Structural robustness of city road networks based on community

Road network robustness is the ability of a road network to operate correctly under a wide range of attacks. A structural robustness analysis can describe the survivability of a city road network that is under attack and can help improve functions such as urban planning and emergency response. In this paper, a novel approach is presented to quantitatively evaluate road network robustness based on the community structure derived from a city road network, in which communities refer to those densely connected subsets of nodes that are sparsely linked to the remaining network. First, a road network is reconstructed into a set of connected communities. Then, successive simulated attacks are conducted on the reconstructed road networks to test the performance of the networks under attack. The performance of the networks is represented by efficiency and the occurrence of fragmentation. Three attack strategies, including a random attack and two intentional attacks, are performed to evaluate the survivability of the road network under different situations. Contrary to the traditional road segment-based approach, the community-based robustness analysis on a city road network shows distinct structural diversity between communities, providing greater insight into network vulnerability under intentional attacks. Six typical city road networks on three different continents are used to demonstrate the proposed approach. The evaluation results reveal an important feature of the structure of city road networks from a community-based perspective, i.e., that the structure is robust under random failure but fragile under intentional attack. This result is highly consistent in different city road network forms.     

Modern breaking of Enigma ciphertexts

“Breaking German Army Ciphers” is the title of a Cryptologia article from 2005, describing the lucky survival of several hundred authentic Enigma messages of World War II, and an account of a ciphertext-only cryptanalysis of a large number of these messages, leaving only a few (mostly short messages) unbroken. After reviewing the work done, and investigating the reasons for both lucky breaks and close misses, the modern ciphertext-only attack on Enigma messages is improved, especially on genuine ones with short lengths and/or many garbles. The difficulties of a proper measure for the candidate’s closeness to a plaintext are clarified. The influence on the decryption process of an empty plugboard and one with only a few correct plugs is examined. The method is extended by a partial exhaustion of the plugboard combined with an optimized hillclimbing strategy. The newly designed software succeeds in breaking formerly unbroken messages.     

Effect of fine crack width and water cement ratio of SHCC on chloride ingress and rebar corrosion

SHCC (Strain Hardening Cement-based Composite) is a material known for its strain-hardening behavior under tensile and bending stress and its characteristic numerous small cracks. SHCC is expected to show superior durability because of the fineness of the cracks. In this study, chloride ingress through cracks into SHCC and progress of rebar corrosion in three mixtures of SHCC with various water-cement ratios were investigated. Through a chloride solution immersion test, it was confirmed that chloride could penetrate through even very fine cracks. The resistivity of cracked SHCC against chloride ingress is mainly governed by the accumulated crack width and the water cement ratio. Chloride pre-mixed SHCC specimens were left in a high-temperature, high-humidity chamber for 11 months to promote rebar corrosion. While the accumulated crack width and the water cement ratio were both influential to an increase in corrosion area, only the water cement ratio had bearing on corrosion loss.     

Research on HTML5 application cache poison attack

HTML5 application cache (AppCache) allowed Web browser to access Web offline.But it also brought a new method of cache poisoning attack that was more persisting.As for websites which used the AppCache,a novel poisoning method RFTM (replace file twice method),in which the attacker replaced the manifest file twice to poison the client’s AppCache,was proposed.Compared with the original attack,the legal server would not receive abnormal HTTP requests from the client in the attack.Therefore,changing the server configuration could not prevent the client from the RFTM AppCache poisoning.To avoid the attack mentioned above,a lightweight signature defense scheme Sec-Cache in application layer was designed.Furthermore,experiments show that it has good performance and compatibility.     

ECC fault attack algorithm based on Grover's quantum search algorithm with 0.1π phase rotation

The Grover's a1gorithm was used for fau1t attack against the pub1ic key cryptography.A fixed phase rotation based Grover's a1gorithm was proposed，and the probabi1ity of success achieved 99.23% with 0.1π phase rotation.Combined with the fau1t attack further，ECC（e11iptic curve cryptography）vo1tage burr attack a1gorithm based on Grover a1gorithm with 0.1π phase rotation was proposed.Then a safety Kob1itz curve，K-163，pub1ished successfu11y attacked by NIST on binary domain in simu1ation and the success rate was 100%.The comp1exity of the attack great1y reduces on the exponentia1.It was a new effective way，except the Shor's a1gorithm，to attack pub1ic key cryptography by quantum computing，and it contributed to extend the attack ways to the other pub1ic key cryptography.     

非点对点消息网间互联互通技术方案

介绍了我国开放非点对点消息网间互联互通的背景,并分阶段对我国实现非点对点消息网间互联互通的技术方案进行了介绍和分析。     

Evaluating Intrusion‐Tolerant Certification Authority Systems

Various intrusion‐tolerant certification authority (CA) systems have been proposed to provide attack resilient certificate signing (or update) services. However, it is difficult to compare them against each other directly, due to the diversity in system organizations, threshold signature schemes, protocols and usage scenarios. We present a framework for intrusion‐tolerant CA system evaluation, which consists of three components, namely, an intrusion‐tolerant CA model, a threat model and a metric for comparative evaluation. The evaluation framework covers system organizations, protocols, usage scenarios, the period of certificate validity, the revocation rate and the mean time to recovery. Based on the framework, four representative systems are evaluated and compared in three typical usage scenarios, producing reasonable and insightful results. The interdependence between usage scenarios and system characteristics is investigated, providing a guideline to design better systems for different usage scenarios. The proposed framework provides an effective and practicable method to evaluate intrusion‐tolerant CA systems quantitatively, and helps customers to choose and configure an intrusion‐tolerant CA system. Moreover, the comparison results offer valuable insights to further improve the attack resilience of intrusion‐tolerant CA systems. Copyright © 2011 John Wiley & Sons, Ltd.     

风致静力扭角对桥梁颤振性能影响的节段模型试验研究

自由振动试验识别得到的气动参数已包含了一定的、但与实桥不严格相似的风致静力扭角的影响.为了在颤振分析中能精确考虑风致静力扭角的影响,首先必须消除节段模型试验中风致静力扭角对气动导数识别结果的影响.通过在试验过程中使节段模型作受控反向旋转可以消除平均风附加攻角,然后以象山港大桥为背景,将消除平均风附加攻角后的试验结果与常规试验结果相比较,对风致静力扭角对节段模型系统的阻尼比、气动导数和临界风速的影响进行了初步讨论.研究结果表明:风致静力扭角对模型扭转阻尼比和与扭转有关的气动导数有明显的影响.象山港大桥节段模型在+3°攻角发生颤振时风致静力扭角约为0.32°,攻角修正以后节段模型颤振临界风速识别结果提高了7%.     

物联网射频识别技术的安全问题及防范策略

物联网射频识别技术是利用无线射频方式进行非接触双向通信,自动识别目标对象并获取相关数据的高新技术,广泛应用于门禁系统、车辆防盗、物流管理等安全防范领域中。本文在简要介绍射频识别系统的工作原理和应用的基础上,针对射频识别系统面临的安全问题,提出相应的防范策略,以促进射频识别技术的健康发展。     

商品包装的视觉流程设计及应用

对商品包装的视觉流程的认知过程以及消费者在购买商品时的视觉心理进行了分析,归纳了商品包装视觉流程设计要充分运用视觉中心、视觉惯性和视觉特性的三大原则;解析了色彩、图形、文字三大基本要素在商品包装视觉流程设计中的应用,最终实现商品包装设计完全符合消费者视觉心理、符合商品的内涵特质及功能需求、符合时代审美变化的目的。