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Recent advancements in high resolution scalable video coding have significantly increased the computational complexities of watermarking solutions for real-time video encoding systems. This paper proposes a human visual system based watermarking algorithm for spatial scalable coding based on the H.264/SVC standard. The proposed algorithm extracts textural feature from a set of 7 high energy quantized coefficients in 4×4 luma INTRA-predicted blocks of all slices and embeds watermark into the highly textured block which has at least one non-zero coefficient in 6 selected locations. The same embedding process is performed for all layers of the video to improve robustness against common video processing attacks. Experiments were conducted by embedding up to 8192 watermark bits into a four-layer spatial scalable coded video. Results suggest that the proposed scheme produces watermarked video with an average visual quality degradation of ∼0.36 dB at the expense of 2.18% bitrate overhead. In addition, the proposed watermarking scheme achieves an average detection rate of 0.98, 0.97 and 0.71 against re-encoding, recompression and Gaussian filtering attacks, respectively, using the base layer, and above 0.97, 0.94 and 0.66, respectively when using any of the enhancement layer. [ABSTRACT FROM AUTHOR]

This paper proposes a three bit-serial and digit-serial semi-systolic GF (2 m ) multipliers using Progressive Product Reduction (PPR) technique. These architectures are obtained by converting the GF (2 m ) multiplication algorithm into an iterative algorithm using systematic techniques for scheduling the computational tasks and mapping them to Processing Elements (PE). Three different semi systolic arrays were obtained. ASIC implementation of the proposed designs and previously published schemes were used to verify the performance of the proposed designs. One proposed design has at least 29% lower area compared to previously published bit/digit serial multipliers. This design has also at least 70% lower power compared to previously published bit/digit serial multipliers. Another proposed design has at least 12% lower power-delay product (PDP) compared to previously published bit/digit serial multipliers. This makes the proposed designs more suited to resource-constrained embedded applications. [ABSTRACT FROM AUTHOR]

Like all software systems, databases are subject to evolution as time passes. The impact of this evolution can be vast as a change to the schema of a database can affect the syntactic correctness and the semantic validity of all the surrounding applications. In this paper, we have performed a thorough, large-scale study on the evolution of databases that are part of larger open source projects, publicly available through open source repositories. Lehman׳s laws of software evolution, a well-established set of observations on how the typical software systems evolve (matured during the last forty years), has served as our guide towards providing insights on the mechanisms that govern schema evolution. Much like software systems, we found that schemata expand over time, under a stabilization mechanism that constraints uncontrolled expansion with perfective maintenance. At the same time, unlike typical software systems, the growth is typically low, with long periods of calmness interrupted by bursts of maintenance and a surprising lack of complexity increase. [ABSTRACT FROM AUTHOR]

Although parallelization of computationally intensive algorithms has become a standard with the scientific community, the possibility of in-core vectorization is often overlooked. With the development of modern HPC architectures, however, neglecting such programming techniques may lead to inefficient code hardly utilizing the theoretical performance of nowadays CPUs. The presented paper reports on explicit vectorization for quadratures stemming from the Galerkin formulation of boundary integral equations in 3D. To deal with the singular integral kernels, two common approaches including the semi-analytic and fully numerical schemes are used. We exploit modern SIMD (Single Instruction Multiple Data) instruction sets to speed up the assembly of system matrices based on both of these regularization techniques. The efficiency of the code is further increased by standard shared-memory parallelization techniques and is demonstrated on a set of numerical experiments. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel ICA based MIMO-OFDM VLC scheme, where ICA is applied to convert the MIMO-OFDM channel into several SISO-OFDM channels to reduce computational complexity in channel estimation, without any spectral overhead. Besides, the FM is first investigated to further modulate the OFDM symbols to eliminate the correlation of the signals, so as to improve the separation performance of the ICA algorithm. In the 4×4MIMO-OFDM VLC simulation experiment, LOS path and NLOS paths are both considered, each transmitting signal at 100 Mb/s. Simulation results show that the BER of the proposed scheme reaches the 10 −5 level at SNR=20 dB, which is a large improvement compared to the traditional schemes. [ABSTRACT FROM AUTHOR]

A distributed multiple-input multiple-output (D-MIMO) system is a promising candidate for future wireless communications with significantly enhanced spectral and energy efficiency. For high data rate systems equipped with a large number of antennas, which cause a spatial antenna correlation, there is a strong motivation to develop schemes for achieving high energy efficiency and low computational complexity, while supporting high capacity. This paper proposes an effective near-optimal antenna selection algorithm with low complexity for correlated D-MIMO systems. The proposed algorithm begins with an antenna with the highest channel gain and adds the best antennas supporting the highest level of uncorrelation with the maximum channel gain in each step. Compared to the conventional algorithms via computer simulations, the proposed scheme achieved similar capacity to the optimal selection algorithms but with reduced hardware cost and complexity in several D-MIMO configurations with even highly correlated antennas. In particular, the performance gain of this scheme became significant when a small number of the best antennas were selected, resulting in high energy efficiency in D-MIMO systems. [ABSTRACT FROM AUTHOR]

Abstract: We propose a novel scheme for combining two adaptation terms of affine projection algorithms with different projection orders and step-sizes. The selection of the mixing parameter that determines the performance of the proposed combination scheme is derived by the largest decrease of the mean-square deviation. The experimental results show that the proposed algorithm exhibits a fast convergence speed and a small steady-state misalignment. Moreover, the proposed algorithm achieves a low computational complexity in the steady-state. [Copyright &y& Elsevier]

