强安全性的三方口令认证密钥交换协议

基于可证明安全的AugPAKE协议,提出一种具有强安全性的三方口令认证密钥交换(3PAKE)协议,协议中避免使用服务器的公钥进行认证,以保证执行效率.安全性分析结果表明,该协议可抵抗字典攻击、服务器泄露攻击等已知攻击,并具有对服务器的密钥保密性以及前向安全性.在随机预言模型下,基于DDH、SDH假设证明了该协议的安全性.     

改进的三方口令认证密钥交换协议

基于三方的口令认证密钥交换（3PAKE）协议是客户通过与可信服务器共享一个口令验证元,在两客户进行通信时通过此可信服务器进行会话密钥的建立与共享,从而进行通信。首先对李文敏等人提出的协议进行安全性分析,发现该协议易受离线字典攻击和服务器泄露攻击。提出了一个改进协议,该协议能够提供双向认证、会话密钥机密性和前向安全性,能够有效抵抗多种攻击,包括离线字典攻击和服务器泄露攻击。     

一种新的跨域C2C-PAKE协议

跨域客户到客户基于口令认证的密钥交换（C2C-PAKE）协议具有重要的应用价值。但是,目前的大部分C2C-PAKE协议都无法抵抗口令泄露攻击。该文给出了一个新的跨域客户到客户的口令认证密钥交换协议。该协议带有签名体制且交互次数较少。随后,在一般模型下对给出的协议进行了安全性证明。该协议可以抵抗口令泄露等各种攻击,并且具有前向安全性质。     

改进的三方口令验证元认证密钥交换协议

在三方口令认证密钥交换（三方PAKE）协议中,每个用户仅仅需要和服务器共享一个口令,就可以在服务器的协助下与他人进行安全的密钥交换.由于有效地减少了用户管理口令的负担,三方PAKE协议在大规模用户集的安全通信中受到了较多关注.然而,已有的三方PAKE协议大多关注的是服务器利用明文存储用户口令的情形,没有考虑服务器口令文件泄露所造成的巨大威胁.在服务器端存放的是相应于用户口令的验证元的情形下,研究三方PAKE协议的分析和设计.首先分析了一个最近提出的基于验证元的三方PAKE协议,指出该协议易于遭受离线字典攻击,因此未能达到所宣称的安全性;其次,在分析已有协议设计缺陷的基础上,提出了一个新的基于验证元的三方PAKE协议,并在标准模型下证明了所设计的协议的安全性,与已有协议的比较表明,新提出的协议在提供了更高安全性的同时具有可接受的计算和通信效率.     

基于椭圆曲线的加密密钥交换协议

加密密钥交换协议(EKE)的目的是利用安全性低的口令协商安全性高的密钥,进而利用密钥对以后的通信进行加密或身份认证,从而实现安全通信.基于验证元的EKE是针对服务器泄露攻击问题提出的.本文基于椭圆曲线密码系统的特点,给出了一个基于验证元的3EKE,该协议中,服务器通过口令实现对用户的认证;协议能够抵抗服务器泄露等攻击,...     

简单的三方口令密钥交换协议

基于口令认证的三方密钥交换协议（3PAKE）是通信双方在认证服务器的帮助下能在公开非安全的信道上协商并建立一个共享会话密钥。虽然目前有不少该方面的研究,但多数后来被证实易受攻击。本文给合以往的研究,提出一个不需服务器公钥体系的简单的基于口令认证的三方密钥交换协议。本文的协议不仅能抵抗各种攻击,而且计算成本和通信成本都比较低。     

对两个口令认证密钥交换协议的安全性分析

口令认证密钥交换协议使得仅共享低熵口令的用户可以通过不安全的信道安全地协商出高熵的会话密钥,由于实用性较强受到了密码学研究者的广泛关注。对最近在“标准模型下高效的基于口令认证密钥协商协议”一文中提出的协议以及在“基于验证元的三方口令认证密钥交换协议”一文中提出的协议进行了分析,指出这两个口令认证密钥交换协议都是不安全的,难于抵抗离线字典攻击,进一步分析了原协议设计或安全性证明中被疏忽之处。     

