Multiparty quantum key agreement with single particles

Two conditions must be satisfied in a secure quantum key agreement (QKA) protocol: (1) outside eavesdroppers cannot gain the generated key without introducing any error; (2) the generated key cannot be determined by any non-trivial subset of the participants. That is, a secure QKA protocol can not only prevent the outside attackers from stealing the key, but also resist the attack from inside participants, i.e. some dishonest participants determine the key alone by illegal means. How to resist participant attack is an aporia in the design of QKA protocols, especially the multi-party ones. In this paper we present the first secure multiparty QKA protocol against both outside and participant attacks. Further more, we have proved its security in detail.     

Cryptanalysis of tripartite and multi-party authenticated key agreement protocols

Al-Riyami and Paterson proposed four authenticated tripartite key agreement protocols which make use of the Weil pairing. Recently, Lee et al. extended the protocols to a multi-party setting assuming the existence of cryptographic multilinear forms. In this paper we show that the tripartite and multi-party authenticated key agreement protocols are insecure against several active attacks.     

Cryptanalysis of a multiparty quantum key agreement protocol based on commutative encryption

Recently, Sun et al. (Quantum Inf Process 15(5):2101–2111, 2016) proposed an efficient multiparty quantum key agreement protocol based on commutative encryption. The aim of this protocol is to negotiate a secret shared key among multiple parties with high qubit efficiency as well as security against inside and outside attackers. The shared key is the exclusive-OR of all participants’ secret keys. This is achieved by applying the rotation operation on encrypted photons. For retrieving the final secret key, only measurement on single states is needed. Sun et al. claimed that assuming no mutual trust between participants, the scheme is secure against participant’s attack. In this paper, we show that this is not true. In particular, we demonstrate how a malicious participant in Sun et al.’s protocol can introduce “a” final fake key to target parties of his choice. We further propose an improvement to guard against this attack.     

TTS组密钥协商协议的安全性分析与改进

针对动态对等通信中的组密钥协商协议进行了分析和研究,指出王志伟等人提出的基于树结构和门限思想的组密钥协商协议（TTS）存在密钥控制和不等献性等缺陷,进而给出了一个改进的方案（I-TTS）。安全性分析表明,I-TTS协议不仅克服了TTS协议中的前向安全性和密钥控制缺陷,还满足等献性。     

基于三角矩阵的密钥协商协议的密码学分析

密钥协商是实现参与者在公平的开放环境下建立会话密钥的重要手段。最近,Alvarez等人提出了一种新的密钥协商协议,该协议的会话密钥是通过分块上三角矩阵的幂乘得到的。但研究发现,该协议并不安全,其安全参数可以简单地通过计算一个方程组来获得。详细分析了该协议,并提出了一种切实可行的攻击方法,而且该方法可以推广到使用类似技术设计的密钥协商协议中。     

Multi-party quantum key agreement protocol secure against collusion attacks

The fairness of a secure multi-party quantum key agreement (MQKA) protocol requires that all involved parties are entirely peer entities and can equally influence the outcome of the protocol to establish a shared key wherein no one can decide the shared key alone. However, it is found that parts of the existing MQKA protocols are sensitive to collusion attacks, i.e., some of the dishonest participants can collaborate to predetermine the final key without being detected. In this paper, a multi-party QKA protocol resisting collusion attacks is proposed. Different from previous QKA protocol resisting \(N-1\) coconspirators or resisting 1 coconspirators, we investigate the general circle-type MQKA protocol which can be secure against t dishonest participants’ cooperation. Here, \(t < N\). We hope the results of the presented paper will be helpful for further research on fair MQKA protocols.     

基于身份的可认证多方密钥协商新方案

认证密钥协商协议允许通信方在公开的网络环境里进行认证,并协商一个安全的共享会话密钥。在McCullagh-Barreto方案的基础上,提出了一个基于身份的可认证多方密钥协商新方案。引入密钥种子更新临时公私钥对,实现了认证功能,提高了安全性,成功抵抗了Reveal查询攻击和密钥泄漏扮演攻击,且具有无密钥控制、等献性等特性。     

Rational protocol of quantum secure multi-party computation

In a rational protocol, players are supposed to be rational, rather than honest, semi-honest or dishonest. This kind of protocols is practical and important, but seldom researched in quantum computation field. In this paper, a multifunctional rational quantum secure multi-party computation protocol is investigated. Firstly, a rational quantum summation protocol is proposed. Secondly, the protocol is generalized to a rational quantum multi-party computation protocol. The computation which is homomorphic can be resolved by our protocol. Thirdly, from the view of utilities, correctness, Nash equilibrium and fairness, analyses show that our protocol is rational. Besides, our protocol is also proved to be secure, efficient and practical. Our research will promote the development of rational quantum multi-party protocol.     