Abstract: Proxy Re-Encryption (PRE) allows one user to delegate the decryption rights of his/her ciphertexts to another user. Since the introduction of Multi-Hop Identity-Based PRE (MH-IBPRE) by Green and Ateniese, the ciphertext size and the decryption complexity grow linearly in the number of re-encryption “hops”. In this paper, for the first time, we propose an MH-IBPRE that maintains the (constant) ciphertext size and computational complexity regardless of the number of re-encryption hops. Moreover, our scheme is bidirectional and also supports conditional re-encryption. The scheme is proven secure against selective identity and chosen-ciphertext attacks and collusion resistant in the standard model. As of independent interest, we also show that the conditional re-encryption can also be extended to a set of conditions. [Copyright &y& Elsevier]

Abstract: Extended command governors (ECGs) are add-on schemes that modify set-point commands as necessary to ensure that imposed state and control constraints are not violated by closed-loop systems designed for set-point tracking. In this paper, we propose a reduced order ECG for systems with dynamics decomposable into slow and fast state variables. We demonstrate that ECG implementation can be based on slow states only, thus reducing the computational complexity. This is achieved by introducing additional constraints, and by slightly tightening the original constraints. We demonstrate that the proposed ECG maintains the response properties of the conventional ECG, including the convergence to the nearest feasible command in finite time in the case of constant reference commands. The results are also shown to apply to conventional command governors. For the case when the reduced order state is not directly measured, a formulation of the result in the presence of a state observer is developed. [Copyright &y& Elsevier]

Abstract: In verifiable multi-secret sharing schemes (VMSSs), many secrets can be shared but only one share is kept by each user and this share is verifiable by others. In this paper, we propose two secure, efficient, and verifiable multi-secret sharing schemes, namely Scheme-I and Scheme-II. Scheme-I is based on the Lagrange interpolating polynomial and the LFSR-based public key cryptosystem. The Lagrange interpolating polynomial is used to split and reconstruct the secrets and the LFSR-based public key cryptosystem is employed to verify the validity of the data. Scheme-II is designed according to the LFSR sequence and the LFSR-based public key cryptosystem. We compare our schemes with the state-of-the-art in terms of attack resistance, computation complexity, and so on, and conclude that our schemes have better performance and incur less computation overhead. Our schemes can effectively detect a variety of forgery or cheating actions to ensure that the recovery of the secrets is secure and creditable, and the length of the private key is only one third of that of others for the same security level. [Copyright &y& Elsevier]

Abstract: Stored-value cards (SVCs) are a kind of smartcards that can be used to store monetary values. SVCs have demonstrated a wide range of applications in commerce. SVCs are in general tamper-resistant, but they are very computationally weak and their security mechanisms are also weak against side-channel attacks. In this paper, we propose an efficient and secure stored-value card system. With the help of pre-computations, stored-value cards in our scheme are only required to perform simple arithmetic operations and bitwise comparisons. Our system especially for SVCs is secure with unbounded computational leakage resilience. Our novel scheme provides a practical solution to side-channel attacks for light-weight devices. [Copyright &y& Elsevier]

Abstract: In 2009, Wang et al. presented a dynamic ID-based remote user authentication scheme and claimed that their scheme was more efficient and secure. In this paper, we point out that their scheme is not secure against impersonation attacks launched by any adversary at anytime and could leak some key information to legal users, who can launch an off-line guessing attack. If the adversary could get the secret information stored in the smart cards someway, their scheme will be completely broken down. In addition, their scheme does not provide anonymity for the users, and lacks the functionalities of revocation, key exchange and secret renew for users and servers. Furthermore, we propose a more secure and robust scheme, which does not only cover all the above security flaws and weaknesses, but also provides more functionalities. [Copyright &y& Elsevier]

Abstract: It is a challenging work to design a robust halftone image watermarking scheme against desynchronization attacks. In this paper, we propose a feature-based digital watermarking method for halftone images with low computational complexity, good visual quality and reasonable resistance toward desynchronization attacks. Firstly, the feature points are extracted from host halftone image by using multi-scale Harris–Laplace detector, and the local feature regions (LFRs) are constructed according to the feature scale theory. Secondly, discrete Fourier transform (DFT) is performed on the LFRs, and the embedding positions (DFT coefficients) are selected adaptively according to the magnitude spectrum information. Finally, the digital watermark is embedded into the LFRs by quantizing the magnitudes of the selected DFT coefficients. By binding the watermark with the geometrically invariant halftone image features, the watermark detection can be done without synchronization error. Simulation results show that the proposed scheme is invisible and robust against common signals processing such as median filtering, sharpening, noise adding, and JPEG compression, etc., and desynchronization attacks such as rotation, scaling, translation (RST), cropping, local random bend, and print-scan, etc. [ABSTRACT FROM AUTHOR]

Abstract: According to actual needs, a generalized signcryption scheme can flexibly work as an encryption scheme, a signature scheme or a signcryption scheme. In this paper, firstly, we give a security model for identity based generalized signcryption which is more complete than the existing model. Secondly, we propose an identity based generalized signcryption scheme. Thirdly, we give the security proof of the new scheme in this complete model. Compared with existing identity based generalized signcryption, the new scheme has less implementation complexity. Moreover, the new scheme has comparable computation complexity with the existing normal signcryption schemes. [ABSTRACT FROM AUTHOR]