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1.
Chu Chao-Hsien 《东南大学学报》2008,(Z1)
To address security and privacy issues in radio frequency identification (RFID) traceability networks, a multi-layer privacy and security framework is proposed, which includes four facets: a security model, a communication protocol, access permission and privacy preservation. According to the security requirements that are needed in an RFID system, a security model that incorporates security requirements that include privacy of tag data, privacy of ownership, and availability of tag identity is introduced. Using this model, a secure communication protocol that can be used for anti-counterfeiting, automatic identification and privacy preservation is then developed. In order to manage the number of parties, data records of items, and complicated transitions of access permissions in an item-level traceability context, a well-designed access control protocol is proposed to parties that can prove the physical possession of an item;meanwhile, to address the privacy issues during data sharing in an RFID network, a vision of database systems that take responsibility for the privacy of the data they manage is also presented. 相似文献
2.
In this paper, the security technology of ad hoc networks is studied.To improve the previous multi-receiver signcryption schemes, an ID-based multi-message and multi-receiver signcryption scheme for rekeying in ad hoc networks is proposed.In this scheme, a sender can simultaneously signcrypt n messeges for n receivers, and a receiver can unsigncrypt the ciphertext to get his message with his own private key.An analysis of this scheme indicates that it achieves authenticity and confidentiality in the random oracle model while being of lower computation and communication overhead.Finally, for the application of our scheme in ad hoc, a threshold key updating protocol for ad hoc networks is given. 相似文献
3.
The flooding distance is an important parameter in the design and evaluation of a routing protocol,which is related not only to the delay time in the route discovery,but also to the stability and reliability of the route.In this paper, the average flooding distance (AFD) for a mobile ad hoc network (MANET) in a random graph model was given based on the dynamic source routing (DSR) protocol.The influence of spatial reuse on the AFD was also studied.Compared with that in the model without the spatial reuse,the AFD in the model with the spatial reuse has much smaller value,when the connetivity probability between nodes in the network is small and when the number of reused times is large.This means that the route discovery with the spatial reuse is much more effective. 相似文献
4.
There is general agreement today that the communicative approach to the teaching and learning of English is the correct one and that we learn English for the purpose of communicating with other English-speakers. However, this is a comparatively recent development. This paper begins with an historical overview outlining the origins of the communicative approach in Europe and the United States and noting that they arrived at a consensus for entirely different historical reasons. In China English replaced Russian as the most important foreign language a generation ago but even then the emphasis was on receptive skills. The thorny question of authenticity is then discussed. While everyone agrees that in theory authenticity is a key consideration there is considerably less agreement on how to convert theory into practice. Finally the paper goes on to note how recent practice has abandoned the teacher-centered approach in favor of the learner-centered approach and the exercise-based approach in favor of the task-based approach, The task-based approach emphasizes integrated as opposed to individual skills acquisition. Examples of integrated tasks are given in the Appendix. 相似文献
5.
Suriamurthee Moonsamy Maistry Jugathambal Ramdhani 《美中教育评论》2010,7(4):23-29
Entrepreneurship education in the South Africa is often presented as a neutral discipline. Yet fundamental to any entrepreneurship education program should be the integration of key issues, such as ethics, values and social responsibility. This paper reports on a study that set out to explore student teachers experiences of engaging in an entrepreneurship education program specially enhanced to create an awareness of the link between entrepreneurship and social responsibility. It argues that exposure to a program of this nature is a powerful means to dispel the myth that entrepreneurship is a neutral discipline and that such exposure creates useful avenues for student teachers to examine their own constructions and perceptions of entrepreneurship and social responsibility. This paper draws on data constructed in a qualitative research project that engaged the tenets of symbolic interactionism in order to understand how students experienced the program and to understand their changing perceptions. 相似文献
6.
杨正瓴 《天津大学学报(英文版)》2011,17(6):446-449
The more unambiguous statement of the P versus NP problem and the judgement of its hardness, are the key ways to find the full proof of the P versus NP problem. There are two sub-problems in the P versus NP problem. The first is the classifications of different mathematical problems (languages), and the second is the distinction between a non-deterministic Turing machine (NTM) and a deterministic Turing machine (DTM). The process of an NTM can be a power set of the corresponding DTM, which proves that the states of an NTM can be a power set of the corresponding DTM. If combining this viewpoint with Cantor’s theorem, it is shown that an NTM is not equipotent to a DTM. This means that "generating the power set P(A) of a set A" is a non-canonical example to support that P is not equal to NP. 相似文献
7.
SOZL (structured methodology object-oriented methodology Z language) is a language that attempts to integrate structured method, object-oriented method and formal method. The core of this language is predicate data flow diagram (PDFD). In order to eliminate the ambiguity of predicate data flow diagrams and their associated textual specifications, a formalization of the syntax and semantics of predicate data flow diagrams is necessary. In this paper we use Z notation to define an abstract syntax and the related structural constraints for the PDFD notation, and provide it with an axiomatic semantics based on the concept of data availability and functionality of predicate operation. Finally, an example is given to establish functionality consistent decomposition on hierarchical PDFD (HPDFD). 相似文献
8.
