Unauthorized Receivers Research Articles

Key-aggregate based access control encryption for flexible cloud data sharing

Cloud computing has become the priority for users to store and share data due to its numerous tempting advantages. The “encryption-before-outsourcing” mechanism is necessary to protect data privacy against the semi-trusted cloud server. Key-Aggregate Cryptosystem (KAC) is a novel encryption paradigm for cloud data sharing. It enables users to decrypt multiple data encrypted with different keys using a constant size aggregate key. When selectively sharing data, the KAC effectively addresses the challenges of expensive key management in symmetric encryption (SE) and eliminates the need for multiple copies of ciphertexts in public key encryption (PKE). However, previous KAC schemes can only control what data users are allowed to receive by distributing aggregate keys, but not what data users can send. This limitation could potentially allow a malicious data owner to leak sensitive information by distributing aggregate keys to unauthorized users. Therefore, this paper aims to design the key-aggregate cryptosystem with bidirectional access control, which can control both what the user can receive and what the data owner can send. Inspired by access control encryption (ACE), we first propose a key-aggregate based access control encryption with user level (KA-ACE-UL) system that can control whether a sender can share his data with a receiver. Then, we investigate a finer-grained access control policy and propose a key-aggregate based access control encryption with user-data level (KA-ACE-UDL) system that can control the data classes a sender can share with a receiver. We instantiate the KA-ACE-UL and KA-ACE-UDL schemes based on Chu et al.’s KAC scheme. We prove our proposed schemes can achieve both secure data storage and controlled data sharing, ensuring security against unauthorized receivers and malicious senders. Finally, theoretical performance analysis and practical experiments show the efficiency of our proposed schemes.

Jamming-Enhanced Secure UAV Communications With Propulsion Energy and Curvature Radius Constraints

A multi-unmanned aerial vehicles (UAVs)-aided secure communication network is studied, where multiple information UAVs carrying temporary aerial base stations transmit confidential information to multiple authorized receivers (ARs), and a jammer UAV is employed to send artificial noise to multiple unauthorized receivers (URs) for mitigating information leakage. Some practical constrains including the inter-UAV interference among the information UAVs and the jammer UAV, the maximal available propulsion energy at UAVs, and the curvature radius limitations of UAVs' trajectories are concurrently taken into account. In order to maximize the minimum secrecy rate among the ARs, the AR scheduling, the UAVs' power allocation and the trajectories of UAVs are jointly optimized by formulating a multi-variable optimization problem. To solve the non-convex problem efficiently, we present a block coordinate descent (BCD)-based approach, where the penalty dual decomposition (PDD)-based algorithm is designed to optimize the AR scheduling, and successive convex approximation (SCA)-based algorithm is proposed to optimize the UAVs' power allocation and the trajectories of UAVs. The complexity of the presented BCD-based approach is analyzed, which achieves polynomial complexity. Simulation results show that imposing curvature radius limitations on the UAVs' trajectory design is effective to avoid sharp turning of UAVs. Moreover, as curvature radius increases, the system max-min secrecy rate decreases. Besides, the secrecy rate performance of the system can be enhanced by exploiting one jammer UAV to interfere with the URs.

Energy Efficiency in Secure VLC Networks With SLIPT

This letter focuses on maximizing the energy efficiency (EE) for secure visible light communication (VLC) network with simultaneous lightwave information and power transfer (SLIPT) by optimizing the beamforming vectors and direct current (DC) bias under the constraints of the minimal rate requirement, the secure transmission requirement, the minimal energy harvesting (EH) requirement, and total power budget at the transmitters. To solve the non-convex optimization problem, we present a dual-layer iterative algorithm based on Dinkelbach’s and successive convex approximation (SCA) methods. An efficient algorithm is also designed to find a good initial point to accelerate the convergence. Simulation results show three typical phenomena: (1) the EE first remains unchanged and then decreases with the increasing EH requirement; (2) compared with the traditional sum-rate maximization design, our proposed approach achieves notable EE performance gain under the secure constraints; (3) the number of the authorized receivers, as well as the number of the unauthorized receivers, imposes significant impact on the EE performance.

