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283 个结果
  • 简介:Patarinproposedthedragonscheme,pointedouttheinsecurityofthedragonalgorithmwithonehiddenmonomialandsuggestedacandidatedragonsignaturealgorithmwithacomplicatedfunction.Thispaperpresentsanalgebraicmethodtoattackthecandidatedragonsignaturealgorithm.TheattackborrowsthebasicideaoftheattackduetoKipnisandShamir,andutilizestheunderlyingalgebraicstructureofthecandidatedragonsignaturealgorithmovertheextensionfieldtoderiveawaytoenablethevariableYbeviewedasafixedvalue.Theattackrecoverstheprivatekeysefficientlywhentheparametersaren≤25andD=[logqd]≤3.

  • 标签: 安全性分析 签名算法 代数方法 代数结构 候选人 隐藏
  • 简介:环境变化被期望由决定幼苗建立和成功转移分发和许多植被。然而,很当前的生态系统模型仅仅在biogeophysics上集中于不能生活的因素的影响(例如,全球分发,等等),在人口动力学忽略他们的角色(例如,幼苗建立率,死亡率,等等)生态的社区。如此的疏忽可以在生态系统人口动力学导致偏爱(例如在为在森林生态系统的木质的种类的人口密度的变化)并且特征。在现在的学习,为作为功能而非阀值介绍土壤水的一个新建立计划被开发并且验证,用象一张测试床的版本1.0IAP-DGVM。结果证明在建立计划的土壤水在森林转变地区上有显著影响。与原来的计划相比,新计划显著地改进了树人口密度的模拟,特别在森林和转变地区的外部区域。因而,在森林里偏导部分范围在约78.8%全球格子房间被减少。在相对偏爱从34.3%~4.8%被减少的地方,树,灌木,草和赤裸的土壤的全球模仿的区域分别地更好表现了,从27.6%~13.1%,从55.2%~9.2%,并且从37.6%~3.6%。而且,新计划有更合理的相关性在吝啬的年度降水上种功能的类型(PFT),并且在亚马逊和中央非洲的热带雨林外设区域描述了正确主导的PFT。

  • 标签: 立方 森林生态系统 生态系统模型 植物功能型 土壤水分 非生物因素
  • 简介:Inthispaper,asubdivisionschemewhichgeneralizesasurfaceschemeinpreviouspaperstovolumemeshesisdesigned.Theschemeexhibitssignificantcontrolovershrink-age/sizeofvolumetricmodels.Italsohastheabilitytoconvenientlyincorporateboundariesandcreasesintoasmoothlimitshapeofmodels.ThemethodpresentedhereismuchsimplerandeasierascomparedtoMacCrackenandJoy's.Thismethodmakesnorestrictionsonthelocaltopologyofmeshes.Particularly,itcanbeappliedwithoutanychangetomeshesofnonmanifoldtopology.

  • 标签: 表面细分 体积测定模型 特征控制 局部拓扑流形
  • 简介:Oneoftheopenissuesinprincipleschemedesignofmechanicalsystemsisprinciplerepresentation,whichnotonlyoutliesthephysicalprinciples,butalsofacilitatesthedesignsynthesis.Anenergy-basedapproachtorepresentprincipleschemedesignisproposed.Firstly,anenergyinteractionmodelofmechanicalsystemsisestablishedandanintermediatemodelisderived,inwhichprincipleschemedesignistransformedintosolvingtheenergyfunctionsofsystem.Thentheenergyfunctionsaremodeledwiththelanguageofbondgraphs,andprinciplerepresentationforcomponenytsispresented.Finally,characteristicsofthedevelopedrepresentationapproachareanalyzedandadesignexampleofgatedrivesystemisgiventodemonstratethisapproach.

