标准模型下基于认证的混合加密算法

为了构建一个较公钥基础设施(PKI)要求更为简单的公钥密码系统,Gentry提出了基于认证的公钥加密方案.在基于认证的公钥加密方案中,第三方对认证申请者的公钥或身份进行签名,并将该签名作为认证发送给申请者,申请者保留认证作为解密时的部分私钥.接收方对密文解密需要同时拥有第三方对其公钥的认证和接收方公钥对应的私钥,因而基于认证的加密方案同时具备基于身份加密方案中公钥的可认证性和传统公钥加密方案中私钥的免撤销性.基于Gentry身份加密算法提出一种高效、短公钥的基于认证的混合加密算法,新算法能在标准(非随机预言机)模型下被证明抗适应性选择密文攻击.     

基于认证的高效公钥加密算法

 2003年,Gentry提出基于认证的公钥加密方案.在基于认证的公钥加密方案中,第三方对认证申请者的公钥和/或身份进行签名,并将签名作为认证发送给申请者,申请者保存该认证作为解密时的部分私钥.接收方对密文解密需要同时拥有第三方对其公钥和/或身份的认证和接收方公钥对应的私钥,因此基于认证的加密方案同时具备基于身份加密方案的公钥可认证性和传统公钥方案中的私钥免撤销性.本文提出一种高效、紧凑的基于认证的公钥混合加密算法,新算法能在非随机预言机模型下被证明满足选择密文攻击安全.     

强安全无证书签名方案的安全性分析和改进

对王亚飞等人提出的强安全性无证书签名方案进行安全性分析,指出其方案难以抵抗不诚实KGC下的公钥替换攻击。针对此类问题,采用改变传统无证书算法顺序,以KGC公告板形式公开用户公钥,用户可以通过本地保存的私钥和公钥验证公钥的真实性,从而对KGC的行为进行约束。安全性分析表明,改进后的方案能够抵抗基于不诚实 KGC安全级别下的公钥替换攻击,而且方案避开了无双线性对和逆运算,效率优于已有方案。     

基于随机背包的公钥密码

该文构造了一个背包型公钥密码算法。该背包公钥密码具有如下优点:加解密只需要加法和模减法运算,因此加解密速度快;该算法是基于随机背包问题而不是易解背包问题而构造的;证明了在攻击者不掌握私钥信息情况下该密码算法能抵抗直接求解背包问题的攻击,包括低密度攻击和联立丢番图逼近攻击等;证明了攻击者能够恢复私钥信息与攻击者能够分解一个大整数是等价的。分析表明,该算法是一个安全高效的公钥加密算法。     

两种背包型的公钥密码算法的安全性分析

背包型公钥密码体制是几个最早的公钥密码体制之一,分析其安全性十分重要。该文对两种抵抗Shamir攻击和低密度攻击的背包型公钥密码体制进行了安全性分析,提出一种新的攻击方法,指出可以利用多项式时间算法以很大的概率找到私钥,从而破解了它们。     

基于变量组合的REESSE1-E签名方案

 文章介绍了互素序列的定义和杠杆函数的概念,描述了REESSE1-E签名方案的密钥生成、数字签名和身份验证三个算法,证明了验证算法的正确性,示范了如何利用变量之间的组合来构造难题.文章从五个主要方面分析了签名与验证的安全性,它包括从公钥推导私钥、从签名码提取私钥、仅通过公钥伪造签名码、通过已知签名码和公钥伪造另一个签名码以及通过选择消息伪造签名码等.分析表明基于变量组合的REESSE1-E签名方案的安全性等价于离散对数难题.     

LDPC码在加密系统中应用的约束条件

该文首先给出了基于LDPC码公钥加密系统中授权用户获取明文的置信传播迭代译码算法,并得出了在明文信息等概的情况下授权用户要成功获取明文,私钥所需满足的必要条件。然后根据置信传播递归迭代算法分析了公钥参数设计的充分必要条件。最后通过仿真验证了私钥和公钥参数设计的正确性。     

一种基于身份加密的可验证秘密共享方案

 提出了一种使用IBE公钥算法实现的可验证秘密共享方案.该方案中秘密分发者将IBE私钥作为共享秘密在接入结构中分发,任何参与者可以通过公开的验证信息验证影子秘密的正确性.随后在随机预言模型中证明了所提方案的语义安全性.理论分析和仿真实验表明,方案可以有效检测来自内外部攻击者的欺骗攻击,并具有较低的时间复杂度和通信开销.     

