International Association
for Cryptologic Research

As the use of the internet and digital devices has grown rapidly, keeping digital communications secure has become very important. Authenticated Key Agreement (AKA) protocols play a vital role in securing digital communications. These protocols enable the communicating parties to mutually authenticate and securely establish a shared secret key. The emergence of quantum computers makes many existing AKA protocols vulnerable to their immense computational power. Consequently, designing new protocols that are resistant to quantum attacks has become essential. Extensive research in this area had led to the design of several post-quantum AKA schemes. In this paper, we analyze two post-quantum AKA schemes proposed by Dharminder et al. [2022] and Pursharthi and Mishra. [2024] and demonstrate that these schemes are not secure against active adversaries. An adversary can impersonate an authorized user to the server. We then propose reliable solutions to prevent these attacks.