Paper 2025/2066

A Comprehensive Analysis of the AKMA+ Protocol

Abstract

With the rapid advancement of 5G networks and the increasing demand for secure application access, the Authentication and Key Management for Applications (AKMA) framework was developed by the 3rd Generation Partnership Project (3GPP) to provide unified authentication and key management for diverse 5G services. In response to the security and privacy concerns identified in the current AKMA protocol, as outlined in 3GPP TR 33.835, Yang et al. proposed an enhanced, standard-compatible 5G AKMA protocol known as AKMA+[14]. This paper presents a comprehensive analysis of AKMA+, discovering two critical vulnerabilities: (1) the compromise of the AKMA Anchor Function (AAnF), which enables adversaries to impersonate legitimate users; and (2) the persistent storage of multiple anchor keys, which heightens the risk of key exposure. These vulnerabilities arise from the reliance on the authentication framework inherent in existing AKMA+ models. This architectural dependency introduces fundamental security risks that cannot be adequately mitigated through incremental modifications to the current design. Furthermore, we observe that AKMA+ faces challenges in aligning with the standard account-based authentication model, which is incompatible with existing user practices within information systems. Additionally, we find that providing account-based authentication functionality without compromising privacy poses significant difficulties.