Xinxin Niu

A color image watermarking algorithm resistant to print-scan

Print-scan resilient data hiding finds important applications in image copyright protection. This paper proposes a novel algorithm which combines the methods of image complexity and discrete Fourier transform (DFT). Based on appropriate block partition, we can compute the local image complexity of the block, which is determined whether to embed watermark in this block. The red component of the block is transformed with DFT and a watermark is embedded in the mid-frequency of DFT coefficients. The hidden data can be extracted without using the original image to verify the copyright of the reproduced image. Experiment results suggest that the proposed method is robust after high-quality printing and scanning.

A Semi-supervised Ensemble Approach for Mining Data Streams

There are many challenges in mining data streams, such as infinite length, evolving nature and lack of labeled instances. Accordingly, a semi-supervised ensemble approach for mining data streams is presented in this paper. Data streams are divided into data chunks to deal with the infinite length. An ensemble classification model E is trained with existing labeled data chunks and decision boundary is constructed using E for detecting novel classes. New labeled data chunks are used to update E while unlabeled ones are used to construct unsupervised models. Classes are predicted by a semi-supervised model Ex which is consist of E and unsupervised models in a maximization consensus manner, so better performance can be achieved by using the constraints from unsupervised models with limited labeled instances. Experiments with different datasets demonstrate that our method outperforms conventional methods in mining data streams.

Empirical analysis of software coupling networks in object-oriented software systems

The increasing scale and complexity of software systems have led to a large amount of work being performed in the area of software architecture of object-oriented systems. For the purpose of reasonable description of software structure, we make use of complex network theory to characterize and describe their macroscopic properties. We propose a directed software coupling network, and then empirical analysis of four open source software is implemented. We summarize the general statistical features of software coupling network, and find that software coupling network is of small-world and scale-free property, the exponents of in-degree and out-degree distributions are different, and the betweenness distribution of SCN is also power law. Furthermore, we analyzed the causes of behaviors software coupling network possessed.

Dynamic Data Flow Graph-based software watermarking

In this paper we indicate the concept of Dynamic Data Flow Graph based on the dynamic data dependency during execution of software. On this basis, we propose a dynamic software watermarking algorithm, which embeds watermarking information into DDFG of software, and discuss the implementation of embedding and extracting watermark. Finally we analyze the performance of this algorithm.

A novel model for query over encrypted XML databases

In recent years, there has been increasing concern about “Database as a Service”(DAS) architectures. Data security is the overriding concern in DAS, and encryption is a natural solution. However, queries over encrypted databases are usually inefficient due to a heap of time on the encryption and decryption. In this paper, we present an encryption scheme and XQuery translation model of XML database. The major work and contribution of this paper are as below: 1) Splitting method is proposed in the encryption scheme, in which more flexible encryption granularity is obtained. 2) We put forward the encryption strategy that, by encrypting two or more fragments together, is efficient to resist various kinds of database attack owing to the changed ciphertext distribution and data size by splitting. 3) An XQuery translation model is introduced, by converting the query of XML data into that of relational data, combined with XML Schemas Compression and hash technology, which perform the XQuery language efficiently. Our experimental evaluation shows that our XML database encryption and query model achieves both excellent query efficiency and robust security.

A correlation analysis method of network security events based on rough set theory

Network security event correlation can find real threat through correlating security events and logs generated by different security devices and can be aware of the network security situation accurately. This paper propose a network security events correlation scheme based on rough set, build database of network security events and knowledge base, gives rule generation method and rule matcher. This method solves the simplification and correlation of massive security events through combining data discretization, attribute reduction, value reduction and rule generation.

Runtime protecting system for java applications with dynamic data flow analyzing

With the rapidly development of the computer and internet technology, the security problem of software is more and more concerned. In this paper we present a runtime protecting system for java applications with dynamic data flow analyzing. We proposed the runtime software protecting algorithm and discussed the design and implementation of the runtime protecting system for java applications. At last, we compared runtime protecting system with static code analysis and analyze the performance of our implementation.

A new credential routing model based on trust theory

Router has acted as more and more important role in the large-scale network. In the meantime, the security of the router become more seriously. In this paper, we propose a new algorithm to decide a credential routing path from the start router to the end one based on the trust theory that considers the trustworthy of link, the cost of link and the trustworthy of router as the critical factors so as to utilize the principle of the grey correlation degree to obtain a credential routing path, instead of weighted mean in existed methods of trust measurement. We guarantee that packet can secure transfer under the credential routing path and identify the remote routers that are subject to attacks.

A real-time information hiding algorithm based on HTTP protocol

Based on the structure of HTTP protocol, a real-time information hiding algorithm was proposed in this paper, to solve the problem that embedding a mass of data in the TCP/IP packet. The secret information is embedded in HTTP protocol header fields. Its proved that the capacity of the algorithm is perfect by experiments, and more than 1000 bytes of data could be embedded in a HTTP request-packet (Get-packet), while the transparency is very well. At the same time, the information hidden will not affect on packets transmitting.