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结合具体物体打击事故,分析了研究脚手架、预留洞口和拆除落物打击安全事故发生的根本原因,总结脚手架、预留洞口和拆除落物打击事故的经验教训,指出应不断加强施工人员的安全教育培训,切实提高建筑从业人员的安全意识,以减少或避免施工过程中物体打击事故的发生。 相似文献
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一种基于SIFT的图像哈希算法 总被引:6,自引:1,他引:5
图像哈希是近年来颇受关注的一个研究热点,但现有的图像哈希算法普遍存在对几何攻击(主要包括尺度、旋转、剪切)鲁棒性不足的缺点,不能满足很多实际应用的需要.针对上述问题,提出了对几何攻击具有强鲁棒性的SIH图像哈希算法.本算法基于在图像匹配等领域得到广泛应用的SIFT算子,通过对SIFT特征向量进行有针对性的筛选和压缩、基于特征向量分布质心的量化生成图像摘要.为适应图像摘要构造的特性,设计了基于广义集合距的匹配算法来衡量图像摘要间的距离.在公开图像库上的实验结果表明,本算法对几何攻击和非几何攻击的鲁棒性均优于对比算法,可广泛服务于图像识别/认证类型的应用. 相似文献
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Mohammad Sabzinejad Farash SK Hafizul Islam Mohammad S. Obaidat 《Concurrency and Computation》2015,27(17):4897-4913
Password‐based two‐party authenticated key exchange (2PAKE) protocol enables two or more entities, who only share a low‐entropy password between them, to authenticate each other and establish a high‐entropy secret session key. Recently, Zheng et al. proposed a password‐based 2PAKE protocol based on bilinear pairings and claimed that their protocol is secure against the known security attacks. However, in this paper, we indicate that the protocol of Zheng et al. is insecure against the off‐line password guessing attack, which is a serious threat to such protocols. Consequently, we show that an attacker who obtained the users' password by applying the off‐line password guessing attack can easily obtain the secret session key. In addition, the protocol of Zheng et al. does not provide the forward secrecy of the session key. As a remedy, we also improve the protocol of Zheng et al. and prove the security of our enhanced protocol in the random oracle model. The simulation result shows that the execution time of our 2PAKE protocol is less compared with other existing protocols. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Steganalysis attack is to statistically estimate the embedded watermark in the watermarked multimedia,and the estimated watermark may be destroyed by the attacker.The existing methods of false negative probability,however,do not consider the influence of steganalysis attack.This paper proposed the game theory based false negative probability to estimate the impacts of steganalysis attack,as well as unintentional attack.Specifically,game theory was used to model the collision between the embedment and steganalysis attack,and derive the optimal building embedding/attacking strategy.Such optimal playing strategies devote to calculating the attacker destructed watermark,used for calculation of the game theory based false negative probability.The experimental results show that watermark detection reliability measured using our proposed method,in comparison,can better reflect the real scenario in which the embedded watermark undergoes unintentional attack and the attacker using steganalysis attack.This paper provides a foundation for investigating countermeasures of digital watermarking community against steganalysis attack. 相似文献
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研究了网络编码中的防窃听问题,在实际的网络编码环境中,敌人通常拥有完整的窃听能力。提出一种新颖的防全局窃听者的编码算法,利用r个映射值来随机化原始数据包,这表明每个数据包只需要一个被加密的符号,对于中间节点没有其他附加的要求。与其他的方法相比,本方法的效率更高,并且计算复杂度也适中。 相似文献
80.
RSA signature algorithms using the Chinese remainder theorem (CRT‐RSA) are approximately four‐times faster than straightforward implementations of an RSA cryptosystem. However, the CRT‐RSA is known to be vulnerable to fault attacks; even one execution of the algorithm is sufficient to reveal the secret keys. Over the past few years, several countermeasures against CRT‐RSA fault attacks have tended to involve additional exponentiations or inversions, and in most cases, they are also vulnerable to new variants of fault attacks. In this paper, we review how Shamir's countermeasure can be broken by fault attacks and improve the countermeasure to prevent future fault attacks, with the added benefit of low additional costs. In our experiment, we use the side‐channel analysis resistance framework system, a fault injection testing and verification system, which enables us to inject a fault into the right position, even to within 1 μs. We also explain how to find the exact timing of the target operation using an Atmega128 software board. 相似文献