This paper studies the security of an image encryption scheme based on the Hill cipher （Ismail et al., 2006） and reports its following problems： （1） There is a simple necessary and sufficient condition that makes a number of secret keys invalid; （2） It is insensitive to the change of the secret key; （3） It is insensitive to the change of the plain-image; （4） It can be broken with only one known/chosen plaintext; （5） It has some other minor defects. The proposed cryptanalysis discourages any use of the scheme in practice. 相似文献
9.
The subject of this work is the assessment on the stability of an excavated high slope in order to insure the security of the building site adjacent to the slope,which is frequently encountered in town construction in mountainous areas due to terrain limit.On the base of some typical engineering cases in Chongqing,several crucial problems on security assessment of building site adjacent to an excavated high slope,including the natural geological conditions and man-destroyed degree,engineering environment,potential failure pattern of the high slope,calculation parameters and analysis methods,are roundly discussed.It is demonstrated that the conclusion of security assessment can be determined according to the aspects above-mentioned,and the security assessment is one of the fundamental data to insure the safety of the related construction,site and buildings. 相似文献
10.
Most of the proposed concurrency control protocols for real-time database systems are based on serializability theorem.Owing to the unique characteristics of real-time database applications and the importance of satisfying the timing constraints of transactions,serializability is too strong as a correctness criterion and not suitable for real-time databases in most cases.On the other hand,relaxed serializability including epsilon-serializability and similarity-serializability can allow more real-time transactions to satisfy their timing constraints,but database consistency may be sacrificed to some extent.We thus propose the use of weak serializability(WSR)that is more relaxed than conflicting serializability while database consistency is maintained.In this paper,we first formally define the new notion of correctness called weak serializability.After the necessary and sufficient conditions for weak serializability are shown,corresponding concurrency control protocol WDHP(weak serializable distributed high prority protocol)is outlined for distributed real time databases,where a new lock mode called mask lock mode is proposed for simplifying the condition of global consistency.Finally,through a series of simulation studies,it is shown that using the new concurrency control protocol the performance of distributed realtime databases can be greatly improved. 相似文献
11.
介绍了IPsec的基本组成和一组IKE协议.分析了IKE协议的安全特性,以及IKE的协商过程.其中包括:在主模式中建立ISAKMP SA的过程和在快速模式中利用已建立好的ISAKMP SA完成IPsec SA的协商.通过详细分析主模式中用于完成SA要交换的六个消息的发送步骤、属性、结构来说明安全性的实现. 相似文献
12.
IKE协议中存在的安全漏洞 总被引：1，自引：0，他引：1
IKE(Internet key exchange)协议是IPSec协议中缺省的密钥管理协议，但是它的实现上却相当复杂，所以可能出现安全漏洞．本主要分析了IKE可能出现的一种安个漏洞． 相似文献
13.
张爱科 《柳州职业技术学院学报》2006,6(3):81-84
本文首先介绍了IPSec下现有密钥交换协议IKE,以及新一代密钥交换规范IKEv2,尤其是他们的协商原理。针对IKE在性能和安全方面的缺陷,分析比较了IKEv2在密钥交换的安全性和高效性上所做出的改进。为构建VPN网络等应用场合,指明了密钥交换协议的选取依据。 相似文献
14.
IKE协议及安全性分析 总被引：1，自引：0，他引：1
因特网密钥交换协议IKE(Intemet Key Exchange)是一种混和密钥协议，它用于密钥的协商、交换和认证。在分析IKE协议工作原理的基础上，对可能遭受的拒绝服务攻击和中间人攻击做了进一步的探讨。最后对IKE的进一步研究提出了看法。 相似文献
15.
基于DH困难问题,提出一种基于身份的两方密钥交换协议,并对协议的安全性进行了分析。所提出的协议中,会话密钥的生成需要参与方的长期私钥和选取的随机数。安全性分析表明,所提出的协议能满足两方密钥交换协议的安全性要求。 相似文献
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17.
利用双线性对理论,提出一种两方密钥交换协议,并对协议的安全性进行了简单分析。所提出的协议中,用户的公钥利用其身份信息计算,而用户的私钥有私钥生成中心生成,会话密钥由双线性对知识计算出。分析表明,所提出的协议是安全的。 相似文献
18.
INTRODUCTION Wireless communications is advancing rapidly in recent years. After 2G (e.g. GSM) widely deployed in the world, 3G mobile communication systems are spreading step by step in many areas. At present, some countries have already launched investigations beyond 3G (B3G) and 4G. Along with the wireless communications’ rapid development, the secure ac-cess authentication of the users within wireless net-works is becoming very critical, and so, more and more attention is focused… 相似文献
19.
针对EPC物联网中数据安全性问题,以及传统的PKI系统构建开销过大、认证体系复杂等问题,提出一种轻型的PKI加密算法.该算法结合EPC物联网的特点,通过引入EPC密钥和基于社会学信任协商模型的认证机制,对传统的PKI进行裁减,在不改变传统PKI基本功能的前提下对加密算法及CA管理进行简化,形成了轻型的PKI算法,构建了具有复合物联网特点的安全体系结构.实验表明：改进的算法有效地实现了对EPC数据访问的控制,保证了物联网中的信息传输效率. 相似文献