An efficient pairing‐free identity‐based authenticated group key agreement protocol

An authenticated group key agreement protocol allows participants to agree on a group key that will be subsequently used to provide secure group communication over an insecure network. In this paper, we give a security analysis on a pairing‐free identity‐based authenticated group key agreement because of Islam et al. We show that the protocol of Islam et al. cannot satisfy the minimal security requirements of the key agreement protocols. We propose an efficient pairing‐free identity‐based authenticated group key agreement for imbalanced mobile network. The proposed protocol can be implemented easily for practical application in mobile networks as it is free from bilinear. Under the difficulty of the InvCDH and CDH we demonstrate that the proposed protocol provides perfect forward secrecy, implicit key authentication and the dynamic functionality. As compared with the group key agreement protocols for imbalanced mobile network, the proposed protocol provides stronger security properties and high efficiency. Copyright © 2013 John Wiley & Sons, Ltd.     

Improvement of McCullagh-Barreto key agreement with KCI-security

McCullagh-Barreto key agreement protocol and its variant achieve perfect forward security and key generation center (KGC) forward security, but provide no resistance to key compromise impersonation attack (KCI attack). In this paper, we give a formal treatment of key compromise impersonation (KCI) attack and define the security notion against it. Then an variant of McCullagh-Barreto protocol is presented with only one more Hash operation. The improved protocol preserves perfect forward security and KGC forward security, and furthermore is proved to be secure against KCI attack under k-Gap-BCAA1 assumption.     

Cryptanalysis of smart‐card‐based password authenticated key agreement protocol for session initiation protocol of Zhang et al.

As the core signaling protocol for multimedia services, such as voice over internet protocol, the session initiation protocol (SIP) is receiving much attention and its security is becoming increasingly important. It is critical to develop a roust user authentication protocol for SIP. The original authentication protocol is not strong enough to provide acceptable security level, and a number of authentication protocols have been proposed to strengthen the security. Recently, Zhang et al. proposed an efficient and flexible smart‐card‐based password authenticated key agreement protocol for SIP. They claimed that the protocol enjoys many unique properties and can withstand various attacks. However, we demonstrate that the scheme by Zhang et al. is insecure against the malicious insider impersonation attack. Specifically, a malicious user can impersonate other users registered with the same server. We also proposed an effective fix to remedy the flaw, which remedies the security flaw without sacrificing the efficiency. The lesson learned is that the authenticators must be closely coupled with the identity, and we should prevent the identity from being separated from the authenticators in the future design of two‐factor authentication protocols. Copyright © 2014 John Wiley & Sons, Ltd.     

AN IMPROVED AUTHENTICATED KEY AGREEMENT PROTOCOL

In 1999, Seo and Sweeney proposed a simple authenticated key agreement protocol that was designed to act as a Diffie-Hellman key agreement protocol with user authentication. Various attacks on this protocol are described and enhanced in the literature. Recently, Ku and Wang proposed an improved authenticated key agreement protocol, where they asserted the protocol could withstand the existing attacks. This paper shows that Ku and Wang＇s protocol is still vulnerable to the modification attack and presents an improved authenticated key agreement protocol to enhance the security of Ku and Wang＇s protocol. The protocol has more efficient performance by replacing exponentiation operations with message authentication code operations.     

A chaotic map‐based anonymous multi‐server authenticated key agreement protocol using smart card

Authenticated key agreement protocols play an important role for network‐connected servers to authenticate remote users in Internet environment. In recent years, several authenticated key agreement protocols for single‐server environment have been developed based on chaotic maps. In modern societies, people usually have to access multiple websites or enterprise servers to accomplish their daily personal matters or duties on work; therefore, how to increase user's convenience by offering multi‐server authentication protocol becomes a practical research topic. In this study, a novel chaotic map‐based anonymous multi‐server authenticated key agreement protocol using smart card is proposed. In this protocol, a legal user can access multiple servers using only a single secret key obtained from a trusted third party, known as the registration center. Security analysis shows this protocol is secure against well‐known attacks. In addition, protocol efficiency analysis is conducted by comparing the proposed protocol with two recently proposed schemes in terms of computational cost during one authentication session. We have shown that the proposed protocol is twice faster than the one proposed by Khan and He while preserving the same security properties as their protocol has. Copyright © 2014 John Wiley & Sons, Ltd.     

An ID‐based mutual authentication with key agreement protocol for multiserver environment on elliptic curve cryptosystem

Mutual authentication is used to validate the legitimacy of a remote login user and a server. Conventional user authentication protocols are suited to solve the privacy and security problems for the single client/server architecture environment. However, the use of computer networks and information technology has grown spectacularly. More and more network architectures are used in multi‐server environments. Recently, several authentication schemes for multi‐server environments have been proposed. However, the performance of these schemes is not suitable for applications. To improve the performance, we propose a new ID‐based mutual authentication protocols for multi‐server environment without bilinear pairings. We also show that the proposed scheme is provable secure in the random oracle model. Copyright © 2012 John Wiley & Sons, Ltd.     

