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1st International Conference on Computer Science and Information Technology

作者： Sabyasachi, Samanta Saurabh, Dutta Haldia Inst Technol Haldia WB India Roy Engn Coll Durgapur Durgapur W Bengal India

ISBN: (纸本)9783642178771

In this paper, we have assigned a unique range for both, a number of characters and groups using the characters. Long textual message which have to encrypt, is subdivided into a number of groups with n characters. Then the group of characters is encrypted into two floating point numbers by using arithmetic coding, where they are automatically compressed. Depending on key, the data bits from text are placed to some suitable nonlinear pixel and bit positions about the image. In the proposed technique, the key characters are alphanumeric and key length is also variable. Using the symmetric key technique again they are decrypted into original text message from the watermarked image.

关键词： pixel invisible digital watermarking arithmetic coding symmetric key nonlinear function

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Cipherstream Covering for Secure Data Compression

Cipherstream Covering for Secure Data Compression

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IEEE International Conference on Systems, Man and Cybernetics (SMC)

作者： Metzler, Richard E. L. Agaian, Sos S. Univ Texas San Antonio Dept Elect & Comp Engn San Antonio TX 78249 USA

ISBN: (纸本)9781457706530

Because of its ability to compress and encrypt plaintext simultaneously, embedment of stream cipher rules into Elias-type entropy encoders provides a fast and secure means of data compression with the ability to hide cipherstream information in the case of a known plaintext attack. Compression and security improve by continually updating the statistical representation of the plaintext. Simulations on images from a variety of classes compare the compression ratios and computational costs of the novel system to those of traditional compression-followed-by-encryption methods.

关键词： compression encryption stream cipher security arithmetic coding range coding Elias coding comcryption concryption

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Safe Software Processing by Concurrent Execution in a Real-Time Operating System

Safe Software Processing by Concurrent Execution in a Real-T...

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International Conference on Applied Electronics

作者： Raab, Peter Kraemer, Stefan Mottok, Juergen Meier, Hans Racek, Stanislav Regensburg Univ Appl Sci Fac Elect & Informat Technol Seybothstr 2 D-93053 Regensburg Germany Univ West Bohemia Fac Sci Appl Plzen 30614 Czech Republic

ISBN: (纸本)9788070439876

The requirements for safety-related software systems increases rapidly. To detect arbitrary hardware faults, there are applicable coding mechanism, that add redundancy to the software. In this way it is possible to replace conventional multi-channel hardware and so reduce costs. arithmetic codes are one possibility of coded processing and are used in this approach. A further approach to increase fault tolerance is the multiple execution of certain critical parts of software. This kind of time redundancy is easily realized by the parallel processing in an operating system. Faults in the program flow can be monitored. No special compilers, that insert additional generated code into the existing program, are required. The usage of multi-core processors would further increase the performance of such multi-channel software systems. In this paper we present the approach of program flow monitoring combined with coded processing, which is encapsulated in a library of coded data types. The program flow monitoring is indirectly realized by means of an operating system.

关键词： program flow software process improvement real time operating system parallel execution Software systems Operating systems arithmetic coding redundancy Multi-core processors PARALLEL PROCESSING (COMPUTERS) Fault tolerance computer software

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A greedy renormalization method for arithmetic coding

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IEEE TRANSACTIONS ON COMMUNICATIONS 2007年第8期55卷 1494-1503页

作者： Jia, Yunwei Yang, En-hui He, Da-ke Chan, Steven Adv Micro Devices Inc Markham ON L3T 7X6 Canada Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada IBM Corp Thomas J Watson Res Ctr Yorktown Hts NY 10598 USA SlipStream Data Inc Waterloo ON N2L 5Z5 Canada

A typical arithmetic coder consists of three steps: range calculation, renormalization, and probability model updating. In this paper, we propose and analyze from an information theoretic point of view a greedy renormalization method, which has two components: greedy thresholding and greedy outputting. The method significantly reduces the computational complexity of the renormalization step of arithmetic coding by 1) using the greedy thresholding to minimize the number of renormalizations required to encode a sequence and 2) using the greedy outputting to minimize the number of operations within each renormalization. The method is particularly suitable for binary arithmetic coding (BAC). Two BAC algorithms based on this method are presented. The first algorithm replaces the renormalization method in the TOIS BAC [21 with the greedy renormalization method, and keeps other parts of the TOIS BAC unchanged. For binary independent and identically distributed (i.i.d.) sources with the probability of the less probable symbol ranging from 0.01-0.45, over 20% gain in speed (on average), and less than 1% loss in compression rate (in the worst case) are observed in the experiments. The second algorithm combines the greedy renormalization method with the QM-Coder. On an average, 30% gain in speed and 3% gain in compression rate are observed in the experiments.

关键词： arithmetic coding computational complexity data compression source coding

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Improvement of Security and Feasibility for Chaos-Based Multimedia Cryptosystem

Improvement of Security and Feasibility for Chaos-Based Mult...

