Off-line dictionary attack on password-based authenticated key exchange protocols

In 2010,Lee et al proposed two simple and efficient three-party password-authenticated key exchange protocols that had been proven secure in the random oracle model.They argued that the two protocols could resist offline dictionary attacks.Indeed,the provable approach did not provide protection against off-line dictionary attacks.This paper shows that the two protocols are vulnerable to off-line dictionary attacks in the presence of an inside attacker because of an authentication flaw.This study conducts a detailed analysis on the flaw in the protocols and also shows how to eliminate the security flaw.     

基于口令的跨服务器认证密钥交换协议研究

为了满足某些特殊通信服务在跨服务器认证密钥交换时必须由客户直接协商产生会话密钥的要求,该文提出一种新的基于口令的跨服务器认证密钥交换协议。该协议对在线字典攻击的反应灵敏度及发现此类攻击的计算代价和通信代价低;分析结果表明,新协议满足基于口令的认证密钥交换协议的安全性要求。     

基于验证元的多密钥跨域交换协议

摘要:跨域的口令密钥交换协议(C2C-PAKE),可以使处于不同区域的用户通过不同的口令协商出共享会话密钥。本文针对大多数现存的跨域交换协议均需要依赖公钥密码算法效率较低的情况,在一个高效的三方密钥交换协议的基础上,提出了一个基于验证元的跨域密钥交换协议,该协议执行一次就能生成四把会话密钥,且无需使用公钥密码算法,与同类协议相比具有很高的效率。通过安全性分析证明,本文提出的协议能够抵御已知的各种攻击。     

Efficient Certificateless Authenticated Key Agreement Protocol from Pairings

0 IntroductionKey agreement protocol is vital to Web security,whichallows two communication parties (i .e.the Web cli-ent and Web server) to establish a secret session key overan open network. The session key,generated with contri-butions fromall the communicating parties ,is usually sub-sequently be used to achieve some cryptographic goal be-tweenthe Web clients and servers ,such as confidentialityor dataintegrity. The first two-party key agreement proto-col was first proposed by Diffie and…     

Security Analysis of Broadcaster Group Key Exchange Protocols

0 IntroductionAs a result of the increased development of network,group communication occursin many different settings .Anumber of group key exchange protocols have been pub-lished duringthelast years[1-11].This paper discusses thefirsttype; we calledit broadcaster protocols .Secure group communicationis not a si mple extension ofsecure two-party communication. They should provide dy-namic security that is the most complicated aspect . Groupcommunication mutates ( members leave and join) afte…     

一种贡献型的动态群密钥交换协议

利用DH(diffie hellman)问题、数字签名和哈希函数的内容,提出一种贡献型的动态群密钥交换协议,并对协议的安全性和计算效率进行了分析.所提出的协议中,每个群成员都贡献信息而生成会话密钥,协议能实现群成员的加入或离开.安全性分析表明,所提出的协议是安全的,能满足群密钥交换协议的安全性要求.协议效率比较分析表明所提协议的存储量和计算量都较小.     

代理可转换认证加密方案的改进

基于代理签名与可转换认证加密方案,任等(2005)提出了一种代理可转换认证加密和门限代理签名方案.在此指出了他们的方案是不安全的,原始签名人能够对任意的消息伪造有效的代理可转换认证加密签名.进一步,给出了改进方案以弥补他们方案的安全性缺陷.     

Efficient Authenticated Key Agreement Protocol Using Self-Certified Public Keys from Pairings

An efficient authenticated key agreement protocol is proposed, which makes use of bilinear pairings and selfcertified public keys. Its security is based on the security assumptions of the bilinear Diffie-Hellman problem and the computational Diffic-Hellman problem. Users can choose their private keys independently. The public keys and identities of users can bc verified implicitly when the session key being generating in a logically single step. A trusted Key Generation Center is no longer required as in the ID-based authenticated key agreement protocols. Compared with existing authenticated key agreement protocols from pairings, the new proposed protocol is more efficient and secure.     

Escrow-Free Certificate-Based Authenticated Key Agreement Protocol from Pairings

Key agreement protocols are essential for secure communications. In this paper, to solve the inherent key escrow problem of identity-based cryptography, an escrow-free certificate-based authenticated key agreement （CB-AK） protocol with perfect forward secrecy is proposed. Our protocol makes use of pairings on elliptic curves. The protocol is described and its properties are discussed though comparison with Smart＇s protocol.     

一种适用于基于身份的认证密钥协商的逆向防火墙协议

基于身份的认证密钥协商允许两方或者多方在不安全信道上建立安全的会话密钥。目前的认证密钥协商协议无法抵抗导致随机数泄露的后门攻击,比如已知特定于会话的临时攻击。基于此,我们设计了一种适用于基于身份的两方认证密钥协商的逆向防火墙协议。该协议在随机预言机模型下是安全的,能够抵抗强的临时会话秘密值泄露攻击,提供了消息抗泄露性。同时该协议不使用双线性对,节省了系统运行时间。最后,利用JPBC库实现了该协议。实验结果表明了该协议与同类型的协议相比,具有较小的带宽和较短的运行时间,十分适合应用于资源受限的系统中。     

一个具有完备前向安全性的基于口令认证密钥协商方案

在基于网络的分布式环境中,基于口令的认证密钥协商方案是一项基本的安全防护机制.对一个已有的基于口令的认证密钥协商方案[Chen T H,Hsiang H C,Shih W K.Securityenhancement on an improvement on two remote user authentication schemes using smart cards.Future Generation Computer Systems,2011,27(4):337-380]做了安全分析,指出其易受离线口令猜测攻击,并且不具备完备的前向安全性.在此基础上,提出了一个安全性增强的远程口令认证密钥协商方案.所提出的方案继承了已有方案的优良性质,能够抵抗离线口令猜测攻击,并且具有完备的前向安全性.经过安全分析,论证了所提出的方案具有强安全性,适合于在分布式环境中对用户和服务器提供双向认证和密钥协商.     

