Strongly secure identity-based authenticated key agreement protocols

In this paper, we present a strongly secure identity-based (ID-based) two-party authenticated key agreement (AKA) protocol, which captures all basic desirable security properties including master key forward secrecy, ephemeral secrets reveal resistance and so on, and is provably secure in the extended Canetti-Krawczyk (eCK) model. The security of the protocol can be reduced to the standard Computational Bilinear Diffie-Hellman assumption in the random oracle model. Our scheme is secure as long as each party has at least one uncompromised secret. Also, we give a strongly secure variant of the protocol. The variant has a much lower computational overhead than the original scheme, while its security relies on the Gap Bilinear Diffie-Hellman assumption. Currently, there are few ID-based AKA protocols that are provably secure in the strong eCK model. Compared with previous ID-based AKA schemes, our protocols have advantages over them in security or efficiency.     

A novel pairing-free certificateless authenticated key agreement protocol with provable security

Recently, He et al. (Computers and Mathematics with Applications, 2012) proposed an efficient pairing-free certificateless authenticated key agreement (CL-AKA) protocol and claimed their protocol was provably secure in the extended Canetti-Krawczyk (eCK) model. By giving concrete attacks, we indicate that their protocol is not secure in the eCK model. We propose an improved protocol and show our improvement is secure in the eCK model under the gap Diffie-Hellman (GDH) assumption. Furthermore, the proposed protocol is very efficient.     

Strongly secure identity-based authenticated key agreement protocols in the escrow mode

Escrowable identity-based authenticated key agreement(AKA) protocols are desirable under certain circumstances especially in certain closed groups applications.In this paper,we focus on two-party identitybased AKA schemes in the escrow mode,and present a strongly secure escrowable identity-based AKA protocol which captures all basic desirable security properties including perfect forward secrecy,ephemeral secrets reveal resistance and so on.The protocol is provably secure in the extended Canetti-Krawczyk model,and its security can be reduced to the standard computational bilinear Diffie-Hellman assumption in the random oracle model.Assuming no adversary can obtain the master private key for the escrow mode,our scheme is secure as long as each party has at least one uncompromised secret.Also,we present two strongly secure variants of the protocol,which are computationally more efficient than the original scheme.     

强安全的基于身份认证密钥协商协议

LaM acchia等提出了扩展的Canetti-K raw czyk(eCK)安全模型,该模型涵盖了认证密钥协商协议的所有安全特性.鉴于目前大多数基于身份的认证密钥协商协议在eCK模型中是不安全的,利用椭圆曲线加法群构造了一个eCK模型中安全的基于身份认证密钥协商协议.和其它的协议相比,新协议的计算复杂度和通信复杂度较低.新协议提供强安全性,它的安全性证明依赖于随机预言假设和GBDH假设.     

完美前向安全的基于身份认证密钥协商方案

现有的基于身份的一轮认证密钥协商方案没能实现强的完美前向性.采用强不可伪造的签名算法对临时公钥进行签名,提出一种改进的基于身份认证密钥协商方案.首先,对Boneh和Boyen提出的强不可伪造的短签名方案进行改造,提出一种强不可伪造的基于身份签名方案;然后,将新签名方案与Ni等人提出的eCK安全的基于身份一轮认证密钥协商方案相结合,提出新的密钥协商方案.进一步,为了实现新方案的可证明安全性,在对比分析eCK-PFS模型和eCK模型的基础上,融合现有安全模型,定义了基于身份认证密钥协商方案分析的强安全模型ID-eCK-PFS.在ID-eCK-PFS模型下,通过安全性规约,证明了新提出的基于身份认证密钥协商方案实现了强安全性,包括抗密钥泄露伪装、抗临时秘密泄露和完美前向安全性等.     

Provably secure authenticated key exchange protocol under the CDH assumption

Constructing a secure key exchange protocol is one of the most challenging problems in information security. We propose a provably secure two-round two-party authenticated key exchange (2AKE) protocol based on the well-studied CDH assumption in eCK model to provide the strongest definition of security for key exchange protocol when using the matching session to define the partnership. The underlying hardness assumption (CDH assumption) of our protocol is weaker than these of four other provably secure 2AKE protocols in CK model or eCK model and the computational cost of our protocol is reasonable. We also present a three-round variant of our protocol to realize key conformation.     