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11th International Conference on Computational Science and Its Applications (ICCSA)

作者： Chen, Jianyong Zhou, Junwei Shenzhen Univ Dept Comp Sci & Technol Shenzhen 518060 Peoples R China

ISBN: (纸本)9783642218989

Nonlinear dynamic filter (NDF) has been used in chaos-based multimedia cryptosystem. However, our study shows that the key of randomized arithmetic coding (RAC) based on NDF can be successfully recovered under chosen plaintext attack. Moreover, current ciphertext block can't be decoded unless preceding plaintext is available. In order to enhance the security and feasibility used in multimedia applications, the algorithm is improved by building a new correlation between ciphertext and coefficients. Its security is enhanced that can effectively resist chosen plaintext attack. Its feasibility is also improved that can decode ciphertext block without availability of preceding plaintext with which a user can play multimedia data starting at any place. The analysis and simulations show that the improved algorithm can evidently enhance both security and feasibility

关键词： Chaos Cryptography Security arithmetic coding

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Symbolic Dynamics of the Weyl Chamber Flow

Symbolic Dynamics of the Weyl Chamber Flow

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作者： Egorov, Arseni PennState University Libraries

学位级别：Doctor of Philosophy

This thesis studies codings of orbits of Weyl chamber ﬂows on symmetric spacesof non-compact type.
Let H be the hyperbolic plane with constant curvature −1 and Γ be a Fuchsiangroup of ﬁnite covolume. Let D be a Dirichlet domain of Γ on H. The main resultshows that the set of cutting sequences of all geodesics in the sense of Morse withrespect to the tessellation of H, formed by the sets gD, g ∈ Γ, is a topologicalMarkov chain if and only if D does not have vertices in H.
Also, a background is provided for the study of generalization of continuedfractions to higher dimensions. So-called arithmetic Gauss coding of geodesics onH is described along with its relation with the minus continued fractions. H is aparticular case of a symmetric space of non-compact type, H = SL₂R/SO₂R, andthe geodesic ﬂow on H implements the Weyl chamber ﬂow on it. A generalizationof the minus continued fractions was suspected by S. Katok and A. Katok to exist,which involves orbits of Weyl chamber ﬂows on symmetric spaces of non-compacttype SL_nR/SO_nR and their compactiﬁcations.

关键词： topological Markov chains geodesic flow Weyl chamber flow geometric coding arithmetic coding symmetric spaces continued fractions

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An FFGA-based implementation of multi-alphabet arithmetic coding

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2007年第8期54卷 1678-1686页

作者： Mahapatra, Sudipta Singh, Kuldeep Indian Inst Technol Dept Elect & Elect Commun Kharagpur 721302 W Bengal India

A fully parallel implementation of the multi-alphabet arithmetic-coding algorithm, an integral part of many lossless data compression systems, had so far eluded the research community. Although schemes were in existence for performing the encoding operation in parallel, the data dependencies involved in the decoding phase prevented its parallel execution. This paper presents a scheme for the parallel-pipelined implementation of both the phases of the arithmetic-coding algorithm for multisymbol alphabets in high-speed programmable hardware. The compression performance of the proposed scheme has been evaluated and compared with an existing sequential implementation in terms of average compression ratio as well as the estimated execution time for the Canterbury Corpus test set of files. The proposed scheme facilitates hardware realization of both coder and decoder modules by reducing the storage capacity necessary for maintaining the modeling information. The design has been synthesized for Xilinx field-programmable gate arrays and the synthesis results obtained are encouraging, paving the way for further research in this direction.

关键词： arithmetic coding decoding higher order context models lossless data compression parallel architectures

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Ratio‐modified block truncation coding algorithms for reduced bitrates

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The Journal of Photographic Science 2011年第1期59卷 25-31页

Block truncation coding (BTC) technique is a simple and fast image compression algorithm since complicated transforms are not used. The principle used in BTC algorithm is to use two‐level quantiser that adapts to local properties of the image while preserving the first‐ or first‐ and second‐order statistical moments. The parameters transmitter or stored in the BTC algorithm are statistical moments and bitplane yielding good quality images at a bitrate of 2 bits per pixel (bpp). In this paper, two algorithms for modified BTC (MBTC) are proposed for reducing the bitrate below 2 bpp. The principal used in the proposed algorithms is to use the ratio of moments which is a smaller value when compared to absolute moments. The ratio values are then entropy coded. The bitplane is also coded to remove the correlation among the bits. The proposed algorithms are compared with MBTC and the algorithms obtained by combining JPEG standard with MBTC in terms of bitrate, peak signal‐to‐noise ratio (PSNR) and subjective quality. It is found that the reconstructed images obtained using the proposed algorithms yield better results.

关键词： image coding block truncation coding JPEG arithmetic coding bitplane coding

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Distributed arithmetic coding

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IEEE COMMUNICATIONS LETTERS 2007年第11期11卷 883-885页

作者： Grangetto, Marco Magli, Enrico Ohmo, Gabriella Politecn Torino Dipartimento Elettr I-10129 Turin Italy

We propose a distributed binary arithmetic coder for Slepian-Wolf coding with decoder side information, along with a soft joint decoder. The proposed scheme provides several advantages over existing schemes, and its performance is equal to or better than that of an equivalent scheme based on turbo codes at short and medium block lengths.

关键词： distributed source coding arithmetic coding Slepian-Wolf coding Wyner-Ziv coding compression

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A flexible JPEG2000 image encryption based on arithmetic coding

A flexible JPEG2000 image encryption based on arithmetic cod...

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International Symposium on Intelligent Signal Processing and Communication Systems

作者： Ou, Yang Lee, Won-Young Rhee, Kyung Hyune Pukyong Natl Univ Dept Informat Security Pusan South Korea Pukyong Natl Univ Div Elect Comp & Telecommun Engn Busan 608737 South Korea

ISBN: (纸本)9781424414468

In this paper, we propose a flexible JPEG2000 image encryption based on arithmetic coding which combines both compression and encryption. Particularly, we randomly add a subinterval to the probability interval in each coding step during the iterative process of arithmetic coder. The range of this subinterval. can be flexibly adjusted depending on the properties of different applied environments. Furthermore, our approach supports backward compatibility so that an encryption-unaware format-compliant player can play the encrypted code stream without any crash. Notably, our algorithm achieves a very simple switch between the standard compression model and our joint model.

关键词： arithmetic coding joint compression and encryption MQ coder JPEG2000

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