Search

This paper analyzes the security issues of the recently proposed image encryption scheme based on paired interpermuting planes. The permutation process of the scheme is designed to permute the pixel values between colour channels and in the diffusion process, the function value of previous cipher is xored to the current pixel, where the function is a permutation map. For a single round encryption/decryption, the chosen plaintext/ciphertext attack is performed to find the permutation map and the keys of the permutation process. A modified scheme is proposed in which the permutation is done in two stages, within the colour channel using generalised cat map and between the colour channels that depends on the values of the pixel after the permutation within the colour channel. The diffusion process chooses the xoring value based on the previous pixel cipher value and the pixel location. These processes are designed to overcome the weaknesses identified and the to resist the chosen plaintext/ciphertext attack. [ABSTRACT FROM AUTHOR]

Here is a proposal of lossless dual-channel audio encryption scheme based on one-time keys, the novelty is to apply chaotic system with changeable multi-scroll to generate key stream to confuse and diffuse audio data, and the one-time keys, such as initial values of state variables, scroll number and initial iteration times of the chaotic system, are dependent on both external keys and hash value of the plain audio file, to make the chaotic trajectory more unpredictable. The algorithm owns large key space to make brute-force attack impossible. Statistical analysis demonstrates the effectiveness for fast audio encryption, and the scheme can also be applied in encrypting audio with more channels. [ABSTRACT FROM AUTHOR]

A comparative study of femtosecond pulse dynamics in a photonic crystal fiber amplifier with backward and forward pump schemes is demonstrated experimentally and numerically. The output power, pulse duration and spectrum width of the amplified soliton pulse at different pump powers under the two pump schemes are discussed. The results show that the evolution of the soliton pulse shape in the temporal and spectral domains is also dependent on the direction of pump besides the output power. A narrower pulse duration and spectral width (i.e. smaller time-bandwidth-product), the much less nonlinearity accumulation (i.e. smaller B-Integral value) and a higher output power can be obtained in the backward pump scheme compared to that in the forward pump scheme. The physical origin can be explained by the interaction among group-velocity dispersion, self-phase modulation and nonuniform gain distribution along the fiber due to different end-pump directions. The results provide convincing support to choose the backward pump scheme rather than the forward pump scheme in soliton amplification region in a femtosecond fiber amplifier. [ABSTRACT FROM AUTHOR]

In this paper, we proposes high payload reversible data hiding scheme using weighted matrix. Generate cover image by enlarge the size of original image using interpolation. Partition the original image into (3 × 3) pixel blocks and cover image into (5 × 5) blocks. Perform modular sum of entry-wise multiplication of an (3 × 3) original pixel block with same size shared predefined weighted matrix W . At most twelve multiplication operations are performed to embed 48 bits secret data within an (5 × 5) overlapped pixel block. In each operation, the data embedding position are identified and stored the positional value by modifying three least significant bits of the interleaved pixel of cover image to hide large amount of secret data. For i -th block i = 1, 2, …, we update the weighted matrix W i +1 as W i +1 = ( W i × κ − 1) mod 9, where gcd ( κ , 9) = 1. The original pixels are not effected during data embedding in our scheme which assure reversibility. The proposed scheme provides average embedding payload 2.97 bits per pixel (bpp) with good visual quality measured by peak signal to noise ratio (PSNR) guaranteed to be higher than 37.97 dB. Finally, we compare our scheme with other state-of-the-art methods and obtain reasonably better performance in terms of data embedding capacity. [ABSTRACT FROM AUTHOR]

