一种基于有限域上的多项式分解定理的群签名方案

基于有限域上的多项式分解定理,给出一种新的群成员撤销方案.新方案的特点是:不需要群管理员和成员的交互;在成员增加和撤销过程中不改变成员的密钥;签名算法等同于一个普通签名,验证算法与撤销成员的个数无关.并分析了提出方案的安全性和性能.     

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。     

标准模型下可证安全的本地验证者撤销群签名方案

本地验证者撤销是一种有效的群成员撤销方法,该方法只需将撤销信息发给验证者而无需签名者的参与.目前大部分本地验证者撤销群签名方案都是在随机预言模型下证明方案的安全性,但是这种理想的预言机在现实世界中是不存在的,构造标准模型下可证安全的群签名方案仍是当前研究的热点课题.本文在Boyen- Waters群签名方案的基础上,提...     

密钥隔离的无证书聚合签名

无证书的聚合签名的提出是为了解决密钥托管问题以及复杂的证书管理问题.然而在无证书的聚合签名中,一旦某一签名者的密钥发生泄漏,所有由此签名者参与生成的聚合签名都将不再安全.为了减小无证书的聚合签名中密钥泄漏带来的危害,本文首次将密钥隔离安全机制嵌入到无证书的聚合签名中,提出了密钥隔离的无证书聚合签名的概念和安全模型,并给出了一个实用的方案,通过与协助器的交互,实现了对签名者密钥的定时更新.同时证明了方案在随机预言机模型下是安全的,即,满足密钥隔离安全、强密钥隔离安全和安全密钥更新的性质.     

实用的本地验证者撤销群签名方案

本地验证者撤销是一种有效的群成员撤销方法,该方法只需将撤销信息发给验证者而无需签名者的参与。目前本地验证者撤销群签名方案中普遍存在不能防止陷害攻击以及撤销验证计算量与撤销列表长度呈线性增长等问题。为了解决这些问题,并针对群签名在隐私保护证明方面的应用,基于q-SDH假设和DLDH假设,提出一种实用的本地验证者撤销群签名方案,并在随机预言模型下证明了方案的安全性。分析了方案的效率,并与现有的本地验证者撤销群签名方案进行了比较,分析表明方案的撤销验证计算量与撤销列表长度无关,同时还具有防陷害性和向后无关联性。     

证书认证中心管理证书的策略及实现

提出一种基于认证中心CA的网络安全解决方案,实现了以下功能:(1)认证中心的基本功能:证书的签发、证书的更新、证书的状态查询、证书的撤销、证书的归档等;(2)双证书机制,将用户的签名密钥对与加密密钥对相分离;(3)将用户签名私钥保存到用户证书载体.此方案不但解决了网上用户身份认证和信息安全传输的问题,而且更有效保护了用户的隐私,提高应用系统的安全性.     

一种高效的动态群签名方案

在群签名系统中如何有效删除成员是一个重要的研究课题,王尚平提出的成员删除方案虽然高效,但已被证明不能达到真正删除成员的目的。新方案基于王尚平等人的群签名成员删除方案原理,利用中国剩余定理对不同合法成员的特性密钥更新算子进行不同的加密处理,从而达到真正删除成员的目的。基于强RSA假设和大整数分解的困难性,新方案具有较高的安全性。     

HECC双线性对的特权集的门限群签名方案

针对HECC密码体制的优点,设计了一种基于HECC双线性对上含有特权集的门限群签名方案。该方案结合了门限群签名体制和双线性对,能有效地实现群成员的加入和撤销,并且可以在公钥环境下进行交互式的身份验证。具有用户私钥的验证简单、密钥短、保密性、合法签名的不可伪造性、签名者身份的匿名性并具有不可伪造性等重要优点。     

基于Mignotte''''s列的(t,n)门限群签名方案

电子学报中曾提出了一个在不改变其他有效群成员的签名密钥的情况下，可安全快速地加入或删除群成员的群签名方案。但此方案没有涉及到实际运用中需要设置门限的情况，现对原方案做了改进和推广，保留了原方案中可安全快速地加入或删除群成员的优点，推广到了每次参与签名人数变动较大，并需要设置门限的情况，利用中国剩余定理提出了一个新的基于Mignotte’s门限秘密共享方案的（t，n）门限群签名方案。     

授权群签名

现有的群签名方案都假设所有成员拥有相同的权限,不适用于成员权限不同的情形,该文提出授权群签名的概念,并给出一个具体的授权群签名方案.该文通过在一般群签名上增加一个负责授权的权限管理员和一个授权过程来达到授权群签名.在所给出的授权群签名方案中,签名人必须同时使用私钥和授权证书才能签名,因此只能按所授的权限签名,验证人则可通过权限公开证书对授权进行验证.     

Efficient Membership Revocation in ACJT Group Signature

How to find efficient and secure member- ship revocation algorithms is one of the most important issues standing in the way of real-world applications of group signatures. In this paper, the proof of knowledge of divisibility is given and a novel membership revocation method in ACJT group signature scheme is proposed： the group manager issues the product E of the public keys of current members in the group, when a group member wants to sign, he should not only proves that he has a membership certificate, but also proves that the public key in his certificate divides exactly the public key product E with zero knowledge. The proposed method is efficient since the group manager only needs one division and one exponentiation when a group member is deleted, while the signing and verifying procedure are independent of the number of current group members and excluded members, as well as the original group public key and membership certificates needn＇t be changed.     

