Daoshun Wang

Image universal steganalysis based on best wavelet packet decomposition

Based on the best wavelet packet decomposition of images, a new universal steganalysis method with high detection correct ratio is proposed. First, the best wavelet packet decomposition of image based on the Shannon entropy information cost function is made. Second, high order absolute characteristic function moments of histogram extracted from the coefficient subbands obtained by best wavelet packet decomposition are regarded as features. Finally, these features are processed and a back-propagation (BP) neural network is designed to classify original and stego images. Three different steganalysis algorithms for three different cases of background and application condition are presented. To validate the performance of the proposed method, a series of experiments are made for six kinds of typical steganography methods, i.e. LSB, LTSB, PMK, Jsteg, F5 and JPHide. Results show that, the average detection accuracy of the proposed method exceeds at least 6.4% and up to 15.4% and has a better universal performance than its closest competitors. Furthermore, the proposed method can provide reference for designing the pattern recognition and classification algorithm based on best wavelet packet decomposition.

A scalable authentication model based on public keys

To solve the scalability problems of the identity authentication model based on CA for application in large distributed networks, adopting a rigorous binary tree code algorithm, we present a distributed identity authentication model based on public keys. The advantages of our model are described as follows: First, it has good scalability and is suitable for large-scale distributed networks. Second, the authentication path is short, with no more than two entities intervening. Third, it does not require users to inquire about certificate revocation lists.

Multi secret image color visual cryptography schemes for general access structures

Abstract In the proposed visual cryptography schemes for general access structures, the single secret image black-and-white visual cryptography schemes with meaningful shares have been constructed, in which the shares are innocent looking images. The meaningful shares have not been realized in single secret image color schemes; neither have the multi secret images color schemes. In this paper, the multi secret images color visual cryptography schemes for general access structures with meaningful shares are constructed by the method of matrix concatenation, the pixel expansion is obtained, and the validity of the scheme is proven. In our scheme, the different combination of meaningful color shares can be used to recover distinct color secret images. The multi secret images black-and-white visual cryptography scheme is a special case of our color scheme. *Supported by National Natural Science Foundation of China (Grant No. 90304014) and the Major State Basic Research Development Program of China (Grant No. ...

A distributed expansible authentication model based on Kerberos

There is a potential server bottleneck problem when the Kerberos model is applied in large-scale networks because the model uses centralized management. To enlarge its application scope, researchers must consider how to build a trust relation among those Kerberos servers located on different isolated domains, but have not provided a way to prevent the potential bottleneck that can occur with Kerberos servers. With the development of across-domain authentication techniques, the local server bottleneck problem has not been alleviated; in fact, it has become more serious. Adopting the rigorous binary tree code algorithm, we present an authentication model based on Kerberos. Compared with similar models, our model has several advantages. First, it overcomes the potential server bottleneck problem and can balance the load automatically. Second, it can process across-domain authentication and enlarge the authentication boundary. Finally, its authentication path is short, with no more than two Kerberos servers being involved when authenticating a user.

Shift visual cryptography scheme of two secret images

Abstract A new visual cryptography scheme of two secret images, which is named the shift visual cryptography of two secret images, is given. The compound function family of a general construction model is also introduced. The uniqueness and validity of this model are proved, and the minimum rows and columns for realizing the scheme are obtained. Compared with visual cryptography of one secret image, the shift visual cryptography scheme can share two secret images with the same size of pixels expansion without losing the contrast. It has randomness and various forms, and furthermore, we can also visually recover two secret images even if the two shares are different in form and color.

Cryptanalysis of RSA for a special case with d >e

In this paper, we study the RSA public key cryptosystem in a special case with the private exponent d larger than the public exponent e. When N0.258 ⩽ e ⩽ N0.854, d > e and satisfies the given conditions, we can perform cryptanalytic attacks based on the LLL lattice basis reduction algorithm. The idea is an extension of Boneh and Durfee’s researches on low private key RSA, and provides a new solution to finding weak keys in RSA cryptosystems.

Symmetric cryptographic protocols for extended millionaires’ problem

Yao’s millionaires’ problem is a fundamental problem in secure multiparty computation, and its solutions have become building blocks of many secure multiparty computation solutions. Unfortunately, most protocols for millionaires’ problem are constructed based on public cryptography, and thus are inefficient. Furthermore, all protocols are designed to solve the basic millionaires’ problem, that is, to privately determine which of two natural numbers is greater. If the numbers are real, existing solutions do not directly work. These features limit the extensive application of the existing protocols. This study introduces and refines the first symmetric cryptographic protocol for the basic millionaires’ problem, and then extends the symmetric cryptographic protocol to privately determining which of two real numbers is greater, which are called the extended millionaires’ problem, and proposes corresponding protocols. We further prove, by a well accepted simulation paradigm, that these protocols are private. Constructed based on symmetric cryptography, these protocols are very efficient.

On F5 Steganography in Images

Steganalysis is the reasonable method to detect whether the transmitted media content contains secret messages (e.g. business secrecy). This paper proposes two steganalysis methods to estimate the modification ratio of F5 steganography and its improved version that are popularly used to hide secrecy in images. The proposed methods measure the distance between the coefficient histogram of a given image and that of an estimated stego image. The distance is measured based on relative entropy that has the superiority of measuring the distance between two distributions. The estimated modification ratio can be used to distinguish the stego images marked by F5 steganography or its improved version from the original images. Experimental results are given to show that the proposed methods outperform the existing quantitative steganalysis methods against F5 steganography and its improved version.

Weighted Stego-Image Steganalysis of Messages Hidden into Each Bit Plane

For hiding messages into multiple least significant bit (MLSB) planes, a new weighted stego-image (WS) steganalysis method is proposed to estimate the ratio of messages hidden into each bit plane. First, a new WS with multiple weights is constructed, and it is proved that when the squared Euclidean distance between the WS and the cover image is minimal, the weight parameters are equal to the embedding ratios in MLSB planes. Afterward, based on this result and an estimation of cover image, a simple estimation equation is derived to estimate the embedding ratio in each bit plane. Experimental results show that the new steganalysis method performs more stably with the change of embedding ratios than typical structural steganalysis, and outperforms the typical structural steganalysis method on the estimation accuracy when the embedding ratio in any bit plane is larger than 0.4.

A transcoding-resistant video watermarking algorithm based on corners and singular value decomposition

The singular value decomposition (SVD) mathematical technique provides an elegant method for extracting algebraic features form an image. When a small change is added to singular values, great variance of image doesn’t occur, and singular values in an image are less affected if general image processing is performed. Because singular value matrix of an image has good stability, the watermark can be embedded to this matrix without causing large variation in the stego-image. The reason of causing block effects and flicker in the traditional watermarked video using SVD is firstly analyzed in this paper. Based on the feature of SVD and that human eyes are not sensitive to the changes in corner area of each frame of video, we embed watermark into blocks with corner inside using quantization index modulation. We analyze the validity of the proposed algorithm about synchronizing error, block effects, and flicker. The experiment shows that the proposed approach has an excellent robustness against transcoding and some normal attacks, such as adding noise, re-encoding and so on without causing any block effects and flicker. The result also shows that the correct rate of extracting watermark can achieve 98xa0% per second.