing the wireless channel in vicinity of the transceiver \nantenna based on RF-mirrors structure, it produces different random phase values in each channel \nprobing, much faster than the inherent channel variation would do, resulting in dramatically higher \nKGR than any wide-band PLS scheme presented so far and realizing true perfect secrecy. Most \nimportantly, the focus of this research is a detailed practical algorithm for implementing the \nsystem as well as empirical results which makes \nour system the first channel-phase-based PLS scheme implementation, reported so far.
The one-time pad (OTP) secure transmission relies on the random keys to achieve perfect secrecy, while the unpredictable wireless channel is shown to be a good random source. There is very few work of the joint design of OTP and key generation from wireless channels. This article provides a comprehensive and quantitative investigation on secure transmission achieved by OTP and wireless channel randomness. We propose two OTP secure transmission schemes, i.e., identical key-based physical-layer secure transmission (IK-PST) and un-IK-PST (UK-PST). We quantitatively analyze the performance of both schemes and prove that UK-PST outperforms IK-PST. We extend the pairwise schemes to a group of users in networks with star and chain topologies. We implement prototypes of both schemes and evaluate the proposed schemes through both simulations and experiments. The results verify that UK-PST has a higher effective secret transmission rate than that of IK-PST for scenarios with both pairwise and group users.
As an alternative and appealing approach to providing information security in wireless communication systems, secret key generation at physical layer has demonstrated its potential in terms of efficiency and reliability over traditional cryptographic methods. Without the necessity of a management centre for key distribution or reliance on computational complexity, physical layer key generation protocols enable two wireless entities to extract identical and dynamic keys from the randomness of the wireless channels associated with them.\nIn this thesis, the reliability of secret key generation at the physical layer is examined in practical wireless channels with imperfect channel state information (CSI). Theoretical analyses are provided to relate key match rate with channel's signal-to-noise ratio (SNR), degrees of channel reciprocity, and iterations of information reconciliation.\nIn order to increase key match rate of physical layer secret key generation, improved schemes in the steps of channel estimation and sample quantization are proposed respectively. In the channel estimation step, multiple observations of the wireless channels are integrated with a linear processor to provide a synthesized and more accurate estimation of the wireless channel. In the sample quantization step, a magnitude based quantization method with two thresholds is proposed to quantize partial samples, where specific quantization areas are selected to reduce cross-over errors. Significant improvements in key match rate are proven for both schemes in theoretical analysis and numerical simulations. Key match rate can even achieve 100% in both schemes with the assistance of information reconciliation process.\nIn the end, a practical application of physical layer secret key generation is presented, where dynamic keys extracted from the wireless channels are utilized for securing secret data transmission and providing efficient access control.
The intrinsic broadcast nature of wireless communication let the attackers to initiate several passive attacks such as eavesdropping. In this attack, the attackers do not disturb/stop or interrupt the communication channel, but it will silently steal the information between authentic users. For this purpose, physical layer security (PLS) is one of the promising methodologies to secure wireless transmissions from eavesdroppers. However, PLS is further divided into keyless security and secret key‐based security. The keyless security is not practically implemented because it requires full/part of instantaneous/statistical channel state information (CSI) of the eavesdroppers. Alternatively, key‐based security is exploiting the randomness and reciprocity of wireless channels that do not require any CSI from an eavesdropper. The secret key‐based security is due to the unpredictability of wireless channels between two users. However, the secret key‐based security mainly on two basic parameters, i.e. coherence time and transmission power. Nevertheless, the wireless channel between users has a short coherence time, and it will provide shorter keys' length due to which eavesdropper can easily extract keys between communicating parties. To overcome this limitation, we proposed the power allocation scheme to improve the secret key generation rate (SKGR) to strengthen the security between authentic users.