Since it's hard to analyze the cryptographic procedure using method of property scan or debugging for the variety and different implementation of cryptographic algorithms, a method was proposed based on library function prototype analysis and their calling-graph building. Library functions prototype analysis is analyzing cryptographic algorithm knowledge and library frame knowledge to form a knowledge base. Calling-graph building is building a calling-graph that reflects the function calling order according to parameter value of the functions. Finally cryptographic algorithm knowledge and library frame knowledge on the calling-graph were extracted. The method discriminated common cryptographic algorithm almost 100%, and it could not only recover cryptographic data, key and cryptographic mode, but also help to analyze the relationship between more than two cryptographic algorithms dealing with the same data. The method could be used to analyze Trojan, worm and test whether the library is used correctly.
To solve the defect of traditional network traffic prediction forecasting, and obtain good forecasting results of network traffic, a network traffic forecasting model based on Gaussian Process Regression (GPR) was proposed. Firstly, the time delay and embedding dimension of network traffic were calculated to construct the learning samples of GPR, and then training samples were input to Gaussian process to learn in which Invasive Weed Optimization (IWO) algorithm was used to optimize the parameters of Gaussian process, and finally, the forecasting model of network traffic was established based on the optimal parameters, and the performance was tested by network traffic data. The results show that the proposed model can improve the forecasting precision of network traffic and it has great practical application value.
The modified coding algorithm based on listless zerotree wavelet was proposed by studying SPIHT and LZC. The zerotree coding process was improved, and the complexity of the encoding procedure was reduced. The novel algorithm was easy to be realized by hardware. The top bits of transformed coefficients were used to store flag maps, and the memory requirements of coding process were further reduced. Experiment results show that PSNR(Peak Signal Noise Ratio) values of the novel algorithm are obviously better than those of LZC, and less than those of SPIHT appreciably at the same compression ratio.
The document images scanned may be skew somehow. Severe image skew makes image segmentation difficult and lowers character recognition accuracy. A new approach of skew detection based on Hough transform was presented. In order to overcome the heavy computing burdens of Hough transform,the method selected the subfield with part representation and extracted the horizontal edge from images in the first place, then performed two-stage Hough transform on the edge extracted. Experiment results show that it corrects the skew document images more rapidly and accurately than general Hough method and cross relation method.
In this paper such a general architecture was presented based on Rejaie’s work on the architecture of media streaming servers, which took into consideration the functions and characteristics of live streaming servers, and incorporated the impacts of fluctuant network environment on them. In this architecture, four function modules, namely Rate Control Module, Error Control Module, Video Quality Adaptation Module and Buffer Control Module, comprise the whole server. These modules respectively perform specific tasks, and collaborate to enable the whole server systems to provide adaptive video streaming services as a whole. How they can interplay and cooperate was discussed thoroughly in this paper. This architecture presented in the paper can be flexibly configured according to specific needs of particular applications, and can be helpful to development of live streaming server systems.