New identity-based three-party authenticated key agreement protocol with provable security

Key agreement allows multi-parties exchanging public information to create a common secret key that is known only to those entities over an insecure network. In the recent years, several identity-based (ID-based) authenticated key agreement protocols have been proposed and most of them broken. In this paper, we formalize the security model of ID-based authenticated tripartite key agreement protocol and propose a provably secure ID-based authenticated key agreement protocol for three parties with formal security proof under the computational Diffie–Hellman assumption. Experimental results by using the AVISPA tool show that the proposed protocol is secure against various malicious attacks.     

一种基于NTRU新型认证密钥协商协议的设计

NTRU是目前最实用的基于格构造的密码体制,然而相对于基于NTRU的加密、签名方案,其密钥协商协议却一直很少见诸文献。针对这一问题,提出了一种基于NTRU格的认证密钥协商协议。在随机预言机模型下,该方案是eCK模型中可证明安全,并且可以抵抗中间人攻击、重放攻击、冒充攻击、达到弱完美前向安全;与传统的DH、ECDH等方案相比,该方案计算效率更高,同时因其安全性可以规约到基于格中最短向量困难问题,可以抗量子攻击。     

Security weaknesses of a signature scheme and authenticated key agreement protocols

At ACISP 2012, a novel deterministic identity-based (aggregate) signature scheme was proposed that does not rely on bilinear pairing. The scheme was formally proven to be existentially unforgeable under an adaptive chosen message and identity attack. The security was proven under the strong RSA assumption in the random oracle model. In this paper, unfortunately, we show that the signature scheme is universally forgeable, i.e., an adversary can recover the private key of a user and use it to generate forged signatures on any messages of its choice having on average eight genuine signatures. This means, that realizing a deterministic identity-based signature scheme in composite order groups is still an open problem. In addition, we show that a preliminary version of the authenticated key exchange protocol proposed by Okamoto in his invited talk at ASIACRYPT 2007 is vulnerable to the key-compromise impersonation attack and therefore cannot be secure in the eCK model. We also show that the two-party identity-based key agreement protocol of Hölbl et al. is vulnerable to the unknown key-share attack.     

构建无证书的两方认证密钥协商协议

基于无证书的认证密钥协商方案相比基于PKI的方案具有身份管理的简单性,同时相比基于身份的方案具有无密钥托管性。基于可证安全的无证书加密方案提出了一个两方认证密钥协商方案.通过与其他方案在安全性和有效性方面的比较,该方案满足更多的安全属性要求,如完美前向安全性,PKG前向安全性,已知会话相关临时秘密信息安全性和无密钥托管等安全特性,同时具有良好的计算有效性。     

A Provable Secure ID-Based Explicit Authenticated Key Agreement Protocol Without Random Oracles

In this paper, we present an identity-based explicit authenticated key agreement protocol that is provably secure without random oracles. The protocol employs a new method to isolate a session key from key confirmation keys so that there is no direct usage of hash functions in the protocol. The protocol is proved secure without random oracles in a variant of Bellare and Rogaway style model, an exception to current proof method in this style model in the ID-based setting. We believe that this key isolation method is novel and can be further studied for constructing more effcient protocols.     

Provably secure three-party password-based authenticated key exchange protocol

A three-party password-based authenticated key exchange (3PAKE) protocol is a useful mechanism to establish a secure session key in a network. However, most current 3PAKE protocols only achieve “heuristic” security; the underlying hardness assumptions of these protocols are not perfect. We propose a 3PAKE protocol which is provably secure if the Diffie–Hellman problem is computationally infeasible (the CDH assumption), even in the 3eCK model where the adversary is allowed to make more queries and have more freedom than previous models. In our formal proof, we use the trapdoor test technique introduced by Cash, Kiltz and Shoup to construct an efficient decision oracle. As far as we know, our protocol is the first provably secure 3PAKE protocol based on the CDH assumption and the first 3PAKE protocol using the trapdoor test technique for the security proof.     