AN-aided beamforming for IRS-assisted SWIPT systems

This paper studies artificial noise (AN)-aided beamforming design in an intelligent reflecting surface (IRS)-assisted system empowered by simultaneous wireless information and power transfer (SWIPT) technique. Multiple power splitting (PS) single-antenna receivers simultaneously receive information and energy from a multi-antenna base station (BS). Although all users are legitimate, in each transmission interval only one receiver is authorized to receive information and the others are only allowed to harvest power which are considered as unauthorized receivers (URs). To prevent information decoding by URs, AN signal is transmitted from the BS. We adopt a non-linear model for energy harvesting. In the optimization problem, we minimize the total transmit power, and for this purpose, we utilize an alternating optimization (AO) algorithm. For the non-convex rank-one constraint for IRS phase shifts, we utilize a sequential rank-one constraint relaxation (SROCR) algorithm. In addition to single antenna URs scenario, we investigate multi-antenna URs scenario and evaluate their performance. Simulation results validate the effectiveness of using IRS.

Efficient Secure NOMA Schemes Based on Chaotic Physical Layer Security for Wireless Networks

Non-orthogonal multiple access (NOMA) is considered by the 3GPP as a potential technology for beyond 5G wireless networks to support massive connectivity with robust reliability. However, the massive increase in connected users critically leads to data security problems owing to the high possibility of eavesdropping. In this paper, uplink secure NOMA (sNOMA) schemes based on chaotic physical layer security (PLS) are proposed to achieve two-fold secrecy of integrated channel coding and secret key approaches. Different code-domain and power-domain techniques are employed for sNOMA designs over realistic fading channel environments. Equal power allocation strategy is used for the transmitted chaotic signals in code-domain sNOMA (CD-sNOMA), whereas dynamic power control is employed in power-domain sNOMA (PD-sNOMA) and the hybrid code-power-domain sNOMA (CPD-sNOMA) approaches. The former design adopts joint maximum Likelihood (ML) signal detection while the later scenarios utilize integrated receiver designs based on successive interference cancellation (SIC) and ML techniques. For the proposed sNOMA schemes, power control algorithms are presented to optimize the system performance over constrained total received power and target error rate. Numerical results validate the effectiveness of sNOMA designs compared with the benchmark systems under the worst-case secrecy of unauthorized receiver with complete knowledge of the transmission scheme and associated channel,. Valuable tradeoffs are demonstrated between the achieved error rate, connectivity, security gap, and complexity. Moreover, the utilized chaotic signals offer robust and cost-effective PLS solutions with a huge key-space to combat the most powerful brute-force eavesdropping attacks.

Information hiding in images using Discrete Cosine Transform

In this era of development and increasing use of the Internet, user facing security problem during information sharing in which unauthorized receivers can gain access to the information transmitted. Data hiding during the transmission of information via the internet is one of the techniques used to keep the secrecy of the information to the unauthorized/ unintended persons. Steganography is a way of hiding secrets information by inserting it into an audio, video, image or text file without raising any suspicious to unintended persons. This paper presents the study which hides text messages into the image file by using Discrete Cosine Transform (DCT) steganography method. The method of this work by transforming the cover image and text message from spatial domain to frequency domain and use redundant bit of cover image to hide text message in such a way that unintended person will continue to see it as a normal image. The method continues to keep the quality of the cover image which transfers the information to reduce suspicion. Steganography is most used in military, law enforcement agency, corporate spies and in the medical area for hiding sensitive information.

Secrecy in wireless communication through closed-loop receiver de-synchronization

A subset of the synchronization algorithms in a wireless receiver are responsible for tracking the phase and frequency of a digitally modulated signal. If variations of the phase in the signal are substantial, then the receiver might be unable to track them leading to inability to demodulate the data. In this paper we propose a method for improving the secrecy of wireless communication by ensuring that an arbitrary unauthorized receiver (URx) cannot track these phase and frequency changes but a legitimate (LRx) one can. This is accomplished by introducing artificial variations in the phase of a wireless transmitted signal that exceed the capabilities of a certain class of receivers. We explore receivers that employ closed-loop synchronization, namely a phase-lock loop (PLL) and we devise an artificial frequency variation pattern that can de-synchronize it. Our results indicate that with our method the bit error rate (BER) of an URx can be maintained at a pretty high level even for very favorable channel conditions.

