一种新的轻量级RFID双向认证协议

RFID技术是一种广泛应用于各种物体识别和跟踪的自动识别技术,它适用于多个领域。然而,设计出一个安全的轻量级的RFID认证协议是一项具有挑战性的任务。最近Kulseng等人提出了一种轻量级RFID认证协议,该协议采用物理不可克隆技术和线性反馈移位寄存器来实现,非常适合轻量级操作。分析发现,该协议存在几个严重的安全问题。在分析上述协议的基础上,提出了一种新的轻量级RFID双向认证协议。分析表明,新协议在保持轻量级操作的同时,具有更好的安全性和保密性。     

基于Feistel结构的超轻量级分组密码算法(PFP)

面向无线终端资源受限环境对加密算法的应用需求,借鉴PRESENT算法的设计思想,采用Feistel结构,并修改扩散层的P置换,设计了一种超轻量级分组密码算法PFP。其硬件实现需要1355GE,优于PRESENT算法,满足资源极端受限环境的需求(2000GE以下)。速度测试结果表明,PFP算法的软件实现效率约为PRESENT算法的1.5倍。依赖性测试、线性分析、差分分析、不可能差分分析和密钥编排攻击表明,PFP算法满足轻量级分组密码的安全需求。     

目录服务技术及其在NOS中的应用

目录服务能构建更为安全有效,易于管理的网络应用于平台,该项技术已越来越受到业界的重视。本文首先介绍了目录服务的基本概念和它的协议基础,然后重点介绍了两 网络操作系统中的目录服务技术：Novell的NDS和Microsoft的AD,并分析了两者的异同。     

基于LDAP服务器的模式管理系统研究与设计

以一个电子政务研究中的基于LDAP服务器的模式管理研究为背景,通过对LDAP服务器的特性和所需安全功能的研究和分析,给出了以LDAP服务器为基础和以安全服务系统为数据交换平台的模式管理系统的开发设计方案,突破LDAP服务器自身提供的安全限制,同时也体现了目录和文件管理的便捷性。     

基于CIM的机群系统资源信息模型

通过对CIM进行面向机群系统的扩展和裁减,设计了一种基于CIM的机群系统资源信息模型,并且在Linux上用LDAP实现了这个信息模型,为表示机群系统的资源信息提供了一种统一的方式,为大规模机群系统的资源信息服务、高性能计算服务和其他相关应用打下了良好的基础。     

基于PUF的轻量级RFID安全认证协议

针对现有的RFID(Radio Frequency Identification)认证协议存在的安全隐私保护弱点以及成本过高问题,提出一个基于PUF(Physical Unclonable Functions)的轻量级RFID安全认证协议。利用PUF与LFSR(Linear Feedback Shift Register)实现阅读器和标签之间强的安全认证。另外,协议中增加了阅读器二次验证安全机制,为了保证阅读器与标签共享密钥同步,添加了不良攻击标识M等手段,解决了已有认证协议存在的多种安全漏洞。安全性分析表明该认证协议不仅成本低,而且能够有效地抵抗物理攻击、DoS攻击、同步破坏攻击等多种攻击,满足了认证协议的正确性、安全性、隐私性。     

Neapolitan Yellow Tuff as raw material for lightweight aggregates in lightweight structural concrete production

The possibility of using Italian zeolitized volcanoclastites for the production of lightweight aggregates in the building industry has been tested.The present paper definitely demonstrates the good attitude of the Neapolitan Yellow Tuff (NYT) for the production of lightweight expanded aggregates (LEA) with bulk densities ranging between 0.9 and 1.1 g/cm³. LEAs showing these features, usually manufactured with clays, are mainly used in the production of lightweight structural concretes (LSC). The physical characterization of LEAs was carried out by means of: grain size analysis, loose weight, mean density of the single grain, water absorption after 30 min and 24 h, and strength of particles (UNI-7549). Afterwards, LEAs were mixed with sand, cement and water to prepare cubic concrete blocks following the UNI specifications (UNI-7549-12). On these specimens, the unit weight and uniaxial compressive strength after 28 days were determined.The investigated parameters measured both on LEAs and concretes, are comparable with those measured on materials commonly traded in Italy.The obtained results foresee interesting potential applications of a raw material characterized by a low exploitation cost and a widespread availability on the Italian territory.     

Characterization of concrete properties from dielectric properties using ground penetrating radar

This paper presents the experimental results of a study of the relationships between light-weight (LWAC) and normal aggregate concrete (NAC) properties, as well as radar wave properties that are derived by using ground penetrating radar (GPR). The former (LWAC) refers to compressive strength, apparent porosity and saturated density, while the latter (NAC) refers to real part of dielectric permittivity (ε' or real permittivity) and wave energy level (E). Throughout the test period of the newly cast concrete cured for 90 days, the above mentioned material properties gradually changed which can be attributed to the effects of cement hydration, different types of aggregates and initial water to binder ratios. A number of plots describing various properties of concrete such as dielectric, strength and porosity perspectives were established. From these plots, we compare the characteristics of how much and how fast free water was turned to absorbed water in LWAC and NAC. The underlying mechanisms and a mechanistic model are then developed.     

Load-carrying capacity of lightly reinforced,prefabricated walls of lightweight aggregate concrete with open structure

The paper presents and evaluates the results of a coordinated testing of prefabricated, lightly reinforced walls of lightweight aggregate concrete with open structure. The coordinated testing covers all wall productions in Denmark and will therefore provide a representative assessment of the quality actually produced. Existing and new formulas for the capacity are evaluated by comparison to the test results and a new model with a good correlation with the test results is presented.     

Proportioning and characterization of lightweight concrete mixtures made with rigid polyurethane foam wastes

This paper presents the results of an experimental study concerning the incorporation of polyurethane (PUR) foam wastes into cementitious mixtures in order to produce lightweight concrete. A semi-empirical method is first proposed to predict the density of fresh PUR foam-based concrete mixtures. Seven concrete mixtures containing various PUR foam volume fractions (from 13.1% to 33.7%), and two reference concrete mixtures (without PUR foam) were prepared and characterized. In particular, their thermal and mechanical properties were determined. This permitted to quantify the influence of the PUR foam volume fraction on these parameters. Some specimens were maintained under water during 28 days, while the others were dried in air. The PUR-foam concrete thermal conductivity and compressive strength are, respectively, 2–7 times and 2–17 times lower than those of the reference mixture, depending on the volume fraction of PUR foam and on the curing conditions. Besides, the use of PUR foam in concrete implies a strong increase in the drying shrinkage and in the mass loss during the first seven days. These results can be related to the high porosity and the weak compressive strength of alveolar polyurethane.