Discovering dynamical systems with hidden attractors has become an attractive topic recently. A novel four-dimensional continuous-time autonomous system with a cubic nonlinear term is introduced in this work. It is worth noting that this no-equilibrium system can generate hidden hyperchaotic attractors. The fundamental properties of such systems are investigated by means of equilibrium points, phase portrait, bifurcation diagram and Lyapunov exponents. In addition, an adaptive scheme has been presented to synchronize two such identical hyperchaotic systems. Moreover, an electronic circuit is also designed and implemented to verify the feasibility of the theoretical model. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach based on minimum enclosing ball support vector machine (BVM) to phishing Website detection is proposed, which aims at achieving high speed and high accuracy for detecting phishing Website. In order to enhance the integrity of the feature vectors, we first perform an analysis of the topology structure of website according to the DOM tree and use the Web crawler to extract 12 topological features of the website. Then, the feature vectors are detected by BVM classifier. Compared with the general SVM, this method has relatively high precision of detecting, and complements the disadvantage of slow speed of convergence on large-scale data. The experimental results show that the proposed method has better performance than SVM, and further validate the validity and correctness of our scheme. [ABSTRACT FROM AUTHOR]

This paper analyzes the security issues of the recently proposed JPEG image encryption scheme. A new image encryption algorithm using modified logistic map is proposed. The chaotic sequences generated using modified logistic map are used for permutation, bit swapping and random diffusion. These processes impose the confusion and diffusion effect on the image and make the scheme secure. The security parameters such as entropy, correlation, NPCR and UACI are tested and the results show the scheme is secure. [ABSTRACT FROM AUTHOR]

The transthoracic echocardiographic (TTE) images used to assess cardiac health are inherent with speckle noise, making it very difficult for accurate abnormality diagnosis. To address this issue, a novel speckle reduction known as extreme total variation bilateral (ETVB) filter is proposed in this paper. The regularizer term of total variation (TV) method is replaced with the bilateral (BL) term in the proposed ETVB filter along with the prior term. The true information is incorporated in the algorithm using Bayesian inference and probability density function. Applications of gradient projection based restoration methods are also analyzed for speckle noise reduction. Denoising characteristics are evaluated in terms of 15 image quality metrics along with visual quality. The performance of proposed ETVB filter is compared with 30 existing despeckling techniques. Exhaustive result analysis reveals that the proposed ETVB filter is superior in terms of edge and texture preservation. The focal points of result analysis are edge, structure and texture preservation along with visual outlook. Edge and structure preservation are measured using beta metric, figure of merit and structure similarity index. The values of β , FoM and SSIM are markedly enhanced using proposed filtering scheme in comparison to other total variation based methods. [ABSTRACT FROM AUTHOR]

Reversible watermarking is mostly fragile, it can restore the original image losslessly if there is no attack during transmission. However, in real life, it is impossible not to be attacked completely. Reversible watermarking loses reversibility and becomes meaningless if it is attacked maliciously. In order to overcome this drawback and broaden its application field, an adaptive multifunctional watermarking scheme is proposed which is a special reversible watermarking scheme, which can not only restore the original image losslessly when it meets no attacks, but also can approximately recover the original image when it encounters malicious attacks. In the paper, the original image is divided into non-overlapping 8 × 8 blocks. And then, each block is transformed by IDCT (Integer Discrete Cosine Transform). The recovery watermark is generated by the method of 2DPCA (2 Dimension Principal Component Analysis) and the authentication watermark is produced by the special algorithm. According to the proposed block mapping method, the watermarks are embedded into its far mapping block adaptively. Moreover, MC (mapping and compensation) method is proposed to avoid overflow and underflow problems. The experimental results show that the proposed scheme can achieve reversibility and recoverability while keeping the lower distortion and higher embedding capacity. [ABSTRACT FROM AUTHOR]

Most of the existing color image watermarking schemes was designed to mark grayscale images or use the color components, which ignore the significant correlation between different color channels. Recently, several approaches were developed to process the color channels intrinsically, but they always cannot counterattack geometric distortions. It is a challenging work to design a robust color image watermarking scheme against geometrical distortions. In this paper, we propose a geometric correction based robust color image watermarking approach using quaternion Exponent moments (QEMs). The novelty of our approach is that (1) the QEMs are derived to deal with the color images in a holistic manner, and (2) the QEMs are exploited for estimating the geometric distortions parameters in order to permit watermark extraction. Experimental results confirm the validity of our approach and its higher robustness against geometrical distortions compared to alternative watermarking methods in the literature. [ABSTRACT FROM AUTHOR]