改进的双方密钥协商协议

双方认证密钥协商是生成会话密钥的重要手段。分析了赵建杰等于2011年提出的一个可证明安全的双方认证密钥协商协议,指出如果敌手持有原协议的长期私钥,协议是不安全的。提出一种改进的协议,新协议将影响安全性的公开参数保护起来,避免了长期私钥的泄露,并对新协议的安全性和计算量进行了讨论。分析结果表明,新协议在减少计算量的前提下实现了协议双方的安全密钥协商。     

A strongly secure pairing-free certificateless authenticated key agreement protocol under the CDH assumption基于CDH假设的强安全的无对的无证书认证密钥协商协议

Certificateless authenticated key agreement (CL-AKA) protocols have been studied a great deal since they neither suffer from a heavy certificate management burden nor have the key escrow problem. Recently, many efficient CL-AKA protocols without pairings have been built. However, these pairing-free CL-AKA protocols are either not proved in any formal security model or proved under the gap Diffie-Hellman (GDH) assumption, a non-standard and strong assumption. With available implementation technologies, pairings are needed to realize the GDH assumption, which means that these pairing-free CL-AKA protocols are not pure pairing-free. Furthermore, these protocols are insecure in the strengthened eCK (seCK) model, which encompasses the eCK model and considers leakages on intermediate results. In this paper, we present a pure pairing-free CL-AKA protocol, which is provably secure in the seCK model under the standard computational Diffie-Hellman (CDH) assumption. Compared with the existing CL-AKA protocols, the proposed protocol has advantage over them in security or efficiency.     

Certificateless and identity-based authenticated asymmetric group key agreement

Group key agreement (GKA) is one of the traditional ways to guarantee the subsequent secure group communications. However, conventional GKA protocols face two limitations, i.e., they require two or more rounds to establish secure channels and are sender restricted. Asymmetric group key agreement (AGKA) eliminates above two limitations of GKA. It allows a group of users to establish a public group encryption key and a different secret decryption key of each group member in one round. Any user who knows the group encryption key can encrypt to the group members. This paper studies authenticated AGKA in certificateless and identity-based public key cryptosystems. We formalize the security model of certificateless authenticated asymmetric group key agreement and realize a one-round certificateless authenticated asymmetric group key agreement protocol to resist active attacks in the real world. We also investigate the relation between certificateless authenticated AGKA and identity-based authenticated AGKA. We propose a concrete conversion from certificateless authenticated AGKA to session key escrow-free identity-based authenticated AGKA.     

可信计算环境下基于TPM的认证密钥协商协议

基于身份的认证密钥协商协议存在密钥托管、ID管理、ID唯一性和私钥的安全分发等问题,目前的可信计算技术为此提供了很好的解决方案。利用TPM平台中EK和tpmproof唯一性的特点,结合McCullagh-Barreto认证密钥协商协议思想,提出了一个在可信计算环境下基于TPM的认证密钥协商协议,该协议较好地解决了上述基于身份的密钥协商协议所存在的问题。用CK模型对所提协议进行了安全性分析,结果表明该协议具备已知密钥安全性,完善前向保密性及密钥泄露安全性等CK安全模型下相应的安全属性。     

标准模型下可证安全的身份基认证密钥协商协议

提出一个在标准模型下可证安全的双方身份基密钥协商协议.新协议的设计思想来源于Gentry的身份基加密方案.提出的新协议可工作于托管或者无托管两种模式.在标准模型下(即不利用随机预言假设),文中给出了该协议的安全性证明.新提出的协议与目前现有仅在随机预言模型中证明安全的协议相比,在计算和通信效率方面相当.     

基于身份可证安全的双方密钥协商协议*

针对双方认证和密钥协商协议中会话双方属于不同密钥产生中心的情况,利用双线性对性质和BDH假设,基于可证安全的eCK模型提出一种基于身份可证安全的双方密钥协商协议。该协议从测试会话在随机谕示模型中是否存在相应的匹配会话两个方面,对提出的协议方案进行了安全性证明：若BDH假设不可解,则本方案是安全的认证密钥协商协议。     

Efficient and provably secure password-based group key agreement protocol

This paper considers the issue on authenticated group key agreement protocol among n users broadcasting communication over an insecure public network. Many authenticated group Diffie-Hellman key agreement protocols have been proposed to meet the challenges. However, existing protocols are either limited by the use of public key infrastructure or by their scalability, requiring O(n) rounds. To overcome these disadvantages, we propose an efficient password-based group key agreement protocol resistant to the dictionary attacks by adding password-authentication services to a non-authenticated multi-party key agreement protocol proposed by Horng. The proposed protocol is very efficient since it only requires constant rounds to agree upon a session key, and each user broadcasts a constant number of messages and only requires four exponentiations. Under the Decisional Diffie-Hellman assumption, we will show the proposed protocol is provably secure in both the ideal-cipher model and the random-oracle model.