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The PASCAL Visual Object Classes Challenge

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

The number of changing pixel rate (NPCR) and the unified averaged changed intensity (UACI) are two most common quantities used to evaluate the strength of image encryption algorithms/ciphers with respect to differential attacks. Conventionally, a high NPCR/UACI score is usually interpreted as a high resistance to differential attacks. However, it is not clear how high NPCR/UACI is such that the image cipher indeed has a high security level. In this paper, we approach this problem by establishing a mathematical model for ideally encrypted images and then derive expectations and variances of NPCR and UACI under this model. Further, these theoretical values are used to form statistical hypothesis NPCR and UACI tests. Critical values of tests are consequently derived and calculated both symbolically and numerically. As a result, the question of whether a given NPCR/UACI score is sufficiently high such that it is not discernible from ideally encrypted images is answered by comparing actual NPCR/UACI scores with corresponding critical values. Experimental results using the NPCR and UACI randomness tests show that many existing image encryption methods are actually not as good as they are purported, although some methods do pass these randomness tests.

NPCR and UACI Randomness Tests for Image Encryption

A new 1D chaotic system for image encryption

The theory of chaos has been widely used for image encryption because of its excellent cryptography characteristics and intrinsic features of image. In this paper, a new image encryption scheme based on chaos is proposed. This new scheme using the principle of magic cube transformation to shuffle the position of image pixels and modify the pixel values with pseudorandom sequences generated by compound chaotic maps. The simulations results show that the image encrypted by this new scheme can not be recognized. Furthermore, the proposed scheme is secure against almost all kinds of attacks.

A Chaotic Image Encryption Scheme Based on Magic Cube Transformation

With a chaotic system being divided into linear and nonlinear parts, a new approach is presented to realize generalized chaos synchronization by using feedback control and parameter commutation. Based on a linear transformation, the problem of generalized synchronization (GS) is transformed into the stability problem of the synchronous error system, and an existence condition for GS is derived. Furthermore, the performance of GS can be improved according to the configuration of the GS velocity. Further generalization and appropriation can be acquired without a stability requirement for the chaotic system's linear part. The Lorenz system and a hyperchaotic system are taken for illustration and verification and the results of the simulation indicate that the method is effective.

A new approach to generalized chaos synchronization based on the stability of the error system

Cascading failure is fatal in applications and its investigation is essential and therefore became a focal topic in the field of complex networks in the last decade. In this paper, a cascading failure model is established for interconnected networks and the associated data-packet transport problem is discussed. A distinguished feature of the new model is its utilization of fuzzy information in resisting uncertain failures and malicious attacks. We numerically find that the giant component of the network after failures increases with tolerance parameter for any coupling preference and attacking ambiguity. Moreover, considering the effect of the coupling probability on the robustness of the networks, we find that the robustness of the assortative coupling and random coupling of the network model increases with the coupling probability. However, for disassortative coupling, there exists a critical phenomenon for coupling probability. In addition, a critical value that attacking information accuracy affects the network robustness is observed. Finally, as a practical example, the interconnected AS-level Internet in South Korea and Japan is analyzed. The actual data validates the theoretical model and analytic results. This paper thus provides some guidelines for preventing cascading failures in the design of architecture and optimization of real-world interconnected networks.

Fuzzy-information-based robustness of interconnected networks against attacks and failures

A new integral sliding mode control strategy for high-speed networks operating in asynchronous transfer mode (ATM) is derived to cope with the congestion problem in network flow control. The novelty of the proposed design solution stem from allowing high-speed networks to have simultaneously acting multiple time-varying input delays, uncertainties and time-varying perturbations. A delay-dependent condition is derived via the linear matrix inequality approach that guarantees both the asymptotic stability and a prescribed H ∞-performance level of the closed-loop system in sliding mode dynamics when perturbations of available bit-rate bandwidth occur. These new results are obtained with no restriction on the derivative of the time-varying delays hence are less conservative than the existing ones. This control scheme does achieve both of the main goals in ATM network traffic, namely convergence of the queue length to the desired steady-state status and the weighted fairness condition. The application to bench...

Integral sliding mode controller design for congestion problem in ATM networks

In recent years, amounts of permutation-diffusion architecture-based image cryptosystems have been proposed. However, the key stream elements in the diffusion procedure are merely depending on the secret key that is usually fixed during the whole encryption process. Cryptosystems of this type suffer from unsatisfactory encryption speed and are considered insecure upon known/chosen plaintext attacks. In this paper, an efficient diffusion scheme is proposed. This scheme consists of two diffusion procedures, with a supplementary diffusion procedure padded after the normal diffusion. In the supplementary diffusion module, the control parameter of the selected chaotic map is altered by the resultant image produced after the normal diffusion operation. As a result, a slight difference in the plain image can be transferred to the chaotic iteration and bring about distinct key streams, and hence totally different cipher images will be produced. Therefore, the scheme can remarkably accelerate the diffusion effect of the cryptosystem and will effectively resist known/chosen plaintext attacks. Theoretical analyses and experimental results prove the high security performance and satisfactory operation efficiency of the proposed scheme.

https://downloads.hindawi.com/journals/mpe/2014/427349.pdf

Hai Yu

Papers

A Chaotic Image Encryption Scheme Based on Magic Cube Transformation

A new approach to generalized chaos synchronization based on the stability of the error system

Fuzzy-information-based robustness of interconnected networks against attacks and failures

Integral sliding mode controller design for congestion problem in ATM networks

An Efficient Diffusion Scheme for Chaos-Based Digital Image Encryption