一个基于辫群的公钥密码算法

辫群是构造对抗量子公钥密码系统的新工具.已知的基于辫群共轭问题的公钥密码系统都受到不同程度的攻击.提出了一个基于辫群求根问题的公钥密码算法,随后对算法的正确性、安全性、参数选择和效率进行分析.新的公钥密码算法可以抵抗各种已知攻击.     

采用ECC算法CPK认证机制的安全支付方案

电子支付安全问题严重影响互联网服务水平的发展,针对传统公共密钥技术依赖第三方安全认证的问题,文章采用基于离散对数椭圆曲线算法的组合公钥机制,密钥管理通过离散对数椭圆曲线算法,生成种子公钥/私钥矩阵,通过密钥生成算法,生成公钥/私钥对,采用集中生产、分散分发、统一管理的方式解决密钥规模化生产和密钥管理的问题。通过密钥管理模块,对某原型系统进行支付安全认证方面的优化,最终通过黑盒测试方法进行系统功能测试,检验系统安全性是否得到了提高。     

Location privacy preserving scheme against attack from friends in SNS

In order to enrich the performance of the user's location information and to meet the diverse needs of users,a location privacy protection scheme based on attribute encryption was designed,which provided precise,more accurate,fuzzy and private four modes to manage the location information.The scheme was based on the algorithm of WT-CP-ABE.The location information was divided into three parts according to a close friend of grade,then the key infor-mation and position information was encrypted with attribute-based encryption and symmetric encryption method respec-tively and the ciphertext was published to the social network.The security of the scheme is analyzed,which shows that the scheme has the advantage of user attribute information confidentiality,data confidentiality and can resist the collusion attack.     

对一种双陷门加密体制的分析与改进

对一种具有双陷门解密机制的公钥概率加密体制的安全性进行分析,指出它存在三点不安全因素,不能抵抗选择密文攻击,攻击者通过选取适当的密文,在得到解密的明文后,能够计算出用户的私钥或分解模数,运用这些信息,攻击者可恢复所有的明文。同时,也对该加密体制作了改进,给出了一种能够抵抗适应性攻击的加密方案,防止攻击者利用获得的解密信息计算用户的私钥或分解模数,提高了加密体制的安全性。     

安全的无可信PKG的部分盲签名方案

利用gap Diffie-Hellman(GDH)群,在部分盲签名机制的基础上,提出了一个有效的基于身份的无可信私钥生成中心(PKG,private key generator)的部分盲签名方案.方案中PKG不能够伪造合法用户的签名,因为它只能生成一部分私钥.在随机预言模型下,新方案能抵抗适应性选择消息攻击和身份攻击下的存在性伪造,其安全性依赖于CDHP问题.该方案满足正确性和部分盲性,与Chow方案相比具有较高的效率.     

基于RSA的门限密钥托管方案

本文借鉴D.Boneh(1997)中密钥产生和Y.Desmedt(1991)中的密钥分拆思想,提出了一种有t个容错能力的(t+1,n)门限托管方案,方案可以避免阈下攻击,验证用户的托管密钥正确性,有效地检查出失效的托管代理,并具有密钥备份的能力。方案可用于多种通信方式。     

Forensic analysis of nonlinear collusion attacks for multimedia fingerprinting.

Digital fingerprinting is a technology for tracing the distribution of multimedia content and protecting them from unauthorized redistribution. Unique identification information is embedded into each distributed copy of multimedia signal and serves as a digital fingerprint. Collusion attack is a cost-effective attack against digital fingerprinting, where colluders combine several copies with the same content but different fingerprints to remove or attenuate the original fingerprints. In this paper, we investigate the average collusion attack and several basic nonlinear collusions on independent Gaussian fingerprints, and study their effectiveness and the impact on the perceptual quality. With unbounded Gaussian fingerprints, perceivable distortion may exist in the fingerprinted copies as well as the copies after the collusion attacks. In order to remove this perceptual distortion, we introduce bounded Gaussian-like fingerprints and study their performance under collusion attacks. We also study several commonly used detection statistics and analyze their performance under collusion attacks. We further propose a preprocessing technique of the extracted fingerprints specifically for collusion scenarios to improve the detection performance.     

