Counter-Based Session Key Establishment Protocol for Efficient and Forward Secrecy in Bluetooth BR/EDR
Woori Bae, Taek-Young Youn, Nam-Su Jho · IEEE Access · 2026
Bluetooth technology has become an essential element of wireless communications, enabling short-range data transfer between a variety of devices; therefore, ensuring security and privacy is critical. In recent years, attacks against Bluetooth have increased. In response, various research efforts have proposed countermeasures. The paper ‘‘BLUFFS: Bluetooth Forward and Future Secrecy Attacks and Defenses" in 2023 discovered vulnerabilities in standard Bluetooth protocols, indicating that they could be exposed to BLUFFS, an attack that can compromise both past and future communication sessions. The work proposed an enhanced protocol to address these vulnerabilities by introducing additional procedures into the standard protocol to improve secrecy and integrity, but these modifications increase the complexity of the protocol and reduce its efficiency. Despite continued research, there has been no follow-up work addressing these limitations. Therefore, this paper aims to reduce the number of communication packets required during session establishment while maintaining the high security level proposed in the BLUFFS work. To this end, we design two new protocols based oncounterand efficient use of a message authentication code(MAC).We analyze their security against BLUFFS and show that they provide forward secrecy. Our protocols complete session key establishment in 8 packets — the same as the standard Legacy Secure Connections(LSC) — whereas Enhanced-Legacy Secure Connections(E-LSC) requires 10. Also, each protocol reduces execution time by 15.6% and 10.4% under end-to-end execution-time benchmarking. Our protocols use the key derivation function(KDF) specified in the standard. Thus, our approach improves efficiency while preserving compatibility with the standard, as demonstrated by comparison with E-LSC. In practice, keeping the LSC packet count and following the standard KDF path are expected to enable easy firmware-level integration with existing BR/EDR stacks. However, legacy devices that lack counter storage and synchronization support may face compatibility issues.