基于格的两方口令认证密钥交换协议

口令认证密钥交换协议能使共享低熵的通信方在开放的网络中建立安全的会话密钥,基于Gorce-Katz框架提出了基于格的两方口令认证密钥交换(password-based authenticated key exchange,2PAKE)协议,协议采用具有近似平滑投射哈希函数(approximate smooth projective Hash,ASPH)性质的选择明文攻击(chosen plaintext attack, CPA)安全的和带有标签的选择密文攻击(chosen ciphertext attack, CCA)安全的密码体制,利用平滑投射函数的纠错性生成随机参数,通过伪随机函数计算会话密钥;与同类协议相比,该方案降低客户端密钥长度,减少服务器端投射密钥的生成次数,具有较高的效率以及完美前向安全性,在抵抗量子攻击的同时可实现显式双向认证。     

基于口令的抵抗字典攻击的密钥交换协议

口令是INTERNET常用的用户身份验证方式,字典攻击方式是攻击者进行口令猜测的常用方法．本文提出了一种基于口令的抵抗字典攻击的密钥交换协议,首先对协议双方的身份进行认证,然后在两者之间生成一个随机密钥用于对后续的会话进行加密．     

一种基于身份可认证两方密钥协商方案

为了降低计算开销,提高安全性,通过 Diffie-Hellman 协议建立密钥共享,结合用户身份信息,以 VBNNIBS 签名思想作为基础,提出了一种可认证的两方密钥协商方案。密钥生成中心 KGC 结合用户身份信息仅为用户生成部分私钥和公钥,其完整的私钥和公钥由用户结合自己的长期私钥生成,安全性基于椭圆曲线离散对数问题。方案中无双线性对运算,只需椭圆曲线上4次点乘运算、1次模运算、3次哈希运算,通信双方只需2次通信就可实现双方认证和密钥协商,提高了密钥产生的效率。分析表明,该方案具有完美前向保密性、抗密钥泄露伪装攻击、已知会话密钥通信安全、非密钥控制、抗重放攻击等安全属性。性能及安全性比较表明,该方案在安全性和性能方面具有较大的优势,适用于资源受限的无线网络通信环境中。     

基于身份的多服务器认证密钥协商方案

将基于身份的密码体制与远程多服务器密钥协商相结合,提出一种基于身份的远程多服务器密钥协商方案.用户注册时由私钥生成中心颁发私钥并安全存放于智能卡中.用户登录服务器前,双方采用基于身份的双线性配对计算进行双向身份认证,并协商生成会话密钥.服务器端无须保存口令表,用户端无须建立数据表存储相关登录信息,无须在终端能离线更改登录口令.该方案减少了密钥协商的通信开销、计算开销以及存储开销,在标准BR安全模型下该方案被证明是安全的.     

Practical Encrypted Key Agreement Using Passwords

0 IntroductionWith rapid development on the Internet a user Bob caneasily access the networkto get some services fromaservice provider ,or toretrieve his sensitive private data storedinthe server previously.In that case,he has to establish se-cure session keys with remote servers . To verify the identity(IDfor short) of a user manyreal systems use password-basedauthenticated key exchange protocol . The fundamental prob-lems with passwords come from the fact that most users’passwords are dra…     

基于群组通信的通用阈值签名和鉴别加密技术分析

针对Wang等人提出的基于群组通信的通用阈值签名以及鉴别加密技术(W—C—L方案)，从两方面证明了该方案的不可靠性：首先，W—C—L不能抵制住他们所声称的方程攻击；其次，W—C—L不是一个真正的门限共享验证。针对最近Tseng等人提出的基于W—C—L的改进算法(T—J—C方案)，说明了该方法也会遭受方程攻击。     

基于双线性对和公钥自证明的认证加密方案

目前,在有限域上非奇异椭圆曲线离散对数问题还没有有效的攻击方法,使其在加密技术中得到了广泛应 用。提出了一种基于双线性对和公钥自证明的认证加密方案。该方案中,用户签名前不需要进行身份认证,接收 者在认证签名#恢复消息时实现通信双方的身份认证,减少了通信量。同时,该方案将自证明公钥体制推广到椭圆 曲线域,同样长度的密钥具有更高的安全性,在网络通信、电子商务以及IC卡等领域具有广泛的应用前景。     

Provable Efficient Certificateless Group Key Exchange Protocol

Certificateless public key cryptography （CL-PKC） avoids the inherent escrow of identity-based cryptography and does not require certificates to guarantee the authenticity of public keys. Based on CL-PKC, we present an efficient constant-round group key exchange protocol, which is provably secure under the intractability of computation Diffie-Hellman problem. Our protocol is a contributory key exchange with perfect forward secrecy and has only two communication rounds. So it is more efficient than other protocols. Moreover, our protocol provides a method to design efficient constant-round group key exchange protocols and most secret sharing schemes could be adopted to construct our protocol.     

一种新的单/多密钥交换协议

文章提出一种新的无散列函数单/多密钥交换协议;该协议同Diffie-Hellm an协议一样都是建立在离散对数问题上的,具有较好的安全性;该协议具有身份认证功能,可以避免Diffie-Hellm an协议中存在的漏洞——中间人攻击,而且它既可以进行单密钥交换又可以进行多密钥交换。