The 5G-AKA protocol, defined by 3GPP for authentication and key agreement in 5G networks, remains vulnerable to linkability, synchronization failure, and Sequence Number (SQN) exposure attacks. These issues threaten user privacy and service availability. Existing improvements often retain these flaws or cause high overhead due to continued use of the legacy SQN mechanism from 3G. In this paper, we propose 5G-RNAKA, a secure and efficient AKA protocol for 5G systems. Unlike 5G-AKA, 5G-RNAKA eliminates SQN counters and instead utilizes random numbers generated by the Universal Subscriber Identity Module (USIM) in 5G User Equipment (UE) for session identification. This random number is embedded in the reply message from the service network (SN) to prevent replay attacks against the UE. Additionally, by removing the SQN mechanism, 5G-RNAKA enhances user privacy by preventing attackers from linking challenge-response sessions. It also enables the UE to authenticate the SN, effectively mitigating the risk of SN impersonation. We formally verify that 5G-RNAKA achieves its security goals of privacy, authentication, and secrecy using the state-of-the-art formal verification tool, Tamarin Prover. Our implementation and evaluation further demonstrate that 5G-RNAKA improves communication efficiency and reduces storage overhead. While primarily designed for 5G, 5G-RNAKA's features align with emerging trends in 6G authentication, suggesting its potential for adaptation to future 6G architectures.

The Data Distribution Service (DDS) constructs a highly available data transmission middleware based on the publish-subscribe model, widely used in the Internet of Things environment. To improve the security of DDS, the Object Management Group formulated the DDS Security, which provides security mechanisms for DDS in the form of security plugins. However, the security of the DDS Security protocol has not been fully analyzed. We analyze DDS Security through formal methods. We model the security goals and protocol flow of the DDS Security using ProVerif and evaluate whether its security goals can be met in different scenarios. Our analysis confirms previously manually identified vulnerabilities in an automated way and reveals new attacks. We discovered the permission file impersonation attack, the denial of service attack, the degradation attack, and the privacy leakage attack guided by the formal analysis result. For these threats, we propose corresponding mitigation measures and recommendations.

The FIDO protocol suite aims at allowing users to log in to remote services with a local and trusted authenticator. With FIDO, relying services do not need to store user-chosen secrets or their hashes, which eliminates a major attack surface for e-business. Given its increasing popularity, it is imperative to formally analyze whether the security promises of FIDO hold. In this paper, we present a comprehensive and formal verification of the FIDO UAF protocol by formalizing its security assumptions and goals and modeling the protocol under different scenarios in ProVerif. Our analysis identifies the minimal security assumptions required for each of the security goals of FIDO UAF to hold. We confirm previously manually discovered vulnerabilities in an automated way and disclose several new attacks. Guided by the formal verification results, we also discovered two practical attacks on two popular Android FIDO apps, which we responsibly disclosed to the vendors. In addition, we offer several concrete recommendations to fix the identified problems and weaknesses in the protocol.