Due to the enormous spreading of applied wireless networks, security is actually one of the most important issues for telecommunications. One of the main issue in the field of securing wireless information exchanging is the initial common knowledge between source and destination. A shared secret is normally mandatory in order to decide the encryption (algorithm or code or key) of the information stream. It is usual to exchange this common a priori knowledge by using a “secure” channel. A new modulation technique, able to encrypt the radio signal without any a priori common secret between the two nodes, was previously proposed by the authors [1]-[3]. The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. This contribution improves the previous works by exploring the real robustness of the proposed technique against the presence of DOS warriors and impairment of the radio channel, considering also implementation details, such as the bit integration time. Both the case of passive and active attacks have also been implemented and simulated by using the Matlab Simulink.
Due to the enormous spreading of applied wireless networks, security is actually one of the most important issues for telecommunications. One of the main issue in the field of securing wireless information exchanging is the initial common knowledge between source and destination. A shared secret is normally mandatory in order to decide the encryption (algorithm or code or key) of the information stream. It is usual to exchange this common a priori knowledge by using a “secure” channel. A new modulation technique, able to encrypt the radio signal without any a priori common secret between the two nodes, was previously proposed by the authors [1]-[3]. The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. This contribution improves the previous works by exploring the real robustness of the proposed technique against the presence of DOS warriors and impairment of the radio channel, considering also implementation details, such as the bit integration time. Both the case of passive and active attacks have also been implemented and simulated by using the Matlab Simulink.
Due to the enormous spreading of applied wireless networks, security is actually one of the most important issues for telecommunications. One of the main issue in the field of securing wireless information exchanging is the initial common knowledge between source and destination. A shared secret is normally mandatory in order to decide the encryption (algorithm or code or key) of the information stream. It is usual to exchange this common a priori knowledge by using a "secure" channel. Nowadays a secure wireless channel is not possible. In fact normally the common a priori knowledge is already established (but this is not secure) or by using a non-radio channel (that implies a waste of time and resource). This contribution deals with the proposal of a new modulation technique ensuring secure communication in a full wireless environment. The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. The probability of error/detection is analytically derived for the legal users and for the third unwanted listener. The proposed scheme has also been implemented in a Xilinx Virtex II FPGA. All the results show that the performance of the proposed scheme yields the advantage of intrinsic security, i.e., the mutual information cannot be physically demodulated (passive attack) or denied (active attack) by a third terminal, leading us to conclude that the proposed technique is really useful for private key distribution in every wireless network.
The issues of privacy and security in wireless communication networks have taken on an increasingly important role as these networks continue to be deployed worldwide. Traditionally, security is viewed as an independent feature addressed above the physical layer and all widely used cryptographic protocols are designed and implemented assuming that the physical layer simply provides an error-free link. However, with the emergence of ad-hoc and decentralized networks, higher-layer techniques, such as encryption, are becoming complex and hard to be implemented, in particular in handy devices. Recently attention was moved to study the fundamental ability of the physical layer to provide secure wireless communications. In this contribution, we analyze, from an information-theoretic perspective, the performance of the Noise-Loop (NL) modulation, a physical-layer security technique previously presented in [1]. The capacity as well as the secrecy capacity of the NL modulation are derived and compared to a generic Gaussian channel. The results show that the proposed NL technique is able to produce a full-secrecy rate radio communication link.
In this paper we consider the problem of secure communication between two nodes, over a fading wireless medium, in the presence of a passive eavesdropper. We propose a scheme that provides security based on transforming the basic signal constellation to a higher order signal constellation with the help of conventional encryption method and then using channel knowledge (i.e. amplitude and phase variation), which is location specific, to distort the constellation of encrypted data. This scheme not only makes the estimation of the constellation difficult but also the type of modulation that is used for the adversary. BER (bit error rate) is used as performance metric. We find that the adversary suffers from high BER as compared to its legitimate counterpart.
The wireless radio communications channel between two legitimate user terminals has long been considered as a renewable source of shared secrecy. As characterization of the channel, the time-varying channel impulse response (CIR) is commonly used for this purpose due to its reciprocity and inherent difficulty in being captured by an adversary. While each terminal generates a secret key at its side, based on its own channel measurements combined with an independent noise component, mismatches may occur in the extracted information or in the obtained bit sequences after a sampling and quantization process. To mitigate such bit mismatches, we propose a method that utilizes the properties of the Golay code to correct or detect the bit mismatches for CIR-based secret key agreement. In our approach, the reconciliation information in the transmission is deliberately designed to hide the original shared information (perfect or imperfect). The correctness of our bit mismatch mitigation algorithm is thoroughly analyzed for all possible scenarios. In addition, the effectiveness of our algorithm is validated through simulations using MATLAB for generated CIR data, the results of which match our theoretical analysis. Our design is shown to be secure and optimal by security analysis and comparisons between our proposed algorithm and its variants. The comparisons with related techniques and the scenarios in which our design can benefit are also discussed.
Security is one of the key requirements of wireless communication systems. By exploiting the broadcast nature of wireless medium, a malicious user might attempt to mislead the legitimate nodes, intercept the communication and overhear the private information. In order to combat against such malicious attacks, various encryption using security techniques have been proposed in the literature. Recently, physical layer (PHY) security has emerged as an additional countermeasure to the encryption based approaches and become very popular. Unlike cryptography, PHY security techniques target to protect the signal itself rather than encrypting the information bits. However, most of these techniques are designed based on specific channel conditions. Since channel has a random nature and cannot be controlled by users, such a design approach may remain unreliable for many practical scenarios where the desired channel state does not exist. Therefore, in this study, we highlight the importance of the channel independent PHY security techniques. In order to draft the ongoing efforts and provide the open issues in this direction, three different concepts are discussed along with the reviews of sample studies.
A new framework for secure communication in physical layer is proposed. A network of users equipped with coupled dynamical systems is considered. The aim is to securely exchange messages between network nodes in the presence of an eavesdropper, referred to as Eve. Unlike a traditional wireless system, the messages to be conveyed are not sent directly through the medium. Instead, they are mapped to initial conditions of the dynamical system. Once the system converges to a steady state, conditions of the local system at each node is measured to recover the sent messages. A fundamental property of the proposed system which makes it secure is that Eve is not part of the dynamical system and hence, she does not observe the initial conditions of the nodes for steady state comparison measurement. In particular, a situation with two users is considered. The proposed system is then modeled as a two-way wiretap channel and the secrecy capacity region is derived under various conditions. A consequence of our result is that regardless of Eve's physical location and how strong her receiver is the achievable rates are positive, i.e., secure communication is possible. Furthermore, a radio frequency (RF) system is proposed to realize this model in a wireless setting by means of local coupled oscillators. In particular, a unidirectional master-slave coupling architecture is considered where a power-constrained slave node synchronizes its frequency with a high-power master node. It is shown how the coupling mechanism, realized by transmitting and receiving power between the RF front-ends of the master and the slave node, can be used by the slave node to securely send messages or to share secret keys with the master node. To the best of our knowledge, this is the first architecture providing physical layer secret key generation fully designed in the RF front-end. The proposed RF system is simulated using Advanced Design System (ADS). The simulation results are shown for a 10m channel link and confirm the security condition. The secret key generation rate is 2 bits per synchronization time-frame which is dominated by the wave propagation delay between the two nodes.