一种自证明身份密钥协商协议的研究

针对Diffie-Hellman密钥协商协议易受中间人（man in the middle）攻击的问题，提出了一种自证明身份的密钥协商协议，阐述了密钥交换原理，分析了其安全性和实现的关键技术。该协议将RSA与离散对数相结合，使通信双方在不需对方公开密钥证书，不需数字签名，也不需密钥分配中心（KDC）的条件下进行双向身份认证，并同时产生共享的会话密钥，具有一定实用价值。     

Smart card–based password authenticated key agreement protocol using chaotic maps

In 2015, Lee proposed time stamp–based and nonce‐based password authenticated key agreement protocols based on the Chebyshev chaotic map to enhance the security of relevant schemes. However, in this paper, we demonstrate that Lee's protocols are vulnerable to user impersonation and stolen verifier attacks. To overcome these security problems, we thus provide an improved version using a smart card. Security analysis and comparisons show that the proposed protocol is more secure and maintains better performance. Furthermore, we perform a formal verification of the proposed protocol using the widely accepted AVISPA tool for error detection.     

Cryptanalysis of an efficient three‐party password‐based key exchange scheme

Three‐party password‐authenticated key exchange (3PAKE) protocols allow entities to negotiate a secret session key with the aid of a trusted server with whom they share a human‐memorable password. Recently, Lou and Huang proposed a simple 3PAKE protocol based on elliptic curve cryptography, which is claimed to be secure and to provide superior efficiency when compared with similar‐purpose solutions. In this paper, however, we show that the solution is vulnerable to key‐compromise impersonation and offline password guessing attacks from system insiders or outsiders, which indicates that the empirical approach used to evaluate the scheme's security is flawed. These results highlight the need of employing provable security approaches when designing and analyzing PAKE schemes. Copyright © 2011 John Wiley & Sons, Ltd.     

A pairing‐free certificateless authenticated key agreement protocol

Many certificateless two‐party authenticated key agreement schemes using bilinear pairings have been proposed. But the relative computation cost of the pairing is approximately twenty times higher than that of the scalar multiplication over elliptic curve group In order to improve the performance we propose a certificateless two‐party authenticated key agreement scheme without bilinear pairings in this paper. A security proof under random oracle model is also provided. Copyright © 2011 John Wiley & Sons, Ltd.     

A fault‐tolerant group key agreement protocol exploiting dynamic setting

A fault‐tolerant group key agreement is an essential infrastructure for Internet communication among all involved participants; it can establish a secure session key no matter how many malicious participants exit simultaneously in an effort to disrupt the key agreement process. Recently, Zhao et al. proposed an efficient fault‐tolerant group key agreement protocol named efficient group key agreement that can resist denial‐of‐service attacks, reply attacks, man‐in‐middle attacks, and common modulus attacks; it can also preserve forward secrecy with lower computational cost than previous protocols. We show that it is still vulnerable to active attacks by malicious participants and modify the corresponding security weakness adaptively. Furthermore, we propose an efficient fault‐tolerant group key agreement based on a binary tree structure and enhance it to a dynamic setting where participants can leave or join the group arbitrarily according to their preferences with instant session key refreshment. Additionally, our session key refreshment is based on secure key updating to protect forward/backward confidentiality and is resistant to active/passive attacks. The performance analysis shows that our proposed protocol has lower computational cost and little additional communication cost exploiting dynamic setting. Copyright © 2013 John Wiley & Sons, Ltd.     

An efficient hash-based authenticated key agreement scheme for multi-server architecture resilient to key compromise impersonation

During the past decade, rapid advances in wireless communication technologies have made it possible for users to access desired services using hand-held devices. Service providers have hosted multiple servers to ensure seamless online services to end-users. To ensure the security of this online communication, researchers have proposed several multi-server authentication schemes incorporating various cryptographic primitives. Due to the low power and computational capacities of mobile devices, the hash-based multi-server authenticated key agreement schemes with offline Registration Server (RS) are the most efficient choice. Recently, Kumar-Om presented such a scheme and proved its security against all renowned attacks. However, we find that their scheme bears an incorrect login phase, and is unsafe to the trace attack, the Session-Specific Temporary Information Attack (SSTIA), and the Key Compromise Impersonation Attack (KCIA). In fact, all of the existing multi-server authentication schemes (hash-based with offline RS) do not withstand KCIA. To deal with this situation, we propose an improved hash-based multi-server authentication scheme (with offline RS). We analyze the security of the proposed scheme under the random oracle model and use the ‘‘Automated Validation of Internet Security Protocols and Applications’’ (AVISPA) tool. The comparative analysis of communication overhead and computational complexity metrics shows the efficiency of the proposed scheme.     

Cryptanalysis and improvement of a three‐party password‐based authenticated key exchange protocol with user anonymity using extended chaotic maps

Three‐party password‐authenticated key exchange (3PAKE) protocols allow two clients to agree on a secret session key through a server via a public channel. 3PAKE protocols have been designed using different arithmetic aspects including chaotic maps. Recently, Lee et al. proposed a 3PAKE protocol using Chebyshev chaotic maps and claimed that their protocol has low computation and communication cost and can also resist against numerous attacks. However, this paper shows that in spite of the computation and communication efficiency of the Lee et al. protocol, it is not secure against the modification attack. To conquer this security weakness, we propose a simple countermeasure, which maintains the computation and communication efficiency of the Lee et al. protocol. Copyright © 2014 John Wiley & Sons, Ltd.     

