Parallel Performance of DES in ECB Mode
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This study presents the design and implementation of DES encryption in ECB (electronic codebook) mode under three different parallelization schemes. The first method we suggest is block based, where 64-bit blocks of text are distributed among the parallel processors. The second approach is pipeline based, where we parallelize each of the 16 internal rounds of DES. The third parallelization scheme is plaintext based which divides the plaintext into equal partitions first and then assigns the 64-bit blocks of each partition to parallel processors. We obtained runtime performances for each parallelization. To observe whether the source language has an effect on the overall performance, we run our algorithm on text from 5 different languages as English, French, German, Spanish and TurkishKeywords:
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This paper proposes a novel codebook for multiuser multiple-input multiple-output systems under spatially correlated channels. Existing codebooks designed for correlated channels either require accurate channel statistics which is not favorable for practical systems, or only perform well in highly correlated channels. In this paper, we first analyze the per-user rate loss led by using DFT codebook, then propose a two-level codebook, named weighted DFT codebook. It consists of a DFT-based codebook and a Grassmannian linear packing codebook. The proposed scheme does not need accurate channel statistics and can adapt to both correlated and uncorrelated scenarios. Simulation results show significant performance gain of the proposed codebook over the existing codebooks in various correlated channels.
Linde–Buzo–Gray algorithm
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The need for data encryption that protects sensitive data in a database has increased rapidly. However, encrypted data can no longer be efficiently queried because nearly all of the data should be decrypted. Several order-preserving encryption schemes that enable indexes to be built over encrypted data have been suggested to solve this problem. They allow any comparison operation to be directly applied to encrypted data. However, one of the main disadvantages of these schemes is that they expose sensitive data to inference attacks with order information, especially when the data are used together with unencrypted columns in the database. In this study, a new order-preserving encryption scheme that provides secure queries by hiding the order is introduced. Moreover, it provides efficient queries because any user who has the encryption key knows the order. The proposed scheme is designed to be efficient and secure in such an environment. Thus, it is possible to encrypt only sensitive data while leaving other data unencrypted. The encryption is not only robust against order exposure, but also shows high performance for any query over encrypted data. In addition, the proposed scheme provides strong updates without assumptions of the distribution of plaintext. This allows it to be integrated easily with the existing database system.
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This paper discusses the algorithms of codebook generation in SCHMM based speech recognition system and their fundamental principle. Introducing the basic discipline of Stochastic Relaxation- Division (SR-D) algorithm, it introduces the general idea into the authors' initial codebook generation algorithm. The experiment results show that the new method significantly improves the system performance. With the modified initial codebook, the model is further trained with the criterion of Maximum Likelihood(ML),which leads the codebook and other parameters more consistent and compatible.The effect of codebook size to final performance is also discussed and relative experiment results are presented.
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In the past more than one decade, hundreds of reversible data hiding (RDH) algorithms have been reported. Via exploring the correlation between the neighboring pixels (or coefficients), extra information can be embedded into the host image reversibly. However, these RDH algorithms cannot be accomplished in encrypted domain directly, since the correlation between the neighboring pixels will disappear after encryption. In order to accomplish RDH in encrypted domain, specific RDH schemes have been designed according to the encryption algorithm utilized. In this paper, we propose a new simple yet effective framework for RDH in encrypted domain. In the proposed framework, the pixels in a plain image are first divided into sub-blocks with the size of $m\times n$ . Then, with an encryption key, a key stream (a stream of random or pseudorandom bits/bytes that are combined with a plaintext message to produce the encrypted message) is generated, and the pixels in the same sub-block are encrypted with the same key stream byte. After the stream encryption, the encrypted $m\times n$ sub-blocks are randomly permutated with a permutation key. Since the correlation between the neighboring pixels in each sub-block can be well preserved in the encrypted domain, most of those previously proposed RDH schemes can be applied to the encrypted image directly. One of the main merits of the proposed framework is that the RDH scheme is independent of the image encryption algorithm. That is, the server manager (or channel administrator) does not need to design a new RDH scheme according to the encryption algorithm that has been conducted by the content owner; instead, he/she can accomplish the data hiding by applying the numerous RDH algorithms previously proposed to the encrypted domain directly.
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The codebook design which determines the quality of the encoded images is an important problem in the vector quantisation technique. The Linde–Buzo–Gray (LBG) technique is a widely used algorithm in the codebook design. However, LBG algorithm is very sensitive to the initial codebook and tends to trap to the local minimum. In this study, a high‐quality initial codebook design method is proposed. The proposed method utilises both the mean characteristic value and variance characteristic value of training vectors to divide the training vectors into groups. Then codewords are selected from each group to generate an initial codebook. The experimental results demonstrate that the authors proposed method has a better performance in the initial codebook than that of the related methods.
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Abstract Sparse code multiple access (SCMA) is an emerging technology developed to meet the requirements of 5G and 6G communications and improve the spectral efficiency of systems. The key behind SCMA technology is the design of its codebook method, particularly the design of the mother codebook method, which forms the basis of excellent user codebook design. Considering the limitations of existing mother codebook methods, a constellation evolution mother codebook design method is proposed here. Odd and even constellations are derived using the proposed method, and a multi-dimensional rotation angle is established. Then, the excellent mother constellations (mother codebook) are reconstructed. The proposed mother codebook design method demonstrates excellent performance in terms of the bit error rate and is found to be superior to existing codebook methods. It can provide a universal mother codebook for user codebooks, thus yielding excellent codebooks for efficient SCMA applications and establishing a technical basis for efficient 5G and 6G applications.
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Encrypting technique is a kind of most common and important technique in network's safety technique. It is most unsuccessful when the significant information transmitted in plaintext forms on network, so we need to encrypt datas. This text summarizes the method of encrypt data, encrypting forms and the application of encrypting technique.
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Zero-forcing precoding
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In order to solve the security problem during the transmission of digital image,according to the analysis of traditional image encryption using high-dimension chaotic system,an improved algorithm of image encryption is given.It combines the methods of position shuffling and pixel value substituting in iterations,and makes the encrypted datastream having relation to the plaintext.It resolved the bugs of traditional algorithm in application.The results of theoretical analysis and simulated experiment show that the algorithm guarantees the security of encryption effectively and excellent effect of encryption,the encrypted result varies sensitively with any minimal changes of the initial secret key and the plaintext,the value of adjacent pixels satisfy zero correlation,showing that the algorithm is feasible,security and easy to operate.
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Shuffling
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Visual codebook has been popular in object classification as well as action analysis. However, its performance is often sensitive to the codebook size that is usually predefined. Moreover, the codebook generated by unsupervised methods, e.g., K-means, often suffers from the problem of ambiguity and weak efficiency. In other words, the visual codebook contains a lot of noisy and/or ambiguous words. In this paper, we propose a novel method to address these issues by constructing a compact but effective visual codebook using sparse reconstruction. Given a large codebook generated by K-means, we reformulate it in a sparse manner, and learn the weight of each word in the original visual codebook. Since the weights are sparse, they naturally introduce a new compact codebook. We apply this compact codebook to action recognition tasks and verify it on the widely used Weizmann action database. The experimental results show clearly the benefits of the proposed solution.
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