In this paper, we utilize optical hard-limiters to further enhance the system performance in balanced detection T/W optical CDMA system. In T/W optical CDMA systems, it had been investigated that the balanced detection scheme is not superior to the OOK scheme because of the adverse impact of beat noise. The employment of optical hard-limiter is an effective way to alleviate the deteriorating effect of beat noise. The carrier-hopping prime code is utilized as signature sequences whose out of phase autocorrelation is zero and the cross-correlation is at most one. Due to the orthogonality of signature sequence, the correlator of shifted version of carrier-hopping prime code is utilized in the receiver. The numerical results reveal that our proposed scheme can greatly reduce the error floor; also it is superior to that using OOK scheme with optical hard-limiter. Most important of all, our proposed scheme has fixed and optimum thresholds which do not vary with system parameters; and this will lead to dynamic estimation of optimal thresholds unnecessary in the receiver. [ABSTRACT FROM AUTHOR]

Abstract: Since the color image watermark has more bit information, it is a challenging problem to design a robust and blind color watermarking scheme for copyright protection. In this paper, a blind watermarking scheme based on singular value decomposition (SVD) is proposed. By analyzing the orthogonal matrix U via SVD, it is found that there exists a strong similarity correlation between the second row first column element and the third row first column element. Hence, this paper utilizes this property for image watermarking. Firstly, the 4×4 non-overlapping pixels block of each component in color host image is processed by SVD. And then, the color watermark is embedded by slightly modifying the value of the second row first column element and the third row first column one of U matrix, and the modified relation can be utilized to extract watermark. Experimental results, compared with the related existing methods, show that the proposed color image scheme has stronger robustness against most common attacks such as image compression, filtering, cropping, noise adding, blurring, scaling and sharpening et al. [Copyright &y& Elsevier]

Abstract: Delay preemption that combines the techniques of preemption and small buffers is an efficient solution for burst contention. However, due to the phenomenon of over-usage on buffer, the low-loss demand of high priority is not ensured especially in high traffic states. In this article, to improve the blocking of delay preemption, we propose a modified scheme named limited delay preemption based priority (limited-DPP) that constrains the buffered right of low priority within the moderate and high traffic states. To validate the efficiency of limited-DPP, the comprehensive analysis and simulation are performed in terms of loss and buffering time. [Copyright &y& Elsevier]

Abstract: Using the original and ‘symmetrical face’ training samples to perform representation based face recognition was first proposed in [1]. It simultaneously used the original and ‘symmetrical face’ training samples to perform a two-step classification and achieved an outstanding classification result. However, in [1] the “symmetrical face” is devised only for one method. In this paper, we do some improvements on the basis of [1] and combine this “symmetrical faces” transformation with several representation based methods. We exploit all original training samples, left “symmetrical face” training samples and right “symmetrical face” training samples for classification and use the score fusion for ultimate face recognition. The symmetry of the face is first used to generate new samples, which is different from original face image but can really reflect some possible appearance of the face. It effectively overcomes the problem of non-sufficient training samples. The experimental results show that the proposed scheme can be used to improve a number of traditional representation based methods including those that are not presented in the paper. [Copyright &y& Elsevier]

Abstract: This paper proposes a dynamic routing, modulation level and spectrum allocation (RMLSA) scheme in the flexible optical wavelength-division multiplexing (FWDM) networks with modulation format conversion ability. The scheme considers the modulation format conversion at the intermediate nodes and addresses the fragmentation problem by avoiding appearance of them. The influence of routing to the emergence of the fragmentation is quantified, which is referenced to decide which one route of k-paths to use. Simulation results demonstrate efficient reductions in blocking rates and improvements in failure recovery rates for the scheme in the network. [Copyright &y& Elsevier]

