5900866
Breaking network security based on synchronized chaos
Very recently, the use of chaos synchronization as a means of masking information data in a network has been proposed. Although it is claimed that the security breach is not possible and that the proposed encryption approach can be used to secure communications over Internet, we prove that these claims are unfounded, breaking the cryptosystem in different ways.
3106412
On the Design of Perceptual MPEG-Video Encryption Algorithms
In this paper, some existing perceptual encryption algorithms of MPEG videos are reviewed and some problems, especially security defects of two recently proposed MPEG-video perceptual encryption schemes, are pointed out. Then, a simpler and more effective design is suggested, which selectively encrypts fixed-length codewords in MPEG-video bit streams under the control of three perceptibility factors. The proposed design is actually an encryption configuration that can work with any stream cipher or block cipher. Compared with the previously-proposed schemes, the new design provides more useful features, such as strict size-preservation, on-the-fly encryption and multiple perceptibility, which make it possible to support more applications with different requirements. In addition, four different measures are suggested to provide better security against known/chosen-plaintext attacks
18473631
Cryptanalysis of a Chaotic Neural Network Based Multimedia Encryption Scheme
Recently, Yen and Guo proposed a chaotic neural network (CNN) for signal encryption, which was suggested as a solution for protection of digital images and videos. The present paper evaluates the security of this CNN-based encryption scheme, and points out that it is not secure from the cryptographical point of view: 1) it can be easily broken by known/chosen-plaintext attacks; 2) its security against the brute-force attack was much over-estimated. Some experiments are shown to support the results given in this paper. It is also discussed how to improve the encryption scheme.
218270
Cryptanalysis of a multistage encryption system
This paper analyzes the security of a new multistage encryption system (MES) recently proposed in ISCAS'2004. It is found that MES is insecure against a differential chosen-plaintext/ciphertext attack. Experiments are given to support the proposed attack. It is also pointed out that the security of MES against brute-force attacks is not sufficiently high.
2501834
On the security of the Yen-Guo's domino signal encryption algorithm (DSEA)
Recently, a new domino signal encryption algorithm (DSEA) was proposed for digital signal transmission, especially for digital images and videos. This paper analyzes the security of DSEA, and points out the following weaknesses: (1) its security against the brute-force attack was overestimated; (2) it is not sufficiently secure against ciphertext-only attacks, and only one ciphertext is enough to get some information about the plaintext and to break the value of a sub-key; (3) it is insecure against known/chosen-plaintext attacks, in the sense that the secret key can be recovered from a number of continuous bytes of only one known/chosen plaintext and the corresponding ciphertext. Experimental results are given to show the performance of the proposed attacks, and some countermeasures are discussed to improve DSEA.
2190827
Chosen-Plaintext Cryptanalysis of a Clipped-Neural-Network-Based Chaotic Cipher
At ISNN'04, a novel symmetric cipher was proposed, by combining a chaotic signal and a clipped neural network (CNN) for encryption. The present paper analyzes the security of this chaotic cipher against chosen-plaintext attacks, and points out that this cipher can be broken by a chosen-plaintext attack. Experimental analyses are given to support the feasibility of the proposed attack.
1883250
Accelerated, high-quality refraction computations for volume graphics
We present an efficient framework for the high-quality rendering of discretely sampled surface-based objects with refractive effects. This requires an accurate estimation of the refraction coefficients, paired with efficient and accurate surface detection, space traversal, and backdrop image sampling. Our framework achieves these goals, by employing a high-quality spline-based filter in conjunction with a novel filtered octree space decomposition with pre-classified cells that is carefully matched to the filter and voxel neighborhood characteristics. Here, we benefit greatly from the non-negativity of the B-spline kernel. Finally, we describe an innovative scheme that achieves the high quality of pixel super-sampling on a flat backdrop plane without the overhead of tracing the actual rays across the refractive object.
14078750
A Novel Hierarchical Approach to Image Retrieval Using Color and Spatial Information
A novel hierarchical approach to image retrieval is proposed. First, a color label histogram is used to effectively filter out the images that are not similar to the query image in color. The proposed color label histogram built by categorizing the pixel colors is computationally much more efficient compared to other approaches. Next, the class parameters of those images passing the first filter are used to identify the images similar to the query image in spatial layout. These class parameters are obtained automatically from the proposed unsupervised segmentation algorithm. Moreover, the wavelet decomposition coefficients are used to generate the initial partition for the segmentation algorithm. It doubles the segmentation performance. At the last stage, all images passing two filters are ranked based on the total normalized distance in color and spatial layout. The experiments show the effectiveness and efficiency of our approach.
43890946
VRML-Based 3D Collaborative GIS: A Design Perspective
Recent advance of technology has made it possible to view and simply manipulate 3D representations of spatial information over the Internet. 3D visualization, however, imposes many unique requirements to software design and implementation, as well as supporting data. Furthermore, current development of 3D modelling and visualization of spatial information mostly focus on single user platform. This paper presents our discussion on the design and development of an Internet-based 3D collaborative GIS system, which support real-time multi-user collaboration. While the prototype development is ongoing, some design issues are discussed based on our preliminary work. ...
15838609
Linear network coding
Consider a communication network in which certain source nodes multicast information to other nodes on the network in the multihop fashion where every node can pass on any of its received data to others. We are interested in how fast each node can receive the complete information, or equivalently, what the information rate arriving at each node is. Allowing a node to encode its received data before passing it on, the question involves optimization of the multicast mechanisms at the nodes. Among the simplest coding schemes is linear coding, which regards a block of data as a vector over a certain base field and allows a node to apply a linear transformation to a vector before passing it on. We formulate this multicast problem and prove that linear coding suffices to achieve the optimum, which is the max-flow from the source to each receiving node.
2365541
Applying Information Retrieval Technology to Incremental Knowledge Management
Knowledge Management has been an important task in large organizations. It is rather costly to convert the huge amounts of unstructured information produced by legacy applications to formally described knowledge. In this paper we present a knowledge management framework that is based on improved information retrieval systems. By introducing ontologies into IR domain, the framework can recognize semantics of concepts and obtain limited reasoning ability. We expect that the framework would provide organizations a practical and cost-effective way of incremental knowledge management.