Exploring a novel fusion-scheme based on mathematical equation system for encryption-image algorithm

Exploring the conception of robust encryption techniques for the security of digital images is a permanent necessity due to the existence of the Internet where sending and receiving information to establish communication is a high priority activity. Encryption process is carried out by data transformation, i.e. shuffled or scrambled, so that the information can not be read by an unauthorized receiver and it can exclusively be decrypted using valid-keys. In this paper, a novel fusion-scheme based on mathematical equation system for encryption-image algorithm is explored. In order to do that, numerical pixels are introduced in a system of equations for fusing images with three different private-keys. In addition, classical tests between original and encrypted images such as correlation coefficient, number of changing pixel rate (NPCR), unified average changed intensity (UACI) and entropy have been carried out to support the effectiveness of image fusion for image encryption.

Learning-based attacks for detecting the vulnerability of computer-generated hologram based optical encryption.

Optical encryption has attracted wide attention for its remarkable characteristics. Inspired by the development of double random phase encoding, many researchers have developed a number of optical encryption systems for practical applications. It has also been found that computer-generated hologram (CGH) is highly promising for optical encryption, and the CGH-based optical encryption possesses remarkable advantages of simplicity and high feasibility for practical implementations. An input image, i.e., plaintext, can be iteratively or non-iteratively encoded into one or several phase-only masks via phase retrieval algorithms. Without security keys, it is impossible for unauthorized receivers to correctly extract the input image from ciphertext. However, cryptoanalysis of CGH-based optical encryption systems has not been effectively carried out before, and it is also concerned whether CGH-based optical encryption is sufficiently secure for practical applications. In this paper, learning-based attack is proposed to demonstrate the vulnerability of CGH-based optical security system without the direct retrieval of optical encryption keys for the first time to our knowledge. Many pairs of the extracted CGH patterns and their corresponding input images (i.e., ciphertext-plaintext pairs) are used to train a designed learning model. After training, it is straightforward to directly retrieve unknown plaintexts from the given ciphertexts (i.e., phase-only masks) by using the trained learning model without subsidiary conditions. Moreover, the proposed learning-based attacks are also feasible and effective for the cryptoanalysis of CGH-based optical security systems with multiple cascaded phase-only masks. The proposed learning-based attacking method paves the way for the cryptoanalysis of CGH-based optical encryption.

A secured data hiding using affine transformation in video steganography

Abstract Network security is the most essential aspect of information technology among today’s emerging digital technologies which demands secured communication of information. In this digital network, it is essential to secure the data from intruders and unauthorized receivers. Steganography plays a vital role in secure transmission of data. This paper proposes a steganography method to hide data using affine transformation technique. The secret data are embedded in the coefficients of integer wavelet transform of the video frames. While embedding, the pixel values are distributed using affine transformation. The proposed method has been tested on many input data and the performance is evaluated both quantitatively and qualitatively. The results indicate the enhanced capability of the proposed method that can ensure imperceptible distortions with minimum computational cost in terms of PSNR factor over the existing methods.

Secrecy improvement via joint optimization of UAV relay flight path and transmit power

Eavesdropping occurs when an unauthorized receiver secretly intercepts a transmitted signal. In this paper, we investigate the optimum flight path and transmit power for an unmanned aerial vehicle (UAV) relay to improve secrecy performance in the presence of an eavesdropper. We propose an algorithm based on particle swarm optimization (PSO) where the UAV flight path and power are jointly optimized to maximize the secrecy capacity. Simulation results show that the proposed algorithm is capable of achieving a performance that is close to the ideal secrecy performance. Simulation results also highlight the benefits of power optimization.

Simple 2D chaotic remapping scheme for securing optical communication networks

In this work, a simple and new method is proposed to simultaneously improve the physical layer security and the transmission performance of the optical orthogonal frequency division multiplexing system, by combining orthogonal frequency division multiplexing technique with chaotic theory principles. In the system, a 2-D chaotic map is employed. The introduced system replaces complex operations such as matrix multiplication with simple operations such as multiplexing and inverting. The system performance in terms of bit error rate (BER) and peak to average ratio (PAPR) is enhanced. The system is simulated using Optisystem15 with a MATLAB2016 and for different constellations. The simulation results showed that the BER of an unauthorized receiver reaches 0.5. Furthermore, the peak-to-average-power-ratio (PAPR) of the transmitted OFDM signal can be decreased by about 0.8 dB at BER equal to 10^-4.

WFRFT Secure Communication Method Based on Chaotic Parameter Pool

In this study, to solve the hidden limitation of conventional weighted fractional Fourier transform (WFRFT), a random modulation order parameter pool is established by applying chaos technology. Further, a WFRFT secure communication method based on the chaotic parameter pool (CPP) is proposed. Based on the effective characteristics of tent mapping and the sequence output range, the parameter pool constructor is established by parameter transformation. Furthermore, for each parameter selection period, the information can be processed by WFRFT using different modulation orders. The modeling and simulation demonstrate that this method can significantly increase the bit error rate and processing time of unauthorized receivers. This indicates that it can greatly increase the scanning difficulty of unauthorized users and improve the concealment and security of the original information transmission.