Abstract: In recent years, a number of chaos-based image cryptosystems have been proposed to meet the increasing demand for real-time secure image transmission. In this paper, an improved diffusion scheme named continuous diffusion strategy is proposed to promote the efficiency of the conventional permutation–diffusion type image cipher. The new scheme contains a supplementary diffusion procedure after the conventional diffusion process and the control parameters are altered by the cipher image after the first diffusion procedure. As a result, the difference can be introduced at the beginning and spread out to the whole image, and hence the same level of security can be achieved with fewer overall rounds. Moreover, to further enhance the confusion effect of the diffusion operation, an intensive diffusion approach is proposed, using stretched key stream elements to perform a cyclic shift to the cipher pixels. Extensive cryptanalysis has been performed using differential analysis, key space analysis, key sensitivity analysis and various statistical analyses. Experiment results demonstrate that the new scheme has a high level of security and fast encryption speed for practical image encryption. [Copyright &y& Elsevier]

Abstract: In this paper, we investigate four-wave mixing (FWM) effects in the ultra-dense wavelength division multiplexing passive optical network (UDWDM-PON) system and propose an efficient channel allocation scheme to mitigate the FWM impact. This scheme is formed by grouping signal channels into several blocks with different channel spacing. Through numerical analysis and simulations, our proposed scheme is verified to be able to reduce the FWM effects and have higher bandwidth efficiency than the traditional unequal channel allocation scheme. The simulation results also demonstrate that our proposed scheme can achieve nearly 4dB increases in optical power budget of the UDWDM-PON systems at the BER of 1e−3, in comparison with the equal spaced channel scheme. [Copyright &y& Elsevier]

Abstract: In this paper, we propose a novel high-speed stream cipher encryption scheme based on the true random key generated by a chaotic semiconductor laser. A 5-Gbits/s non-return-to-zero plaintext is successfully encrypted and decrypted using this cryptography by numerical simulations. Compared with chaos-based optical communications for a single channel utilizing analog chaotic optical carrier, the performance of the proposed setup of stream ciphers based on true random numbers generated by chaotic light is improved. The scheme overcomes the shortcoming of quality decrease of chaos communications caused by decline of chaos synchronization. The proposed setup can be applied in the areas of real-time high-speed physical encryption. [Copyright &y& Elsevier]

Abstract: We propose a novel simultaneous multi-user en/decoder using super-structure fiber Bragg gratings (SFBGs) for multi-channel optical code-division multiple-access (OCDMA) applications. Each channel can generate and recognize codes for users individually. Therefore, the SFBG can make full use of the wavelength resource to enlarge the system capacity. In this paper, a 2-channel, 4-channel and 8-channel en/decoders are designed in a single SFBG with optimized performance for their auto-correlation peak over the maximum wing level ratios and peak over the maximum cross-correlation level ratios being larger than 17 and 10.2dB, respectively. [Copyright &y& Elsevier]

Abstract: In this paper, contention resolution scheme based on burst segmentation and deflection routing in the core node and composite burst assembly scheme at the edge node are proposed. In the core node, contention is resolved through incorporating prioritized burst segmentation with deflection routing scheme. The burst segmentation scheme allows the tail of original bursts or the head of contending bursts to be segmented. The segmented burst is scheduled on the optimum deflection path by deflection routing scheme. At the edge of the network, a composite burst assembly scheme combines packets of different classes into the same burst, placing the highest priority packets in the middle and low priority packets at the tail and the head of the burst. The priority lowers gradually from the middle of the burst to the ends. An analytical model is proposed to evaluate the contention resolution scheme through calculating packet loss probability and the normalized end-to-end delay. Results show that high-priority bursts have significantly lower packet loss probability and delay than low-priority. So the contention resolution scheme which incorporates burst segmentation with deflection routing tends to perform better than the scheme only with burst segmentation or deflection routing. [Copyright &y& Elsevier]

Abstract: A clock-recovery scheme is proposed for the burst-mode optical data transmission using 4-level pulse-amplitude modulation in passive optical networks. It utilizes the nonlinear relaxation oscillation from a directly modulated laser to generate a clock tone at the transmitter. At the receiver side, it employs an injection locked oscillator (ILO) to lock to the clock tone and generates a full clock. A band-pass-filter is inserted before the ILO to reduce the jitter in the generated clock. [Copyright &y& Elsevier]