  • 标签: CAD 计算机辅助设计 功能函数 主方案设计
  • 简介:The’polarcoding’proposedbyDr.Arkancanachievethesymmetriccapacityofbinary-inputdiscretememorylesschannels(B-DMC).ThegeneratormatrixofpolarcodesisGN=BNFnforN=2n,BNwasapermutationmatrix.Inthearticleitwasrealizedwithaninterleaver,sothematrixproductionofGNwasavoided;thenthegeneratormatrixwasjustdeterminedbythematrixFnwhichwasconstructedwiththreesub-matrixesofFn-1andone2N-1orderzeromatrix,itwasdealwithfastHadamardtransform(FHT)algorithm.Thecomplexityofthenewschemewasreducedsharply,andaniterativealgorithmalsocanbeused.TheexampleshowedthatwhenN=8,complexityoftheencodingschemewasjust16whichisobviouslylessthanthatoforiginalencodingscheme36.

  • 标签: 编码方案 极地 生成矩阵 迭代算法 阿达玛变换 记忆能力
  • 简介:ThisarticledescribesalocalerrorestimatorforGlimm'sschemeforhyperbolicsystemsofconservationlawsandusesittoreplacetheusualrandomchoiceinGlimm'sschemebyanoptimalchoice.Asaby-productofthelocalerrorestimator,theprocedureprovidesaglobalerrorestimatorthatisshownnumericallytobeaveryaccurateestimateoftheerrorinL1(R)foralltimes.Althoughthereispartialmathematicalevidencefortheerrorestimatorproposed,atthisstagetheerrorestimatormustbeconsideredad-hoc.Nonetheless,theerrorestimatorissimpletocompute,relativelyinexpensive,withoutadjustableparametersandatleastasaccurateasotherexistingerrorestimators.Numericalexperimentsin1-DforBurgers'equationandforEuler'ssystemareperformedtomeasuretheasymptoticaccuracyoftheresultingschemeandoftheerrorestimator.

  • 标签: 局部误差估计 自适应 作者 版本 双曲守恒律 随机选择
  • 简介:Luby和Rackoff由用一大随机的功能代替每圆功能理想化DES。在这篇论文,作者由用一小随机的功能代替每S盒子理想化山茶,它被称为像山茶的计划。five-roundCamellia-like计划是假散乱,八回合的像山茶的计划为适应对手是超级假散乱的,这然后被证明。进一步,纸考虑Camellia-likescheme的更有效的建设,并且讨论怎么构造假散乱从更少的随机的像山茶的计划工作。

  • 标签: 块密码 随机函数 伪随机性 DES 数据加密标准
  • 简介:Inubiquitouscomputing,datashouldbeabletobeaccessedfromanylocation,andthecorrectnessofdatabecomesvitalduringthecommunication.Supposethatmanyuserssigndifferentmessagesrespectively,beforeforwardingorsendingthesemessages,thentheverifiermustspendalotofcomputingtimetoverifytheirsignatures.Consequently,theaggregatesignatureschemeisaneffectivemethodofimprovingefficiencyinthiskindofsystems,whichprovidestheconveniencefortheverifier.Inthispaper,weproposeanewcertificatelessaggregatesignatureschemewhichisefficientingeneratingasignatureandverification.ThisschemeisprovablysecureundertheextendedcomputationalDiffie-Hellmanassumption.

  • 标签: 签名方案 DIFFIE-HELLMAN假设 聚合 证书 计算时间 可证明安全
  • 简介:隐私是在电子投票的一个重要问题。在电子投票的完整的隐私的概念第一被建议,不是仅仅选民的隐私被担心,而且候选人的。没有任何信任第三方,保存电子选举建筑学的隐私被介绍,为k-out-of-m选举的一种一般技术也基于分布式的ElGamal加密和混合火柴被提供。没有揭示他们的愿望和输的候选人的投票,选民能自己计算结果。而且,获胜者候选人的投票是否多于一半,能直接被验证。这个计划满足投票并且去模式并且完成完整的隐私。正确性和安全也被分析。

