Certificateless public key cryptography (CL-PKC) is a new paradigm in public key cryptography which avoids the inherent key escrow problem of identity-based public key cryptography (ID-PKC) and yet requires no certificates to guarantee the authenticity of users' public keys. It was first introduced by Al-Riyami and Paterson in 2003. Subsequently, several certificateless two-party key agreement protocols were presented. Unfortunately, some of these protocols are not as secure as they were claimed to be. We will show that some existing certificateless key agreement protocols do not satisfy the requirements of key-compromise impersonation security and known session-specific temporary information security. Further more, we present two improved certificateless authenticated two-party key agreement protocols which possess all security attributes of a key agreement protocol.
Certificateless public key cryptography (CL-PKC) is a new paradigm in public key cryptography which avoids the inherent key escrow problem of identity-based public key cryptography (ID-PKC) and yet requires no certificates to guarantee the authenticity of users' public keys. It was first introduced by Al-Riyami and Paterson in 2003. Subsequently, several certificateless two-party key agreement protocols were presented. Unfortunately, some of these protocols are not as secure as they were claimed to be. We will show that some existing certificateless key agreement protocols do not satisfy the requirements of key-compromise impersonation security and known session-specific temporary information security. Further more, we present two improved certificateless authenticated two-party key agreement protocols which possess all security attributes of a key agreement protocol.
Authenticated key agreement protocol is used to provide data confidentiality and integrity to 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 PKI. In this paper, we present a secure and efficient two-party authenticated key agreement protocol based on the certificateless encryption scheme due to Libert and Quisquater. Security analysis shows that it achieves 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. Compared to other comparable schemes, it is more secure and efficient.
Authenticated key agreement protocol is a fundamental building block for ensuring private communications between two or more parties over an insecure network. Certificateless public key cryptography (CL-PKC) combines the advantage of the identity-based public key cryptography (ID-PKC) and the traditional PKI. In the recent work, Wang et al. proposed an efficient two-party certificateless authenticated key agreement protocol from pairings used to protect the Web client/server communication. However, we found the scheme cannot withstand key compromise impersonation attack, and also, is vulnerable to one form of the man-in-the-middle attack -- key replicating attack, thus it doesn't possess some desirable security attributes,such as key compromise impersonation resilience and key integrity. We analyze the key replicating attack against the protocol in the BR93 security model in detail, and demonstrate that the protocol is not secure if the adversary was allowed to send a reveal query to reveal non-partner players who had accepted the same session key.
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.
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.
Certificateless cryptography aims at combining the advantages of identity based and public key cryptography in order to avoid the key escrow problem inherent in the identity based cryptography and cumbersome certificate management in the traditional public key infrastructure. The provably secure certificateless key agreement protocol is proposed by Lippold et al. in 2009, but their protocol suffers from computation burden. Owing to the above-mentioned situations, a new certificateless two party key agreement protocol (CL-KA) is proposed and the security attributes are analyzed in the extended Canetti-Krawzcyk(eCK) security model. Our protocol only requires each entity to compute two pairings, up to now, it turns out to be the most efficient one of all the previously known security CL-KA schemes.
In an open and distributed environment, authenticated key agreement protocol, as an important cryptographic primitive, is used to authenticate entities and establish session key in order to provide secure communications. Certificateless public key cryptography (CL-PKC) combines the advantage of the identity-based public key cryptography (ID-PKC) and the traditional PKI. In this paper, we propose a new protocol based on CL-PKC. The new proposed protocol achieves most of the required security attributes. Security analysis shows that it achieves the attributes of forward secrecy, known-key secrecy, no-key control, key compromise impersonation and key replicating.