一种基于中国剩余定理的群签名方案及其改进

陈泽文等人提出了一种基于中国剩余定理的群签名方案。文中认为,该方案可以在不改变其他有效成员签名密钥的情况下,增加或者撤销一个群成员,并且在撤销过程中不改变公钥的长度,可以抗击联合攻击、伪造签名等。但是研究发现,该方案在公共模上的疏忽,使其无法面对伪造签名攻击,并且存在在合谋情况下,实现将大整数n分解的概率算法,论文对其做出了改进。     

A Novel Blind Video Watermarking Scheme Based on Independent Dynamic Component

Video copyright protection has become important as it is possible to make unlimited copies of digital video without quality loss. Video watermark is the main method of video copyright protection. A novel blind video watermarking scheme is proposed in this paper, in which independent component analysis (ICA) is used to extract the common static component and relative dynamic component from the consecutive frames. And then a designed watermark is embedded into the wavelet coefficients of the obtained dynamic component according to the 4-neighboring-mean based algorithm. The binarization of the 3-level-approximate sub-image of the I-frame in each GOP (GOP-Group of Picture) is selected as the watermark for this GOP. Given such watermark, the scheme can easily resist copy attack and temporal synchronization. Besides, because the watermarks of different GOPs and their embedding positions in a GOP are different, the intra-video collusion attack can be resisted effectively and there is no possibility for inter-video collusion attack to succeed. The simulation shows the feasibility of this scheme, which can resist well temporal synchronization, copy attack, and collusion attack. Published online: February 2006     

基于动态累加器的异构传感网认证组密钥管理方案

利用动态累加器的证人能够证明特定累加项是否参与累加的特性,实现了组成员身份认证,提出了一种新的支持节点动态增加和撤销的组密钥管理方案DAAG。在需要建立组密钥时,所有成员节点提供自己持有的累加项,参与累加计算。DAAG方案在保证成员节点证人机密性的基础上, 通过绑定证人与组密钥更新计算,限制了非成员节点对新密钥的计算能力。安全性和性能分析表明,DAAG方案虽比FM方案消耗更多的通信代价,但能够抵抗伪造、重放和共谋等恶意攻击,提供前后向安全性。     

一种基于随机序列的公钥叛逆者追踪方案

基于离散对数困难问题,利用随机序列提出一种公钥叛逆者追踪方案。该方案采用多项式与过滤函数来构建,当缴获盗版解码器时,只需通过一次输入输出即可确定叛逆者。若需要撤销或恢复多个叛逆者时,其能在不更新其他合法用户私钥的前提下,实现完全撤销多个叛逆者或完全恢复已撤销用户。性能分析证明,该方案不仅存储、计算和通信开销低,还具有完全抗共谋性、完全撤销性与完全恢复性以及黑盒追踪的特点。     

One-way hash chain-based self-healing group key distribution scheme with collusion resistance capability in wireless sensor networks

In order to resolve the collusion resistance problem in the one-way hash chain-based self-healing group key distribution schemes and improve the performance of previous self-healing group key distribution schemes, we propose a self-healing group key distribution scheme based on the revocation polynomial and a special one-way hash key chain for wireless sensor networks (WSNs) in this paper. In our proposed scheme, by binding the time at which the user joins the group with the capability of recovering previous group session keys, a new method is addressed to provide the capability of resisting the collusion attack between revoked users and new joined users, and a special one-way hash chain utilization method and some new methods to construct the personal secret, the revocation polynomial and the key updating broadcast packet are presented. Compared with existing schemes under same conditions, our proposed scheme not only supports more revoked users and sessions, but also provides a stronger security. Moreover, our proposed scheme reduces the communication overhead, and is especially suited for a large scale WSN in bad environments where a strong collusion attack resistance capability is required and many users will be revoked.