基于百万富翁算法的口令认证密钥交换协议

口令认证密钥交换（PAKE）协议由于其便于记忆、运行成本低等特点受到广泛关注。文章在百万富翁协议算法的基础上,通过简化和改进,提出一种口令认证的密钥交换协议。该协议使用一个低熵的口令进行双方的认证,并得到一个高熵的密钥。文章同时分析了该协议对抵御中间人攻击和离线字典攻击的安全性。     

具有强匿名性的网关口令认证密钥交换协议

网关口令认证密钥交换协议允许用户和网关在服务器的协助下建立起一个共享的会话密钥,其中用户和服务器之间的认证通过低熵的口令来完成.已有的网关口令认证密钥交换协议对用户的匿名性研究不足.该文基于Diffie-Hellman密钥交换提出了具有强匿名性的网关口令认证密钥交换协议,并且在随机预言模型下基于标准的DDH假设证明了协议的安全性.新协议可以抵抗不可检测在线字典攻击并且计算效率高,安全性和计算效率都优于已有的同类协议.     

基于椭圆曲线的跨域端到端口令认证密钥协商协议

跨域端到端口令认证密钥协商协议(C2C-PAKA)的主要目的是使分布在不同域中持有不同口令的两个客户端可以在各自服务器的协助下实现相互认证并协商出共同的会话密钥。本文中,我们基于椭圆曲线上的离散对数问题,在直接通信架构下给出一个跨域的口令认证的密钥协商协议。该协议中,诚实的服务器是不能获取任何关于会话密钥的值。各参与方之间能够实现相互认证。与同类协议比较,该协议具有较小的通信负担和计算负担,更易于实现。此外,协议还能够抵抗字典攻击、口令泄露模仿攻击和未知会话密钥共享攻击等通用攻击类型,同时能够实现前向安全、无密钥控制和已知会话密钥安全等安全属性。     

Cryptanalysis of simple three-party key exchange protocol

Recently, Lu and Cao published a novel protocol for password-based authenticated key exchanges (PAKE) in a three-party setting in Journal of Computers and Security, where two clients, each shares a human-memorable password with a trusted server, can construct a secure session key. They argued that their simple three-party PAKE (3-PAKE) protocol can resist against various known attacks. In this paper, we show that this protocol is vulnerable to a kind of man-in-the-middle attack that exploits an authentication flaw in their protocol and is subject to the undetectable on-line dictionary attack. We also conduct a detailed analysis on the flaws in the protocol and provide an improved protocol.     

Provably secure three-party password authenticated key exchange protocol in the standard model

Three-party password authenticated key exchange protocol is a very practical mechanism to establish secure session key through authenticating each other with the help of a trusted server. Most three-party password authenticated key exchange protocols only guarantee security in the random oracle model. However, a random oracle based cryptographic construction may be insecure when the oracle is replaced by real function. Moreover, some previous unknown attacks appear with the advance of the adversary capability. Therefore, a suitable standard model which can imitate a wider variety of attack scenarios for 3PAKE protocol is needed. Aim at resisting dictionary attack, unknown key-share attack and password-compromise impersonation attack, an expanded standard model for 3PAKE protocol is given. Meanwhile, through applying ElGamal encryption scheme and pseudorandom function, a specific three-party password authenticated key exchange protocol is proposed. The security of the proposed protocol is proven in the new standard model. The result shows that the present protocol has stronger security by comparing with other existing protocols, which covers the following security properties: (1) semantic security, (2) key privacy, (3) client-to-server authentication, (4) mutual authentication, (5) resistance to various known attacks, and (6) forward security.     

