International Association
for Cryptologic Research

Certificate-based cryptography is a new public-key cryptographic paradigm that has very appealing features, namely it simplifies the certificate management problem in traditional public key cryptography while eliminating the key escrow problem in identity-based cryptography. So far, three authenticated key agreement (AKA) protocols in the setting of certificate-based cryptography have been proposed in the literature. Unfortunately, none of them are secure under the public key replacement (PKR) attack. In this paper, we first present a security model for certificate-based AKA protocols that covers the PKR attacks. We then explore the existing three certificate-based AKA protocols and show the concrete attacks against them respectively. To overcome the weaknesses in these protocols, we propose a new certificate-based AKA protocol and prove its security strictly in the random oracle model. Performance comparison shows that the proposed protocol outperforms all the previous certificate-based AKA protocols.