Revocable identity-based proxy re-signature scheme in the standard model

User revocation is necessary to the practical application of identity-based proxy re-signature scheme.To solve the problem that the existing identity-based proxy re-signature schemes cannot provide revocation functionality,the notion of revocable identity-based proxy re-signature was introduced.Furthermore,the formal definition and security model of revocable identity-based proxy re-signature were presented.Based on proxy re-signature scheme and binary tree structure,a revocable identity-based proxy re-signature scheme was proposed.In the proposed,scheme,the user's signing key consists of two parts,a secret key and an update key.The secret key transmitted over the secure channel is fixed,but the update key broadcasted by the public channel is periodically changed.Only the user who has not been revoked can obtain the update key,and then randomize the secret key and update the key to generate the corresponding signature key of the current time period.In the standard model,the proposed scheme is proved to be existentially unforgeable against adaptive chosen-identity and chosen-message attacks.In addition,the proposed scheme has properties of bidirectionality and multi-use,and can resist signing key exposure attacks.The analysis results show that the proposed scheme can efficiently revoke the user and update the user’s key,and thus it has good scalability.     

一种基于中国剩余定理的群签名方案

在群签名方案中,群中任意成员可以代表整个群体生成签名.在有争议的情况下,群管理人可以确定签名人的身份.成员的撤消是群签名中的一个重要问题,在目前已知的各种撤消方案中,还不存在一种方案可以在不改变其它有效群成员的密钥的情况下,安全地撤消群成员.并且增加或撤消一个成员至少都需要指数运算,因此计算复杂度高.本文提出了一种基于中国剩余定理的群签名方案.该方案有三个特征:(1)在不改变其它有效群成员的密钥的情况下,可以安全地增加或撤消群成员;(2)增加或撤消的过程中只需要乘法运算,并且在撤消时群公钥的长度不变;(3)安全性是基于大数分解的困难性.     

An efficient forward secure group signature scheme with revocation

Up to now, how to construct an efficient secure group signature scheme, which needs not to reset the system when some group members＇ signing keys are exposed, is still a difficult problem. A construction concerning revocation of group members is an ideal one if it satisfies forward security which makes it more attractive for not sacrificing the security of past signatures of deleted members. This paper analyses the problem and gives a construction in which the group manager can be untrustworthy. The scheme is efficient even when the number of revoked members is large.     

A localized certificate revocation scheme for mobile ad hoc networks

The issue of certificate revocation in mobile ad hoc networks (MANETs) where there are no on-line access to trusted authorities, is a challenging problem. In wired network environments, when certificates are to be revoked, certificate authorities (CAs) add the information regarding the certificates in question to certificate revocation lists (CRLs) and post the CRLs on accessible repositories or distribute them to relevant entities. In purely ad hoc networks, there are typically no access to centralized repositories or trusted authorities; therefore the conventional method of certificate revocation is not applicable.In this paper, we present a decentralized certificate revocation scheme that allows the nodes within a MANET to revoke the certificates of malicious entities. The scheme is fully contained and it does not rely on inputs from centralized or external entities.     

一个基于中国剩余定理的群签名方案的攻击及其改进方案

该文给出了对一个已有的群签名方案的攻击,表明了已有的群签名不能防止群成员的联合攻击,在联合攻击下攻击者可以得到任何群成员的秘钥从而伪造任何人的签名。同时该方案也不能防止不诚实的管理员伪造群成员的签名。利用Schnorr签名方案给出了一种改进方案,新的改进方案具有以下特点:联合攻击下是安全的;可以防止不诚实的群中心伪造群成员的签名;可以简单高效地实现成员撤消。     

Certificate revocation and certificate update

We present a solution for the problem of certificate revocation. This solution represents certificate revocation lists by authenticated dictionaries that support: (1) efficient verification whether a certificate is in the list or not and (2) efficient updates (adding/removing certificates from the list). The suggested solution gains in scalability, communication costs, robustness to parameter changes, and update rate. Comparisons to the following solutions (and variants) are included: “traditional” certificate revocation lists (CRLs), Micali's (see Tech. Memo MIT/LCS/TM-542b, 1996) certificate revocation system (CRS), and Kocher's (see Financial Cryptography-FC'98 Lecture Notes in Computer Science. Berlin: Springer-Verlag, 1998, vol.1465, p.172-7) certificate revocation trees (CRT). We also consider a scenario in which certificates are not revoked, but frequently issued for short-term periods. Based on the authenticated dictionary scheme, a certificate update scheme is presented in which all certificates are updated by a common message. The suggested solutions for certificate revocation and certificate update problems are better than current solutions with respect to communication costs, update rate, and robustness to changes in parameters, and are compatible, e.g., with X.500 certificates     

对一种高效群签名方案的安全性分析

分析了张健红等人提出的高效群签名方案的安全性缺陷，撤销中心不能够打开一个有效的群签名，因此，群签名是不可跟踪的；其次，给出了对该群签名的一种联合攻击，群管理员和撤销中心合谋后可以任意产生有效的群签名并把它强加给任一群成员。分析结果表明，该群签名方案是不安全的。     

基于身份代理权可撤销的代理签名

代理签名体制中代理签名权的撤销问题至关重要,SONG等人提出一种可撤销代理权的代理签名方案。提出了一种新的基于身份的可撤销代理权的代理签名方案,原始签名者在发现代理签名者不诚实时,可以通过可信中心TA及时有效地撤销代理签名者的代理签名权,且在该方案中将用户个人信息作为身份标识,大大减少了密钥的存储和管理开销。