Cryptanalysis of simple three-party key exchange protocol (S-3PAKE)

Password-authenticated key exchange (PAKE) protocols allow parties to share secret keys in an authentic manner based on an easily memorizable password. Recently, Lu and Cao proposed a three-party password-authenticated key exchange protocol, so called S-3PAKE, based on ideas of the Abdalla and Pointcheval two-party SPAKE extended to three parties. S-3PAKE can be seen to have a structure alternative to that of another three-party PAKE protocol (3PAKE) by Abdalla and Pointcheval. Furthermore, a simple improvement to S-3PAKE was proposed very recently by Chung and Ku to resist the kind of attacks that applied to earlier versions of 3PAKE. In this paper, we show that S-3PAKE falls to unknown key-share attacks by any other client, and undetectable online dictionary attacks by any adversary. The latter attack equally applies to the recently improved S-3PAKE. Indeed, the provable security approach should be taken when designing PAKEs; and furthermore our results highlight that extra cautions still be exercised when defining models and constructing proofs in this direction.     

基于口令的三方认证密钥交换协议

传统的三方认证密钥交换协议不具备前向安全性,难以抵抗不可察觉在线字典攻击。为此,研究简单三方口令认证密钥交换协议,分析其存在的安全漏洞并加以改进,提出一种基于口令的三方认证密钥交换协议。分析结果表明,与其他协议相比,该协议的执行效率和安全性较高。     

An efficient client–client password-based authentication scheme with provable security

Recently, Tso proposed a three-party password-based authenticated key exchange (3PAKE) protocol. This protocol allows two clients to authenticate each other and establish a secure session key through a server over an insecure channel. The main security goals of such protocols are authentication and privacy. However, we show that Tso’s protocol achieves neither authentication goal nor privacy goal. In this paper, we indicate that the privacy and authentication goals of Tso’s protocol will be broken by off-line password guessing attack and impersonation attack, respectively. To overcome the weaknesses, we propose an improved 3PAKE protocol to achieve more security and performance than related protocols. The security of the proposed improved protocol is proved in random oracle model.     

Efficient verifier-based password-authenticated key exchange in the three-party setting

In the last few years, researchers have extensively studied the password-authenticated key exchange (PAKE) in the three-party setting. The fundamental security goal of PAKE is security against dictionary attacks. The protocols for verifier-based PAKE are additionally required to be secure against server compromise. Some verifier-based PAKE schemes in the three-party setting have been suggested to solve the server compromise problem. Unfortunately, the protocols are vulnerable to an off-line dictionary attack. In this paper, we present an efficient verifier-based PAKE protocol for three-parties that is secure against known-key attacks and provides forward secrecy. To the best of our knowledge, the proposed protocol is the first secure three-party verifier-based PAKE protocol in the literature.     

A provably secure and efficient two‐party password‐based explicit authenticated key exchange protocol resistance to password guessing attacks

Password‐based two‐party authenticated key exchange (2PAKE) protocol enables two or more entities, who only share a low‐entropy password between them, to authenticate each other and establish a high‐entropy secret session key. Recently, Zheng et al. proposed a password‐based 2PAKE protocol based on bilinear pairings and claimed that their protocol is secure against the known security attacks. However, in this paper, we indicate that the protocol of Zheng et al. is insecure against the off‐line password guessing attack, which is a serious threat to such protocols. Consequently, we show that an attacker who obtained the users' password by applying the off‐line password guessing attack can easily obtain the secret session key. In addition, the protocol of Zheng et al. does not provide the forward secrecy of the session key. As a remedy, we also improve the protocol of Zheng et al. and prove the security of our enhanced protocol in the random oracle model. The simulation result shows that the execution time of our 2PAKE protocol is less compared with other existing protocols. Copyright © 2015 John Wiley & Sons, Ltd.     

适用于双方频繁通信的密钥交换协议

首先对以前提出的一个高效的基于验证元的三方密钥交换协议进行了安全性分析,指出了它容易受到服务器密钥泄露攻击等安全威胁,且缺乏前向安全性;并以此为基础,针对大多数现存的基于验证元的3PAKE协议均难以抵御服务器密钥泄露攻击的现状,提出了一个新的3PAKE协议。通过安全性分析,证明了新协议比原协议更安全,能够抵御各种已知的攻击,且与现有的大多数同类协议相比具有更高的效率。