可信执行环境软件侧信道攻击研究综述

为保护计算设备中安全敏感程序运行环境的安全,研究人员提出了可信执行环境(TEE)技术,通过对硬件和软件进行隔离为安全敏感程序提供一个与通用计算环境隔离的安全运行环境.侧信道攻击从传统的需要昂贵设备发展到现在仅基于微体系结构状态就能通过软件方式获取机密信息的访问模式,从而进一步推测出机密信息.TEE架构仅提供隔离机制,无法抵抗这类新出现的软件侧信道攻击.深入调研了ARM TrustZone、Intel SGX和AMD SEV这3种TEE架构的软件侧信道攻击及相应防御措施,并探讨其攻击和防御机制的发展趋势.首先,介绍了ARM TrustZone、Intel SGX和AMD SEV的基本原理,并详细阐述了软件侧信道攻击的定义以及缓存侧信道攻击的分类、方法和步骤;之后从处理器指令执行的角度,提出一种TEE攻击面分类方法,利用该方法对TEE软件侧信道攻击进行分类,并阐述了软件侧信道攻击与其他攻击相结合的组合攻击;然后详细讨论TEE软件侧信道攻击的威胁模型;最后全面总结业界对TEE软件侧信道攻击的防御措施,并从攻击和防御两方面探讨TEE软件侧信道攻击未来的研究趋势.     

Synthesis and properties of styrene–EPDM–vinyl acetate graft polymer

The styrene–EPDM–vinylacetate (SEV) graft polymer, which linked respectively the styrene (St) unit and vinylacetate the (VAc) unit to the ethylene–propylene–diene terpolymer (EPDM) backbone was synthesized by two‐step graft polymerizations: First the graft polymerization of VAc onto EPDM was carried out, and then St was added successively in the prepolymerized solution and further polymerized for a given period to obtain SEV. The effects of concentration of EPDM and an initiator, mole ratio of VAc to St, polymerization time, temperature, and solvent were examined on the graft polymerizations. The synthesized graft polymers (SEVs) that have different contents of St or VAc were identified by Fourier transform IR spectrum. The highest graft ratio has been obtained by 10 wt % of EPDM, 1.0 mole ratio of VAc to St, and 1.0 wt % of BPO in toluene for 48 h at 70°C. The glass transition temperature of SEV is lower than that of poly(vinyl acetate) (PVAc) and polystyrene (PS). The thermal stability of SEV is higher than that of PVAc, PS, and the acrylonitrile–butadiene–styrene (ABS) resin. The tensile strength of SEV was improved as compared with that of EPDM. The light resistance and weatherability of SEV were better than those of ABS. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2296–2304, 2000     

A survey of Intel SGX and its applications

This paper presents a comprehensive survey on the development of Intel SGX (software guard extensions) processors and its applications. With the advent of SGX in 2013 and its subsequent development, the corresponding research works are also increasing rapidly. In order to get a more comprehensive literature review related to SGX, we have made a systematic analysis of the related papers in this area. We first search through five large-scale paper retrieval libraries by keywords (i.e., ACM Digital Library, IEEE/IET Electronic Library, SpringerLink, Web of Science, and Elsevier Science Direct). We read and analyze a total of 128 SGX-related papers. The first round of extensive study is conducted to classify them. The second round of intensive study is carried out to complete a comprehensive analysis of the paper from various aspects. We start with the working environment of SGX and make a conclusive summary of trusted execution environment (TEE).We then focus on the applications of SGX. We also review and study multifarious attack methods to SGX framework and some recent security improvementsmade on SGX. Finally, we summarize the advantages and disadvantages of SGX with some future research opportunities. We hope this review could help the existing and future research works on SGX and its application for both developers and users.     

天然橡胶抗返原硫化体系的研究

研究了普通(CV)、有效(EV)、半有效(SEV)和平衡(EC)四种硫化体系对NR抗硫化返原和硫化胶物理机械性能的影响。结果表明：有效和平衡硫化体系的抗硫化返原性最好；在不同的硫化体系中加入抗返原剂Si69之后，都能有效地提高硫化天然胶的抗硫化返原性和物理机械性能。综合使用性能和抗硫化返原性，以半有效硫化体系较好。     

Gigacycle Fatigue Behavior of 1800 MPa Grade High Strength Spring Steel for Automobile Lightweight

Gigacycle fatigue behavior of 60Si2CrVA high strength spring steel was investigated by ultrasonic fatigue test machine. Fatigue fractography was observed by scanning electron microscopy （SEM）. Maximum inclusion sizes and fatigue strength in different volumes were estimated by statistics of extreme values （SEV） and generalized Pareto distribution （GPD） methods. The results showed that S N curves of 60Si2CrVA spring steels for two rolling processes were not horizontal asymptotes but a gradient in a regime of 109 cycles, and traditional fatigue limits were eliminated. Surface machined topography and inclusions in steel were major factors that led to elimination of fatigue limit for 60Si2CrVA spring steel. The SEV and GPD methods could effectively predict size of the maximum inclusion and fatigue strength in different volumes of 60Si2CrVA spring steel. Predicted fatigue strength was in accordance with experimental results by ultrasonic fatigue testing.     

硫化体系对EPDM耐热老化性能的影响

研究了普通硫化体系 (CV)、半有效硫化体系 (SEV)和有效硫化体系 (EV)的硫化特性及其对EPDM力学性能和耐热老化性能的影响 ,以及防老剂对EPDM耐热老化性能的影响。试验结果表明 ,采用SEV和EV体系硫化的硫化胶有较好的耐热老化性能 ,采用CV体系的硫化胶有较好的力学性能 ;防老剂对EPDM的耐热老化性能无明显影响。     

基于最大分类间隔SVDD算法的辐射源个体确认

通信辐射源个体确认技术是实现通信辐射源个体识别的关键技术之一。该文研究了基于支持向量数据描述(SVDD)的通信辐射源个体确认算法。针对传统SVDD算法在正类训练样本不完备的条件下对正类测试样本接受率较低的不足,提出带反类训练的最大分类间隔SVDD算法(MCM-SVDD)。MCM-SVDD在保证最小化超球体积的同时,使正类训练样本与反类训练样本距离超球表面的间隔最大化,从而提高了对正类测试样本正确接受的泛化能力。基于20台实际通信辐射源样本的实验表明,相对于SVDD, SVDD-neg和SVM, MCM-SVDD具有更高的平均确认率。     

超长寿命疲劳破坏行为的可靠性研究

为了进行超长寿命疲劳破坏行为的可靠性研究,对GCr15钢超长寿命疲劳S-N试验数据进行了统计评估,采用Bansqun模型描述了其S-N曲线关系,建立了其概率S-N曲线模型,并采用SEV方法和Murakami方程分别预测了钢中最大夹杂尺寸和其相对应的疲劳强度。结果表明:其超长寿命疲劳S-N数据能较好地服从三参数威布尔分布,其概率S-N曲线形式都呈现持续下降的趋势;在验证了最大夹杂尺寸服从Gumbel分布的基础上,SEV方法预测的最大夹杂尺寸随着钢体积的增大而线性增加,Murakami方程预测的结果揭示了其概率S-N曲线呈现持续下降的原因。     

裂解炉的先进控制方案及应用

分析了影响乙烯收率的主要因素,提出了以裂解深度为主要控制指标的先进控制方案,采用DCS实现裂解深度-裂解温度-燃料流量-燃料压力的四重串级调节系统,以燃料热值作为燃料流量控制的前馈补偿.用交叉限幅控制方案实现炉管的温差平衡控制.