可撤销属性的格基属性加密方案

针对量子环境下属性加密体制中属性撤销的问题,结合Zhang等提出的格上基于密文的属性加密方案,在格上构建了一个可撤销属性的格基属性加密方案。通过属性撤销列表,在二叉树结构下将未被撤销属性对应的密钥进行更新,从而达到撤销属性的目的。利用Shamir门限秘密共享的思想,实现了门限访问控制策略。该方案在随机预言机模型下是选择性安全的,安全性规约到错误学习问题。分析表明该方案在量子攻击下是安全的,并且支持灵活的门限访问控制策略。     

密文策略的权重属性基加密方案

在综合分析现有密文策略属性基加密方案的基础上,针对现有密文策略属性基加密方案较少考虑属性重要性的现状,将权重的概念引入到密文策略属性基加密方案中.授权机构依据属性在系统中的重要程度为其分配不同的权值,并依据属性的权值,通过属性转化算法将属性集合转化为属性权重分割集,利用线性秘密共享方法来实现密文策略权重属性基加密方案.提出了密文策略权重属性基加密方案的安全模型,在判定性双线性Diffie-Hellman指数假设下证明了该方案在标准模型下抵抗选择明文攻击的能力.密文策略权重属性基加密方案尽管在密文和密钥长度方面有所增加,但方案既可以支持细粒度的访问控制,又可以体现出属性的重要性,更加贴近于实际环境.     

一种可外包解密的高效密文策略的属性基加密方案

基于属性基的加密方案提供了一种对加密数据进行复杂访问控制的机制。但在大多数属性基加密系统中,密文长短和解密开销会随访问策略的复杂性而增加,限制了在资源有限的设备上运行程序。针对该问题,通过引入外包解密方法,构造了一个高效的、抗共谋攻击的可外包解密的密文策略的属性基加密方案,该方案在加密算法构造过程中引入线性密钥共享矩阵作为输入,并根据该矩阵选择随机指数,使得私钥随机分布,从而实现了抗共谋攻击,且方案在解密过程中引入了外包解密,只需要用户进行少量的计算便可得到密文相应的明文,从而很好解决了资源制约性问题。本文提出的安全证明是在非交互模型下、判定性平行双线性Diffie-Hellman幂元假设下进行的,且通过效率与安全性分析得出本方案拥有良好的性能。     

扩展的密文策略属性基加密机制

提出并描述了一种扩展的密文策略属性基加密(ECP-ABE)机制.对CP-ABE树形访问策略结构进行扩展,使其能够支持not和比较运算符表达式运算操作,显著增强了CP-ABE机制的访问控制能力.最后证明了所设计的ECP-ABE机制在标准模型下是适应性选择明文攻击(CPA)安全的,扩展的访问结构树不会给加密系统带来额外的安全问题.     

基于以太坊的格上属性基可搜索加密方案

提出了一种基于以太坊的安全、灵活、高效的格上属性基可搜索加密方案.方案基于格密码体制提出,解决了传统基于双线性配对技术的属性基可搜索加密方案存在的不可抗量子攻击安全问题.方案使用基于以太坊技术的分散存储方法解决了传统云存储系统中单点故障问题,并且方案中数据拥有者代替私钥生成器为用户生成私钥,这避免传统方案由于密钥托管问题造成的密钥滥用以及隐私泄露.采用以太坊的智能合约解决了以往属性基可搜索加密方案中云服务提供商不可信情况下关键字搜索结果的可靠性问题.与传统属性基可搜索加密方案相比,方案不仅可实现对加密关键字的细粒度检索,并且可抵抗量子攻击,增强了方案的安全性.在容错学习问题(learning with errors,LWE)假设下,证明了方案的安全性.     

面向个人健康记录的基于密文策略的权重属性加密方案

为实现对个人健康记录更高细粒度的访问,在基于属性加密的方案中加入权重的概念,授权机构根据属性在系统中的重要程度为属性分配相应的权值,进而得到属性集对应的权重集.利用访问控制树分层实现密文策略的权重属性加密,并在判定性双线性Diffie-Hellman假设下证明了该方案在标准模型下具有抵抗选择明文攻击的能力.该方案通讯量较大,但密文长度远小于现有方案,更适合计算能力弱的PHR系统.     

混合云模式下数据安全存储方案

针对混合云模式下数据安全存储与共享使用的问题,提出一种适用于混合云模式下的高效数据安全共享方案,该方案采用密文策略的属性基加密机制加密数据,通过私有云将密文数据存储在公有云上;移动用户访问云数据时,采用匿名密钥协商技术和委托加解密方法,保证用户对数据的快速访问.实验结果表明,本方案能够保证公有云上数据的安全存储,支持细粒度的访问控制,同时将大部分解密计算委托给私有云,减少移动云用户访问云数据的处理时间,使得其加解密时间为恒定值,不会随着属性的增多而线性增长.      

基于格的公钥加密与证书基加密简

证书基加密(CBE)结合了基于身份加密和公钥基础设施的各自优点,然而基于传统数学假设的CBE不能有效抵御量子算法的攻击.为此构建了一个基于格的CBE方案,可有效抵御量子算法的攻击.首先构建出一个基于格的公钥加密(PKE)方案,之后利用该PKE构建出基于格的CBE方案.该方案可被规约为格上的学习误差(LWE)问题,因此得到的CBE为随机不可区分选择明文攻击安全的.该方案是目前为止已知的第一个基于格的CBE方案.     

基于格的公钥加密与证书基加密

证书基加密(CBE)结合了基于身份加密和公钥基础设施的各自优点,然而基于传统数学假设的CBE不能有效抵御量子算法的攻击.为此构建了一个基于格的CBE方案,可有效抵御量子算法的攻击.首先构建出一个基于格的公钥加密(PKE)方案,之后利用该PKE构建出基于格的CBE方案.该方案可被规约为格上的学习误差(LWE)问题,因此得到的CBE为随机不可区分选择明文攻击安全的.该方案是目前为止已知的第一个基于格的CBE方案.     

云计算环境中基于策略的多用户全同态加密方法

全同态加密技术是解决云环境隐私安全问题的有效方法。考虑云环境下用户多样性特征,提出基于策略的多用户全同态加密方案(PB-MUFHE),该方案在全同态加密算法的基础上,通过在密文中设定适当的访问策略以及在密钥中设定属性,从而满足多用户密文的全同态运算以及多用户共享,并支持细粒度的访问控制。安全分析证明PB-MUFHE可以抵制共谋攻击,且在LWE困难度假设随机域模型下是IND-CPA安全的。性能评估表明:PB-MUFHE高效地实现密文数据的全同态运算,并能有效地支持访问控制和多用户共享。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with