Cryptanalysis and improvement of the YAK protocol with formal security proof and security verification via Scyther

Hao proposed the YAK as a robust key agreement based on public‐key authentication, and the author claimed that the YAK protocol withstands all known attacks and therefore is secure against an extremely strong adversary. However, Toorani showed the security flaws in the YAK protocol. This paper shows that the YAK protocol cannot withstand the known key security attack, and its consequences lead us to introduce a new key compromise impersonation attack, where an adversary is allowed to reveal both the shared static secret key between two‐party participation and the ephemeral private key of the initiator party in order to mount this attack. In addition, we present a new security model that covers these attacks against an extremely strong adversary. Moreover, we propose an improved YAK protocol to remedy these attacks and the previous attacks mentioned by Toorani on the YAK protocol, and the proposed protocol uses a verification mechanism in its block design that provides entity authentication and key confirmation. Meanwhile, we show that the proposed protocol is secure in the proposed formal security model under the gap Diffie‐Hellman assumption and the random oracle assumption. Moreover, we verify the security of the proposed protocol and YAK protocol by using an automatic verification method such as the Scyther tool, and the verification result shows that the security claims of the proposed protocol are proven, in contrast to those of the YAK protocol, which are not proven. The security and performance comparisons show that the improved YAK protocol outperforms previous related protocols.     

改进的3G认证与密钥分配协议

本文详细分析了3G认证与密钥分配协议的过程以及协议的安全性，找出了协议中的安全缺陷，并给出了攻击者可能进行的攻击。针对协议的安全漏洞，提出了一种改进的认证与密钥分配方案，解决了对VLR的认证以及网络端信息传输的安全性。最后，对改进方案的安全性进行了分析。     

Cryptanalysis and security enhancement of a robust two‐factor authentication and key agreement protocol

Two‐factor user authentication scheme allows a user to use a smart card and a password to achieve mutual authentication and establish a session key between a server and a user. In 2012, Chen et al. showed that the scheme of Sood et al. does not achieve mutual authentication and is vulnerable to off‐line password guessing and smart card stolen attacks. They also found that another scheme proposed by Song is vulnerable to similar off‐line password guessing and smart card stolen attacks. They further proposed an improved scheme. In this paper, we first show that the improved scheme of Chen et al. still suffers from off‐line password guessing and smart card stolen attacks, does not support perfect forward secrecy, and lacks the fairness of session key establishment. We then propose a new security‐enhanced scheme and show its security and authentication using the formal verification tool ProVerif, which is based on applied pi calculus. Copyright © 2014 John Wiley & Sons, Ltd.     

VANET系统中基于中国剩余定理的群内相互认证密钥协商协议

针对车载自组网(VANET)系统中车辆在公开网络上相互通信容易受到恶意攻击的问题,提出一种VANET系统中群内相互认证密钥协商协议.利用中国剩余定理建立动态车辆群,以适应VANET拓扑的快速变化.通信双方利用签名信息快速认证消息发送方的身份,并通过切比雪夫混沌映射的半群性进行密钥协商.采用假名更新和私钥更新机制,保护车...     

Strongly secure ID‐based authenticated key agreement protocol for mobile multi‐server environments

To provide mutual authentication and communication confidentiality between mobile clients and servers, numerous identity‐based authenticated key agreement (ID‐AKA) protocols were proposed to authenticate each other while constructing a common session key. In most of the existing ID‐AKA protocols, ephemeral secrets (random values) are involved in the computations of the common session key between mobile client and server. Thus, these ID‐AKA protocols might become vulnerable because of the ephemeral‐secret‐leakage (ESL) attacks in the sense that if the involved ephemeral secrets are compromised, an adversary could compute session keys and reveal the private keys of participants in an AKA protocol. Very recently, 2 ID‐AKA protocols were proposed to withstand the ESL attacks. One of them is suitable for single server environment and requires no pairing operations on the mobile client side. The other one fits multi‐server environments, but requires 2 expensive pairing operations. In this article, we present a strongly secure ID‐AKA protocol resisting ESL attacks under mobile multi‐server environments. By performance analysis and comparisons, we demonstrate that our protocol requires the lowest communication overhead, does not require any pairing operations, and is well suitable for mobile devices with limited computing capability. For security analysis, our protocol is provably secure under the computational Diffie‐Hellman assumption in the random oracle model.     

Cryptanalysis and enhancements of efficient three‐party password‐based key exchange scheme

In this paper, we first showed that Lou and Huang's three‐party password‐based key exchange protocol is still vulnerable to offline dictionary attacks. Thereafter, we proposed an enhanced protocol that can defeat the attack described and yet is efficient. Finally, we provided the rigorous proof of the security for it. Copyright © 2011 John Wiley & Sons, Ltd.