Abstract: Unlike traditional video steganography, motion-vectors-based steganographic approaches embed messages by modifying the motion vectors of the cover video. The scheme may produce little quality degradation of the stego video and little influence on the statistical characteristics of the spatial or frequency coefficients of the frames. As a result, the existing video steganalytic algorithms based on the statistical features of frames or the correlation between adjacent frames cannot effectively detect the motion-vectors-based steganographic system. In this paper, an improved steganalytic method against motion-vectors-based steganography is proposed. Based on the proposed algorithm, the correlations between motion vectors both in spatial and temporal domain are effectively quantified and a novel 12 dimensional statistical feature vector is extracted. The support vector machine (SVM) is trained with these vectors to detect the presence of the hidden data. Compared with other algorithms, the proposed scheme has higher detection accuracy for the typical motion-vectors-based steganographic algorithms. [Copyright &y& Elsevier]

Abstract: We propose a heuristic priority based wavelength assignment (HPWA) scheme to minimize the blocking probability. In this scheme, the connection requests having same s–d pair are groomed first and then these groomed connection requests are served for routing and wavelength assignment according to their priority order. The priority order of each groomed connection request is estimated based on both the types of path (direct link physical path or in-direct link physical path) first and then their traffic volume. The performance analysis of our proposed scheme is made in terms of blocking probability and compared the same with similar heuristic non-priority based wavelength assignment (HNPWA) scheme. Simulation study shows that the blocking probability of HPWA scheme is less than that of NPRWA. It is also seen that the performance of the proposed scheme is better in comparison to HNPWA, when the number of connection requests increases in the network. [Copyright &y& Elsevier]

Abstract: A novel measurement scheme for a three dimensional (3D) curved surface area is proposed. This scheme consists of three steps. First, a light-pen single-camera 3D coordinate vision measurement system is devised to obtain the 3D coordinates of a detected curved surface. Second, an improved 3D deformable surface model is applied to converge to the curved surface accurately. Finally, for the convergent deformable surface, the surface area is computed using an integration scheme based on a two-triangle area computation. An experiment on a small curved surface area measurement indicates that this scheme''s measurement repetition error decreases to 0.5%, when the parametric step lengths of the deformable surface are 0.1. [Copyright &y& Elsevier]

Abstract: We present a method for data encoding in terms of spectral shifts in the source spectra. The spectral switching of polychromatic light due to temporal correlation, around the intensity minima in a Michelson Interferometer (MI) has been utilized for this purpose. The potential application of the encoding method for free space communication is described in detail. The advantages of this method are compared with the proposed schemes of data communication using spectral switches. The experimental constraints of this method are also discussed. [Copyright &y& Elsevier]

Unequal spaced channel allocation (USCA) is a technique to reduce Four wave mixing (FWM). In this paper, system performance of 8 channel WDM system considering different optical transmitter formats (RZ, NRZ, Raised cosine and Gaussian) using USCA has been evaluated in terms of Q-factor. The simulation results reveal that four wave mixing is minimum for NRZ format. Also the effect of changing the laser power and increasing the bit rate has been observed. [ABSTRACT FROM AUTHOR]

The paper proposes a novel two stage L-band erbium doped fiber amplifier with forward–backward pumping scheme for transmission of 32 wavelength division multiplexed (WDM) channels. It is gain clamped with an in-line fiber Bragg grating (FBG) to provide flat gain over 45nm by restricting and reutilizing amplified spontaneous emission (ASE). We demonstrate that it provides an efficient small signal gain with minimum noise figure of over 20dB and 5.5dB, respectively, in the L-band region (1565–1610nm) by comparing with its forward and backward pumped counterparts with fixed Er3+ fiber length of 20m for −30dBm/channel input power. We also obtain the gain and noise figure dependence as a function of each of the Er3+ fiber lengths, pump power (both 1480 and 980nm), and temperature. Hence a 10nm region (1580–1590nm) has been acknowledged where temperature variations become constricted for 30°C variations (15–45°C). [ABSTRACT FROM AUTHOR]