10928867
Nonlinearity and Propagation Characteristics of Balanced Boolean Functions
Abstract Three important criteria for cryptographically strong Boolean functions are balance, nonlinearity, and the propagation criterion. The main contributions of this paper are to reveal a number of interesting properties of balance and nonlinearity, and to study systematic methods for constructing Boolean functions that satisfy some or all of the three criteria. We show that concatenating, splitting, modifying, and multiplying (in the sense of Kronecker) sequences can yield balanced Boolean functions with a very high nonlinearity. In particular, we show that balanced Boolean functions obtained by modifying and multiplying sequences achieve a nonlinearity higher than that attainable by any previously known construction method. We also present methods for constructing balanced Boolean functions that are highly nonlinear and satisfy the strict avalanche criterion (SAC). Furthermore we present methods for constructing highly nonlinear balanced Boolean functions satisfying the propagation criterion with respect to all but one or three vectors. A technique is developed to transform the vectors where the propagation criterion is not satisfied in such a way that the functions constructed satisfy the propagation criterion of high degree while preserving the balance and nonlinearity of the functions. The algebraic degrees of functions constructed are also discussed.
105147
Digital Watermarking Robust Against JPEG Compression
Digital watermarking has been considered as an important technique to protect the copyright of digital content. For a digital watermarking method to be effective, it is essential that a watermark embedded in a still or moving image resists against various attacks ranging from compression, filtering to cropping. As JPEG is a dominant still image compression standard for Internet applications, digital watermarking methods that are robust against the JPEG compression are especially useful. Most digital watermarking methods proposed so far work by modulating pixels/coefficients without considering the quality level of JPEG, which renders watermarks readily removable. In this paper, we propose a new method that actively uses the JPEG quality level as a parameter in embedding a watermark into an image. A useful feature of the new method is that the watermark can be extracted even when the image is compressed using JPEG.
14223982
Statistical Database Modeling for Privacy Preserving Database Generation
Testing of database applications is of great importance. Although various studies have been conducted to investigate testing techniques for database design, relatively few efforts have been made to explicitly address the testing of database applications which requires a large amount of representative data available. As testing over live production databases is often infeasible in many situations due to the high risks of disclosure of confidential information or incorrect updating of real data, in this paper we investigate the problem of generating synthetic database based on a-priori knowledge about production database. Our approach is to fit general location model using various characteristics (e.g., constraints, statistics, rules) extracted from production database and then generate synthetic data using model learnt. As characteristics extracted may contain information which may be used by attacker to derive some confidential information, we present a disclosure analysis method which is based on cell suppression technique. Our method is effective and efficient to remove aggregate private information during data generation.
36265866
A Security Acceleration Using XML Signcryption Scheme in Mobile Grid Web Services
Today's grid architecture encompasses a far greater breadth of applications than the traditional grid, which focused on distributed applications processing large amounts of data. Newer grid applications are more data-centric and more focused on distributed services. As these trends, mobile internet and the grid, are likely to find each other the resource constraints that wireless devices pose today affect the level of interoperability between them. The goal of this paper is to investigate how well the most limited wireless devices can make the use of grid security services. This paper describes a novel security approach on fast mobile grid services based on current mobile web services platform environment using XML signcryption mechanism.
9346791
On the Security of RSA with Primes Sharing Least-Significant Bits
Abstract.We investigate the security of a variant of the RSA public-key cryptosystem called LSBS-RSA, in which the modulus primes share a large number of least-significant bits. We show that low public-exponent LSBS-RSA is inherently resistant to Partial Key Exposure (PKE) attacks in which least-significant bits of the secret exponent are revealed to the attacker, and in particular that the Boneh-Durfee-Frankel PKE attack [5] on low public-exponent RSA is less effective for LSBS-RSA systems than for standard RSA. On the other hand, we show that large public-exponent LSBS-RSA is more vulnerable to such attacks than standard RSA. An application to server-aided RSA signature generation is proposed.
7417533
Cryptographically resilient functions
This correspondence studies resilient functions which have applications in fault-tolerant distributed computing, quantum cryptographic key distribution, and random sequence generation for stream ciphers. We present a number of new methods for synthesizing resilient functions. An interesting aspect of these methods is that they are applicable both to linear and nonlinear resilient functions. Our second major contribution is to show that every linear resilient function can be transformed into a large number of nonlinear resilient functions with the same parameters. As a result, we obtain resilient functions that are highly nonlinear and have a high algebraic degree.
6047065
Efficiently Supporting Structure Queries on Phylogenetic Trees
With phylogenetics becoming increasingly important in biomedical research, the number of phylogenetic studies is increasing rapidly and huge mount of phylogenetic data has been generated and stored in databases. How to efficiently extract information from the data has become an important research problem. In this paper, we focus on a class of important queries on phylogenetic trees: structure queries which include least common ancestor, minimal spanning clade, tree pattern match and tree projection. After analyzing the characteristics of the phylogenetic tree as well as structure queries, we propose a storage system based on labeling using RDBMS and design algorithms for query evaluation. We implement these algorithms and compare them with existing techniques. Performance studies prove the efficiency of our strategy.