A Physical-Layer Secure Coding Scheme for Indoor Visible Light Communication Based on Polar Codes

Visible light communication (VLC) can provide short-range optical wireless communication together with illumination using LED lightings. Since VLC channel is an open wireless channel, physical-layer security is desirable in order to hide secret information from unauthorized receivers, without reliance on upper-layer cryptographic techniques. In this paper, a secure coding scheme based on polar codes is proposed to simultaneously achieve physical-layer security and transmission reliability for indoor VLC systems under Wyner's wiretap model. An indoor VLC degraded wiretap channel model and an indoor VLC undegraded wiretap model are analyzed to estimate the corresponding secrecy capacity with typical indoor VLC scenarios considering the requirements of illumination and reliable transmission. Then, a physical-layer secure coding scheme and an enhanced scheme are designed to provide securely reliable communication without sacrificing the illumination functionality. Numerical results show that for VLC degraded wiretap channel, the proposed coding scheme can reduce the bit error rate (BER) of main channel to nearly 0 and increase that of wiretap channel to 0.5. Therefore, the mutual information between the sender and the eavesdropper and the BER of the legitimate receiver are both decreased to nearly 0. Both the security and reliability of VLC are guaranteed by the proposed coding scheme. And the practical secrecy rate reaches 85.96% at some positions when codeword length is 2 048 bits. Furthermore, an enhanced coding scheme with a feedback channel is proposed to handle the case that the wiretap channel is not degraded with respect to the main channel. With the feedback channel, the wiretap channel can be equivalently degraded and the security can be increased gradually with the increment of the degradation level of the wiretap channel. Meanwhile, the secrecy capacities can be asymptotically achieved for indoor VLC systems.

Secrecy performance of noncoplanar SIMOME NLOS ultraviolet communications over turbulence channels

Abstract This paper considers improving the confidentiality of non-line-of-sight (NLOS) ultraviolet (UV) links within the framework of physical-layer security. We study an NLOS UV scenario with one transmitter, one legitimate receiver and an eavesdropper. The transmitter has only one receive aperture, while the legitimate and unauthorized receivers have multiple receive apertures. Maximum ratio combining (MRC) and equal gain combining (EGC) techniques are utilized to overcome the data rate bottleneck and security risk induced by scattered UV channels and atmospheric turbulence. Alignment errors are exit in the noncoplanar single-input multiple-output multi-apertures eavesdroppers (SIMOME) NLOS UV communication system. The expressions of the average secrecy capacity (ASC), the secrecy outage probability (SOP) and the probability of positive secrecy capacity (PPSC) are derived. It is founded that the smaller the transmit or receive elevation angles are, the better the secrecy performance is. Spatial diversity techniques can improve the confidentiality of NLOS UV links with smaller off-axis errors.

An Electromagnetic Analysis of Noise-Based Intrinsically Secure Communication in Wireless Systems

Recently there has been an increasing interest toward unconditionally secure communication systems in which the mechanism assuring the secrecy of the message is physical and not computational. An interesting approach proposed in the information theory literature for unconditionally secure communication is based on the use of artificial noise at a rate related to the difference between the mutual information in perfect secrecy. Since the mechanism assuring the secrecy of the message is physical and not computational, the unauthorized receiver cannot obtain information from the received signal, regardless of how much computational power is available. For this reason, such a cryptographic system is called unconditionally secure. The aim of this paper is to investigate an electromagnetic approach to the noise-based wireless communication systems stressing the important role of the electromagnetic propagation and antenna design. In particular, the concept of the number of degrees of freedom of the field is used to clarify the physical mechanism that allows for a decrease in the mutual information of the unauthorized channel compared to the eavesdropper channel. Numerical examples regarding both free-space propagation and rich scattering environments are shown, confirming the importance of the role of the electromagnetic propagation and antenna design.