Efficient multiparty quantum key agreement protocol based on commutative encryption

A secure multiparty quantum key agreement protocol using single-qubit states is proposed. The agreement key is computed by performing exclusive-OR operation on all the participants’ secret keys. Based on the commutative property of the commutative encryption, the exclusive-OR operation can be performed on the plaintext in the encrypted state without decrypting it. Thus, it not only protects the final shared key, but also reduces the complexity of the computation. The efficiency of the proposed protocol, compared with previous multiparty QKA protocols, is also improved. In the presented protocol, entanglement states, joint measurement and even the unitary operations are not needed, and only rotation operations and single-state measurement are required, which are easier to be realized with current technology.     

一种匿名认证密钥协商协议*

大多数的认证密钥协商协议没有考虑用户的匿名性,在分析已有MAKAP协议的基础上,提出了一种具有用户匿名性的认证密钥协商协议AKAPA,为用户提供隐私保护。在随机预言机模型下证明其安全性,并就增强的安全属性进行了分析,表明AKAPA具有完美前向安全性,能够抗未知共享密钥攻击和完善拒绝服务攻击等。性能分析表明效率优于已有协议,具有较高的实用性。     

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.     

Authenticating tripartite key agreement protocol with pairings

In this paper, an authenticated tripartite key agreement protocol is proposed, which is an ID-based one with pairings. This protocol involves only one round. The authenticity of the protocol is assured by a special signature scheme, so that messages carrying the information of two ephemeral keys can be broadcasted authentically by an entity. Consequently, one instance of the protocol results in eight session keys for three entities. In other word, one instance of the protocol generates a session key, which is eight times longer than those obtained from traditional key agreement protocols. Security attributes of the protocol are presented, and the computational overhead and bandwidth of the broadcast messages are analyzed as well.     

具有混合安全的认证密钥协商协议

基于切比雪夫映射的半群特性和经典的RSA算法,提出了一种具有混合安全的密钥协商协议.新协议使用RSA算法来保护切比雪夫多项式,从而避免了Bergamo攻击.理论分析表明,新协议不仅具有强安全特性,而且还具有高效性.     

A cost-effective quantum protocol for secure multi-party multiplication

Quantum Information Processing - Ground-state cooling of multiple mechanical resonators is an important goal in the study of quantum optomechanics. Here, we propose a dynamic dissipative...     

可认证的无证书密钥协商协议

无证书公钥密码体制能有效地克服基于身份密码体制中密钥托管的限制,结合基于身份密码体制和可认证密钥协商的优点,提出了一个新的可认证无证书密钥协商协议。经过分析,该协议不仅满足一般密钥协商的安全特性,而且与已有的密钥协商相比,具有更少的对数运算。     

Multiparty quantum key agreement protocol based on locally indistinguishable orthogonal product states

Based on locally indistinguishable orthogonal product states, we propose a novel multiparty quantum key agreement (QKA) protocol. In this protocol, the private key information of each party is encoded as some orthogonal product states that cannot be perfectly distinguished by local operations and classical communications. To ensure the security of the protocol with small amount of decoy particles, the different particles of each product state are transmitted separately. This protocol not only can make each participant fairly negotiate a shared key, but also can avoid information leakage in the maximum extent. We give a detailed security proof of this protocol. From comparison result with the existing QKA protocols, we can know that the new protocol is more efficient.     

Cryptanalysis and improvement of a quantum private set intersection protocol

A recent Quantum Private Set Intersection (QPSI) scheme is crypt-analyzed. The original claimed communication overhead is shown to be not accurate. And the original security definition is passive and not fair. To ensure fairness, a passive third party is introduced. It is also shown that unconditional fairness of QPSI protocol is impossible. Since otherwise, it would violate a well-known impossible quantum cryptography result.     

A conference key agreement protocol with fault-tolerant capability

Secure communication is of utmost importance to participants of Internet conferences. Secure communication thwarts eavesdropping. In an Internet conference, all conference participants together establish a common conference key to enable multi-party and secure exchange of messages. However, malicious conference participants may try to obtain the conference key through unfair means, and this could result in the generation of different conference keys. This paper is intended as a proposal of a new form of conference key agreement protocol. It emphasizes the filtering of malicious participants at the beginning of the conference to ensure that all participants obtain the same conference key. The proposed method also has fault-tolerant capability. Efficiency and security of a protocol is important in practice. The security of the proposed protocol is based on discrete logarithm problem assumption. The protocol is executed in computationally secure environment. The secret information of a user cannot be determined from its corresponding public information and therefore ensures privacy. Since efficiency of a protocol depends on low computation cost, the protocol attempts to achieve lower computation cost without compromising on security.     

一个基于身份的密钥隔离认证密钥协商协议

鉴于目前已有的基于身份的认证密钥协商协议都未考虑后向安全性,结合密钥进化的思想,利用椭圆曲线加法群提出了一个基于身份的密钥隔离认证密钥协商协议.协议去除了双线性对运算,效率比基于双线性对构造的基于身份的协议有较大提高;协议不仅满足目前已知的所有针对认证密钥协商协议的安全性要求,而且还满足后向安全性.