16436338
Applying Decomposition Methods to Crossword Puzzle Problems
Structural decomposition methods have been proposed for identifying tractable Constraint Satisfaction Problems (CSPs)[1-5]. The basic principle is to decompose a CSP into tree-structured sub-problems. The subproblems are solved independently, then the original CSP is solved in a backtrack-free manner after the tree structure is made arc-consistent, as described in [1]. In [5], we proposed four decomposition methods: HINGE+, CUT, TRAVERSE, and CaT and tested these methods on randomly generated CSPs. We compare these techniques on instances of the fully interlocked Crossword Puzzle Problems (CPPs) [6] taken from a public library [7] and identify special cases of the constraint hypergraphs where some decomposition techniques yield better results than others although in general the opposite holds. Our future work includes: 1)Identifying more such configurations, and building hybrid decompositions techniques that exploit this information; 2)Tailoring existing decomposition methods for fully interlocked CPPs so that every sub-problem, after backtrack search, has few solutions; and 3)Designing a heuristic for applying local search for fully interlocked CPPs. This work is supported by CAREER Award #0133568 from the National Science Foundation.
6457216
A CMOS Direct-Digital BPSK Modulator Using an Active Balun and Common-Gate Switches
A 0.18 mum CMOS binary phase shift keying (BPSK) modulator circuit is proposed and demonstrated that can achieve high data rates and strong carrier suppression while having low DC power consumption and a very compact layout. The modulator accepts a single-ended microwave signal (2.4 GHz) and converts it to a balanced signal using an active balun. Complementary common-gate switches are then used to select one of the two balun outputs in correspondence with the digital data to produce BPSK modulation. Excellent performance is obtained with measured phase and amplitude errors of less than 1deg and 0.1 dB, respectively, and data rates up to 200 Mbps with a carrier frequency of 2.4 GHz. The insertion loss for the modulator is approximately 3 dB. Additionally, the active balun provides input matching and obtains an input reflection coefficient of -13 dB. The circuit layout area is 310 mumtimes260 mum and the power consumption is 7.2 mW.
13603559
A new metric based on extended spatial frequency and its application to DWT based fusion algorithms
A new quantitative metric is proposed to objectively evaluate the quality of fused imagery. The measured value of the proposed metric is used as feedback to a fusion algorithm such that the image quality of the fused image can potentially be improved. This new metric, called the ratio of spatial frequency error (rSFe), is derived from the definition of a previous measure termed ''spatial frequency'' (SF) that reflects local intensity variation. In this work, (1) the concept of SF is first extended by adding two diagonal SFs, then, (2) a reference SF (SF"R) is computed from the input images, and finally, (3) the error SF (SF"E) (subtracting the fusion SF from the reference SF), or the ratio of SF error (rSFe=SF"E/SF"R), is used as a fusion quality metric. The rSFe (which can be positive or negative) indicates the direction of fusion error-over-fused (if rSFe>0) or under-fused (if rSFe<0). Thus, the rSFe value can be back propagated to the fusion algorithm (BP fusion), thereby directing further parameter adjustments in order to achieve a better-fused image. The accuracy of the rSFe is verified with other quantitative measurements such as the root mean square error (RMSE) and the image quality index (IQI), as well as with a qualitative perceptual evaluation based on a standard psychophysical paradigm. An advanced wavelet transform (aDWT) method that incorporates principal component analysis (PCA) and morphological processing into a regular DWT fusion algorithm is implemented with two adjustable parameters-the number of levels of DWT decompositions and the length of the selected wavelet. Results with aDWT were compared to those with a regular DWT and with a Laplacian pyramid. After analyzing several inhomogeneous image groups, experimental results showed that the proposed metric, rSFe, is consistent with RMSE and IQI, and is especially powerful and efficient for realizing the iterative BP fusion in order to achieve a better image quality. Human perceptual assessment was measured and found to strongly support the assertion that the aDWT offers a significant improvement over the DWT and pyramid methods.
1828938
Crimson: a data management system to support evaluating phylogenetic tree reconstruction algorithms
Evolutionary and systems biology increasingly rely on the construction of large phylogenetic trees which represent the relationships between species of interest. As the number and size of such trees increases, so does the need for efficient data storage and query capabilities. Although much attention has been focused on XML as a tree data model, phylogenetic trees differ from document-oriented applications in their size and depth, and their need for structure-based queries rather than path-based queries.This paper focuses on Crimson, a tree storage system for phylogenetic trees used to evaluate phylogenetic tree reconstruction algorithms within the context of the NSF CIPRes project. A goal of the modeling component of the CIPRes project is to construct a huge simulation tree representing a "gold standard" of evolutionary history against which phylogenetic tree reconstruction algorithms can be tested.In this demonstration, we highlight our storage and indexing strategies and show how Crimson is used for benchmarking phylogenetic tree reconstruction algorithms. We also show how our design can be used to support more general queries over phylogenetic trees.