  • 标签: 隐私保护 电子投票 候选人 第三方 分布式 获奖者
  • 简介:Vehielesenlistedwitheomputing,sensingandcommunicatingdevicescancreatevehicularnetworks,asubsetofcooperativesystemsinheterogeneousenvironments,aimingatimprovingsafetyandentertainmentintraffic.Invehicularnetworks,avehicle’sidentityisassociatedtoitsowner’sidentityasauniquelinkage.Therefore,itisofimportancetoprotectprivacyofvehiclesfrombeingpossiblytracked.Obviously,theprivacyprotectionmustbescalablebecauseofthehighmobilityandlargepopulationofvehicles.Inthiswork,wetakeanon-trivialsteptowardsprotectingprivacyofvehicles.Asprivacydrawspublicconcerns,wefirstlypresentprivacyimplicationsofoperationalchallengesfromthepublicpolicyperspective.Additionally,weenvisionvehicularnetworksasgeographicallypartitionedsubnetworks(cells).Eachsubnetworkmaintainsalistofpseudonyms.Eachpseudonymincludesthecell’sgeographicidandarandomnumberashostid.Beforestartingcommunication,vehiclesneedtorequestapseudonymondemandfrompseudonymserver.Inordertoimproveutilizationofpseudonyms,weaddressastochasticmodelwithtime-varyingarrivalanddeparturerates.Ourmaincontributionincludes:1)proposingascalableandeffectivealgorithmtoprotectprivacy;2)providinganalyticalresultsofprobability,varianceandexpectednumberofrequestsonpseudonymservers.Theempiricalresultsconfirmtheaccuracyofouranalyticalpredictions.

  • 标签: 隐私保护 车载网络 可扩展性 通信设备 异构环境 合作系统
  • 简介:Theperformanceofmassivemultiple-inputmultiple-output(MIMO)systemislimitedbypilotcontamination.Toreducethepilotcontamination,uplinkanddownlinkprecodingalgorithmsareputforwardbasedoninterferencealignmentcriterion.Intheuplinkreceivingprocessing,thetargetfunctionalignsthepilotcontaminationandtheinterferencesignalstothesamenullspaceandacquiresthemaximalspacedegreeofthedesiredsignals.Theuplinkreceivingprecodingmatrixissolvedonmaximalsignaltointerferenceplusnoiseratio(SINR)criterionconsideringtheimpactofthepilotcontaminationonchannelestimations.Theuplinkreceivingprecodingmatrixisusedasthedownlinktransmittingprecodingmatrix.Exploitingthechannelreciprocity,itisprovedthat,iftheuplinkreceivingprecodingmatrixachievesmaximalSINR,theidenticalprecodingmatrixcanbeusedinthedownlinktransmissionandacquiresmaximalsignaltoleakageplusnoiseratio(SLNR).Simulationsshowthatthespectrumefficiencyoftheproposedalgorithmcanreachabout1.5timeshigherthanthatofpopularmatchedfiltering(MF)precodingalgorithm,andabout1.1timeshigherthanmulti-cellminimummeansquareerror(MMSE)precodingalgorithm.Theperformanceoftheproposedalgorithmcanbeimprovedapproximatelylinearlywiththeincreasingofthenumberofantennas.

  • 标签: MIMO系统 干扰信号 对齐 编码算法 上行链路 编码矩阵
  • 简介:存取控制计划被建议让系统宽信息管理(游泳)在实际应用程序处理属性撤回的问题。把基于的加密(ABE)基于属性,这个计划介绍代理重新加密机制和关键加密钥匙(KEK)树与属性撤回认识到有细密纹理的存取控制。这份报纸根据民用的航空的现状定义属性。与以前建议的一些另外的计划相比,这个计划不仅弄短密文(CT)和私人钥匙的长度而且改进加密和解密的效率。计划能抵抗串通攻击并且在游泳保证数据的安全。

  • 标签: 游泳 存取控制 代理重新加密 属性撤回
  • 简介:Quantumalgorithmsbringgreatchallengestoclassicalpublickeycryptosystems,whichmakescryptosystemsbasedonnon-commutativealgebraicsystemshoptopic.Thebraidgroups,whicharenon-commutative,haveattractedmuchattentionasanewplatformforconstructingquantumattack-resistantcryptosystems.Aringsignatureschemeisproposedbasedonthedifficultyoftherootextractionproblemoverbraidgroups,whichcanresistexistentialforgeryagainsttheadaptivelycho-sen-messageattackundertherandomoraclemodel.

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