A Joint Optimization Scheme for Artificial Noise and Transmit Filter for Half and Full Duplex Wireless Cyber Physical Systems

While half and full duplex wireless enabled cyber physical systems (CPSs) are gaining more importance and research attention, maintaining the security of CPS systems remains a vital challenge. The broadcast nature of wireless channels makes it possible for unauthorized receivers, called eavesdroppers, to capture the information signal. Wireless physical layer security techniques aim to harden the secrecy characteristics of wireless systems, decreasing the signal quality of a prospective eavesdropper. This paper considers a joint optimization of artificial noise (AN) signal and transmit filter for the information signals in order to achieve a target secrecy level. As eavesdropping attacks are very critical threats in CPS networks, and the need for high secrecy techniques remains valid. The proposed framework includes a scenario with two multi-antenna legitimate parties and a multi-antenna eavesdropper node (or multiple cooperating eavesdroppers). The transmit filter and AN signal are jointly optimized by the transmitters, where receiver nodes can make use of optimal transmit filters. The problem is derived for the cases where the legitimate CPS nodes perform full duplex and half duplex transmissions. The impact of channel estimation errors and self interference are also discussed.

Comparison of Performance based on Power of Energy Encryption in Medium Field for Wireless Power Transfer System

<p class='IJASEITAbtract'>Encryption is a very important technique used to protect energy transmission channels from an unauthorized receiver. It can be utilized to transmit data securely over the wireless medium. Encryption techniques of wireless power transfer (WPT) are important in the research on the effects of security key for security of energy transfer to the authorized receiver. The energy encryption scheme of WPT is proposed to chaos theory. Chaos theory is applicable to the logistic map to propose as a security key to chaotically regulate the switching frequency. Furthermore, for chaos theory characteristic effect power and distance performance. Therefore, this paper investigates mainly effective power based on mobile charging application. This research is focusing on performance on power of energy encryption in medium field for wireless power transfer system. This research is dedicated to the comparison of performance in power based on mobile charging application. The optimization to transport the power in this research based on comparison of power is 10W. The research utilized MATLAB simulation to compare the performance.

An Attribute-Based Anonymous Broadcast Encryption Scheme with Adaptive Security in the Standard Model

In broadcast encryption schemes, a distribution center broadcasts an encrypted message to a subset chosen from a universe of receivers and only the intended users are able to decrypt the message. Most broadcast encryption schemes do not provide anonymity and the identities of target receivers are sent in plaintext. However, in several applications, the authorized users’ identities have the same sensitivity as the broadcasted messages. Yu, Ren and Lou (YRL) considered this issue and introduced an e€icient anonymous a‚ribute-based broadcast encryption scheme. In this paper, we first propose an a‚ack on the YRL scheme and showthat the unauthorized receivers can also decrypt the broadcasted message. Next, we propose the Improved-YRL scheme and prove that it achieves anonymity and semantic security under adaptive corruptions in the chosen ciphertext se‚ing. The proof is provided using the dual system encryption technique and is based on three complexity assumptions in composite order bilinear maps. The Improved-YRL scheme is a step forwardin solving the long-standing problem of secure and low overhead anonymous broadcast encryption.

On Artificial-Noise-Aided Transmit Design for Multiuser MISO Systems With Integrated Services

This paper considers artificial noise (AN)-aided transmit designs for multi-user MISO systems in the eyes of service integration. Specifically, we combine two sorts of services, and serve them simultaneously: one multicast message intended for all receivers and one confidential message intended for only one receiver. The confidential message is kept perfectly secure from all the unauthorized receivers. Our goal is to jointly design the optimal input covariances for the multicast message, confidential message and AN, such that the achievable secrecy rate region is maximized subject to the sum power constraint. This secrecy rate region maximization (SRRM) problem is a nonconvex vector maximization problem. To handle it, we reformulate the SRRM problem into a provably equivalent scalar optimization problem and propose a searching method to find all of its Pareto optimal points. The equivalent scalar optimization problem is identified as a secrecy rate maximization (SRM) problem with the quality of multicast service (QoMS) constraints. Further, we show that this equivalent QoMS-constrained SRM problem, albeit nonconvex, can be efficiently handled based on a two-stage optimization approach, including solving a sequence of semidefinite programs. Moreover, we also extend the SRRM problem to an imperfect channel state information (CSI) case where a worst-case robust formulation is considered. In particular, while transmit beamforming is generally a suboptimal technique to the SRRM problem, we prove that it is optimal for the confidential message transmission whether in the perfect CSI scenario or in the imperfect CSI scenario. Finally, numerical results demonstrate that the AN-aided transmit designs are effective in expanding the achievable secrecy rate regions.