We first discusses some threats to VoIP system and H. 323 architectures designed for VoIP communications on security point of view. Continues with presenting security requirements of VoIP, and explaining the essential...We first discusses some threats to VoIP system and H. 323 architectures designed for VoIP communications on security point of view. Continues with presenting security requirements of VoIP, and explaining the essential security constraints surrounding a seccessful VoIP deployment. Finally, suggests some strategies to implement the security and encryption functions of VoIP system based on H. 323. Key words VoIP - security - H. 323 protocol CLC number TP 393 Foundation item: Support by the National Natural Science Foundation of China (90104002)Biography: HUANG Yong-feng (1967-), male, postdoctoral fellow, research direction: multimedia communication based on IP protol.展开更多
In order to establish the sufficient and necessary condition that arbitrarily reliable systems can not be constructed with function elements under interference sources, it is very important to expand set of interferen...In order to establish the sufficient and necessary condition that arbitrarily reliable systems can not be constructed with function elements under interference sources, it is very important to expand set of interference sources with the above property. In this paper, the models of two types of interference sources are raised respectively: interference source possessing real input vectors and constant reliable interference source. We study the reliability of the systems effected by the interference sources, and the lower bound of the reliability is presented. The results show that it is impossible that arbitrarily reliable systems can not be constructed with the elements effected by above interference sources.展开更多
Interaction of antiworms with a worm population of e.g. hosts of worm infected and hosts of antiworm infected must be considered as a dynamic process. This study is an attempt for the first time to understand how intr...Interaction of antiworms with a worm population of e.g. hosts of worm infected and hosts of antiworm infected must be considered as a dynamic process. This study is an attempt for the first time to understand how introduction of antiworm affects the dynamic of network worm propagation. In this paper, we create a mathematical model (SIAR model) using ordinary differential equations to describe the interaction of worms and antiworms. Although idealized, the model demonstrates how the combination of a few proposed nonlinear interaction rules between antiworms and worms is able to generate a considerable variety of different kinds of responses. Taking the Blaster and Nachi worms as an example, we give a brief analysis for designing a practical antiworm system. To the best of our knowledge, there is no model for the spread of an antiworm that employs the passive scan and the finite lifetime and we believe that this is the first attempt on understanding the interaction between worms and antiworms.展开更多
文摘We first discusses some threats to VoIP system and H. 323 architectures designed for VoIP communications on security point of view. Continues with presenting security requirements of VoIP, and explaining the essential security constraints surrounding a seccessful VoIP deployment. Finally, suggests some strategies to implement the security and encryption functions of VoIP system based on H. 323. Key words VoIP - security - H. 323 protocol CLC number TP 393 Foundation item: Support by the National Natural Science Foundation of China (90104002)Biography: HUANG Yong-feng (1967-), male, postdoctoral fellow, research direction: multimedia communication based on IP protol.
基金Tsinghua University Research Foundation(JC2000025)
文摘In order to establish the sufficient and necessary condition that arbitrarily reliable systems can not be constructed with function elements under interference sources, it is very important to expand set of interference sources with the above property. In this paper, the models of two types of interference sources are raised respectively: interference source possessing real input vectors and constant reliable interference source. We study the reliability of the systems effected by the interference sources, and the lower bound of the reliability is presented. The results show that it is impossible that arbitrarily reliable systems can not be constructed with the elements effected by above interference sources.
基金supported in part by the National Natural Science Foundation of China(Grant No.60203004).
文摘Interaction of antiworms with a worm population of e.g. hosts of worm infected and hosts of antiworm infected must be considered as a dynamic process. This study is an attempt for the first time to understand how introduction of antiworm affects the dynamic of network worm propagation. In this paper, we create a mathematical model (SIAR model) using ordinary differential equations to describe the interaction of worms and antiworms. Although idealized, the model demonstrates how the combination of a few proposed nonlinear interaction rules between antiworms and worms is able to generate a considerable variety of different kinds of responses. Taking the Blaster and Nachi worms as an example, we give a brief analysis for designing a practical antiworm system. To the best of our knowledge, there is no model for the spread of an antiworm that employs the passive scan and the finite lifetime and we believe that this is the first attempt on understanding the interaction between worms and antiworms.
