标准模型下可证明安全的分级身份签名方案

为使分级身份签名方案能够获得高安全性并同时缩短签名长度、降低计算量,提出一种标准模型下可证明安全的分级身份签名方案.现有的方案通常在签名过程中将消息作为一个整体进行运算,而文中方案则对消息进行分段处理,使得方案不仅具有效率上的优势,同时在相同的效率级别上,安全性明显优于其他现有方案.方案的安全性优势体现在:安全性证明基于完全身份的标准模型,安全性规约于计算Diffie-Hellman(CDH)假设,并且CDH假设的安全性明显优于其他的困难假设而仅次于离散对数问题,因此方案具有较强的安全性.方案的效率优势体现在:签名长度为常数,验证过程只需要进行3次双线性对运算,用户私钥长度随着级数的增加而减少.性能分析和安全性分析表明,文中方案的安全性和效率均优于现有方案.     

标准模型下基于身份的盲签名方案

由于随机预言模型实现过程存在安全缺陷,提出一种标准模型下基于身份的安全盲签名方案.方案中首先定义基于身份盲签名的安全模型;然后利用双线性对构建盲签名方案;最后,在标准模型下给出基于CDH假设的方案安全性证明.因此,在自适应选择消息和身份攻击下,该方案是安全的.     

多PKG环境下无双线性对的基于身份AKA协议

提出一种多PKG环境下无双线性对的基于身份AKA协议, 且在随机预言模型下, 将协议的安全性证明规约到标准的计算性CDH假设。提出了相应的基于身份XCR与DCR签名体制, 通过对两处体制进行安全性证明, 实现对新协议的安全性证明。通过与已有协议的相关性能比较体现了新协议的优点。     

无证书一次代理签名(英文)

为了解决密钥托管问题,Al-Riyami和Paterson提出了无证书签名方案.通过修改陆等人基于身份的一次代理签名方案密钥的产生算法,提出了无证书一次代理签名方案,并且正式定义了无证书一次代理签名方案的安全模型.在随机预言机模型下,证明方案的安全性依赖于CDH困难问题.     

在标准模型下安全的基于身份的代理签名方案

代理签名允许原始签名人把他的签名权委托给代理签名人, 这样代理签名人能够代表原始签名人对消息进行签名. 代理签名可以应用到许多领域, 例如分布式系统, 网格计算和移动代理等. 将代理签名与基于身份的密码学结合起来, 人们提出了一些基于身份的代理签名方案, 可是它们的安全性证明都是在随机预言模型下获得的, 这样它们在现实环境中不一定是安全的. 利用Paterson等的基于身份的签名方案构造了一个基于身份的代理签名方案, 并在标准模型下基于计算Diffie-Hellman假设证明了它的安全性.     

无证书一次代理签名

为了解决密钥托管问题,Al-Riyami和Paterson提出了无证书签名方案.通过修改陆等人基于身份的一次代理签名方案密钥的产生算法,提出了无证书一次代理签名方案,并且正式定义了无证书一次代理签名方案的安全模型.在随机预言机模型下,证明方案的安全性依赖于CDH困难问题.     

一个基于分级身份的密码系统

提出一个基于分级身份的密码系统:包括分级的基于身份的加密和签名方案。在随机预言模型下,新的基于分级身份的加密和签名方案都是可证明安全的,同时在标准模型下,基于分级身份的加密方案是在给定身份攻击下可证明安全的。基于给出的基于分级身份的加密方案,首次提出了分级代理解密的概念,并且给出了安全模型和构造方法。     

新的无证书的门限代理签名方案

门限代理签名是代理签名与门限签名结合产生的签名体制,具有分配代理签名权力和分散代理密钥的优点.无证书密码体制既保持基于身份的密码体制不需要使用公钥证书的优点,又较好解决基于身份公钥体制所固有的密钥托管问题.文章将无证书签名方案和门限代理签名方案结合,提出一个新的无证书门限代理签名方案,新方案具有安全、高效的特性.     

一种新的基于椭圆曲线的门限群签名方案

在门限群签名体制中,任何t或多于t个成员合作就可以产生一个有效的群签名.基于椭圆曲线离散对数问题的难解性,提出了一个安全、有效的门限签名方案.与现有的基于椭圆曲线离散对数问题的门限签名方案相比,提出的方案具有以下优势:在可信中心TC的帮助下能够追踪到签名者的身份;t个成员合谋攻击不能伪造其他成员的签名也无法获取系统的全部秘密;系统具有一定的稳定性.     

标准模型下基于身份的门限密钥隔离签名

为了减轻基于身份的签名系统中密钥泄漏所带来危害,运用Weng等的门限密钥隔离机制设计了一个基于身份的门限密钥隔离签名方案.所提方案的安全性证明是基于标准模型的,即不需要随机预言机.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that