Group key agreement protocols allow a group of users, communicating over a public network, to establish a shared secret key to achieve a cryptographic goal. Protocols based on certificateless public key cryptography (CL-PKC) are preferred since CL-PKC does not need certificates to guarantee the authenticity of public keys and does not suffer from key escrow of identity-based cryptography. Most previous certificateless group key agreement protocols deploy signature schemes to achieve authentication and do not have constant rounds. No security model has been presented for group key agreement protocols based on CL-PKC. This paper presents a security model for a certificateless group key agreement protocol and proposes a constant-round group key agreement pro- tocol based on CL-PKC. The proposed protocol does not involve any signature scheme, which increases the efficiency of the protocol. It is formally proven that the proposed protocol provides strong AKE-security and tolerates up to n-2 malicious insiders for weak MA-security. The protocol also resists key control attack under a weak corruption model.
Group key agreement protocols allow a group of users, communicating over a public network, to establish a shared secret key to achieve a cryptographic goal. Protocols based on certificateless public key cryptography (CL-PKC) are preferred since CL-PKC does not need certificates to guarantee the authenticity of public keys and does not suffer from key escrow of identity-based cryptography. Most previous certificateless group key agreement protocols deploy signature schemes to achieve authentication and do not have constant rounds. No security model has been presented for group key agreement protocols based on CL-PKC. This paper presents a security model for a certificateless group key agreement protocol and proposes a constant-round group key agreement pro- tocol based on CL-PKC. The proposed protocol does not involve any signature scheme, which increases the efficiency of the protocol. It is formally proven that the proposed protocol provides strong AKE-security and tolerates up to n-2 malicious insiders for weak MA-security. The protocol also resists key control attack under a weak corruption model.
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.
Authenticated key agreement protocol is one of the important cryptographic primitives to ensure secure communication in an open network. Certificateless public key cryptography (CL-PKC) represents an interesting and potentially useful balance between public key cryptography based on certificates and identity-based cryptography. The topic of CL-PKC has undergone quite rapid development with schemes being proposed for encryption and signatures, while certificateless authenticated key agreement protocols are seldom discussed. In this paper, we present a secure two-party authenticated key agreement protocol based on an efficient certificateless public key encryption with pairing. Such a scheme achieves almost all of the security attributes, including known-key secrecy, perfect forward secrecy, PKG forward secrecy, key-compromise impersonation resilience, unknown key-share resilience, known session-specific temporary information security, message independence and no key control. Meanwhile, it is also practical with nice efficiency.
Key agreement protocols are multi-party protocols in which entities exchange public information allowing them to create a common secret key that is known only to those entities and which cannot be predetermined by any party. Key agreement can be achieved using a public key infrastructure or identity-based cryptography. However, the former suffers from a heavy certificate management burden, while the latter is subject to the so-called key escrow problem. Recently, the notion of certificateless public key cryptography (CL-PKC) was introduced to mitigate these limitations. In this paper, we introduce the notion of three-party authenticated key agreement into CL-PKC and propose a concrete certificateless three-party authenticated key agreement protocol. We show that the proposed protocol is secure (i.e. conforms to defined security attributes) while being efficient.
Authenticated key agreement (AK) protocol is crucial in providing data confidentiality and integrity for subsequent communications among two or more parties over a public network. Certificateless public key cryptography (CL-PKC) combines the advantage of the identity-based public key cryptography (ID-PKC) and the traditional public key cryptography (PKC). Unfortunately, construction of CL-PKC and AK protocols has so far depended on the use of identity-based encryption, which results in the bilinear pairing-based schemes that need costly operations. We present a secure certificateless authenticated key agreement protocol without paring, based on the certificateless encryption scheme proposed by J. Baek et al. It shows that the newly proposed scheme is of nice efficiency and practical. Moreover, it provides perfect forward secrecy, PKG forward secrecy and almost all the other known security attributes, such as known-key secrecy, key-compromise impersonation resilience, unknown key-share resilience, known session-specific temporary information security, message independence and no key control.
With the development of multiuser online meetings, more group-oriented technologies and applications for instance collaborative work are becoming increasingly important.Authenticated Group Key Agreement (AGKA) schemes provide a shared group key for users with after their identities are confirmed to guarantee the confidentiality and integrity of group communications.On the basis of the Public Key Cryptography (PKC) system used, AGKA can be classified as Public Key Infrastructure-based, Identity-based, and Certificateless.Because the latter type can solve the certificate management overhead and the key escrow problems of the first two types, Certificateless-AGKA (CL-AGKA) protocols have become a popular area of research.However, most CL-AGKA protocols are vulnerable to Public Key Replacement Attacks (PKRA) due to the lack of public key authentication.In the present work, we present a CL-AGKA scheme that can resist PKRA in order to solve impersonation attacks caused by those attacks.Beyond security, improving scheme efficiency is another direction for AGKA research.To reduce the communication and computation cost, we present a scheme with only one round of information interaction and construct a CL-AGKA scheme replacing the bilinear pairing with elliptic curve cryptography.Therefore, our scheme has good applicability to communication environments with limited bandwidth and computing capabilities.
We present an efficient authenticated group key agreement (AGKA) protocol in certificateless public key setting (CL-AGKA). The protocol only needs two communication rounds. In each protocol run, only four pairing computations are involved for each participant. The authentication in our protocol is realized using a signature scheme which is provably secure in the strongest security model for certificateless signature (CLS) schemes where the type I/II adversary is a super type I/II adversary. The security analysis shows our protocol satisfies Key authentication, Known session key security, Key compromise impersonation security, Perfect forward security, and Known session-specific temporary information security.