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Jin S.,Chinese Academy of Sciences | Yang Z.,Information Engineering University | Cui X.,Chinese Academy of Sciences
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

The detection of covert channels in an information flow model is a practical problem in determining whether the security guarantees of the operation system have been achieved. Asbestos system is a typical information confidentiality protection system. This poster introduces a formal approach to automatically detect covert channels in Asbestos systems. The approach innovatively generalizes a CSP (Communicating Sequential Process) based formal description of Asbestos system and utilizes Ray's noninterference Equivalence in the detection of covert channels. The covert channels are automatically detected by employing a CSP based model checking tool FDR2. © 2012 Springer-Verlag. Source

Pu Q.,Tongji University | Pu Q.,Information Engineering University | Wu S.,China Institute of Technology
International Arab Journal of Information Technology | Year: 2012

The Session Initiation Protocol (SIP) is commonly used to establish Voice over IP (VoIP) calls. Mostly recently, Yoon et al. proposed a new secure and efficient SIP authentication scheme in a converged VoIP network based on ECC. In this paper, we first demonstrate that the recently proposed SIP authentication scheme is insecure against off-line password guessing attacks. Thereafter, we propose an enhanced SIP authentication scheme that enjoys provable security. And yet our scheme is simple and efficient. Therefore, the end result is more suited to be a candidate for SIP authentication scheme. Source

Zheng K.,Information Engineering University | Ruan R.,Xian Research Institute of Surveying and Mapping | Jia X.,Xian Research Institute of Surveying and Mapping | Lu H.,Tech Data
Lecture Notes in Electrical Engineering | Year: 2016

The implementation of precise point positioning ambiguity fixing depends on the products which can be used to recover the characteristics of ambiguity by the service side. When users need to implement single difference between satellite method and the decoupled clock method they have no way to achieve the products, so they must provide the products themselves hard, but when users need to implement the integer phase clock method they can use the wide-lane FCB and integer phase clock provided by CNES. Therefore, in this paper we put forward the algorithm of sequential ambiguity fixing with direct rounding and analyze the effects of ambiguity fixing kinematic PPP based on this method. First we analyze the principle of PPP ambiguity fixing based on the models, and then we introduce the algorithm and how the users have to implement integer phase clock method. Last, based on the principle analysis we design the single-day and two-hour dynamic experiments, which are simulated by static data. Results of numerous stations show that: the algorithm of sequential ambiguity fixing with direct rounding can significantly improve the accuracy of positioning and the east shows more obvious effects, the improvement proportion of single-day and two-hour were approximately 30 and 60%, so the result can verify the validity of the method proposed. © Springer Science+Business Media Singapore 2016. Source

Yuan L.,Information Engineering University | Wang H.,National University of Defense Technology | Yin G.,National University of Defense Technology | Shi D.,National University of Defense Technology | Zhu Y.,National University of Defense Technology
International Journal of Advancements in Computing Technology | Year: 2011

Open Source Software (OSS) evaluation uses various metrics to compute the scores or levels of OSS. However the metrics used in existing evaluation models are difficult to rate and costly to obtain, and the rates of metrics are often tendentiously subjective and inconvincible. This paper tries to find some kinds of data in OSS repositories which can be easily obtained and used as metrics for more practical OSS evaluation. By mining and analyzing nearly 8,000 SourceForge projects, this paper achieves three interesting observations: (1) The Pearson correlation coefficients between the role number and the rank of projects are surprisingly high which means they are strongly related; (2) the centralities of roles reveal a irradiative deduction that the projects with higher rank usually tend to have more rational and balanced role structure; (3) the centralities and correlation of roles provide valuable clues for constructing a reference role structure model. These results show that the role structure in OSS projects has a great influence on their quality and provide a new dimension of metrics for more automatic and practical OSS evaluation. Source

Chen L.,National Digital Switching System Engineering Technical Researching Center | Tang H.,National Digital Switching System Engineering Technical Researching Center | Wang J.,Information Engineering University
Proceedings of the 2013 International Conference on Intelligent Control and Information Processing, ICICIP 2013 | Year: 2013

VANET is new kind of Ad hoc. It is widely used in ITS (Intelligent Transportation Systems), which has many characteristics as large scale network, fast moving nodes, the frequently changing topological structure and easily divided networks. Therefore, routing protocol design must fully consider of this characteristics with much node information that bring a great challenge to the security of VANET. In this paper, we divide the information type into four categories based on different content, and analyze the security threats in different information type, then summarize the existing security technologies and give the possible research directions. © 2013 IEEE. Source

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