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Recently, Roy et al. proposed a physically unclonable function (PUF)-based authentication and key exchange protocol for Internet of Things (IoT) devices. The PUF protocol is efficient, because it integrates both the Node-to-Node (N2N) authentication and the Node-to-Server (N2S) authentication into a standalone protocol. In this paper, we therefore examine the security of the PUF protocol under the assumption of an insider attack. Our cryptanalysis findings are the following. (1) A legitimate but malicious IoT node can monitor the secure communication among the server and any other IoT nodes in both N2N authentication and N2S authentication. (2) A legitimate but malicious IoT node is able to impersonate a target IoT node to cheat the server and any other IoT nodes in N2N authentication and the server in N2S authentication, respectively. (3) A legitimate but malicious IoT node can masquerade as the server to cheat any other target IoT nodes in both N2N authentication and N2S authentication. To the best of our knowledge, our work gives the first non-trivial concrete security analysis for the PUF protocol. In addition, we employ the automatic verification tool of security protocols, i.e., Scyther, to confirm the weaknesses found in the PUF protocol. We finally consider how to prevent weaknesses in the PUF protocol.

Recently, Zerrouki et al. proposed a Physically Unclonable Function (PUF) mutual authentication and session key establishment protocol for IoT (Internet of Things) devices. Zerrouki et al.’s PUF protocol is interesting because it does not require the storage of any sensitive information on the local memory of the IoT device, which avoids many potential attacks, especially side-channel attacks. Therefore, we carefully investigate the security of Zerrouki et al.’s PUF protocol under the leakage assumption of the session key. Our findings are in the following. First, Zerrouki et al.’s PUF protocol fails to provide known-key security. That is, the adversary can impersonate not only the server to cheat the IoT device but also the IoT device to cheat the server when the adversary corrupts a session key between the server and the IoT device. Second, Zerrouki et al.’s PUF protocol suffers from the key-compromise impersonation attack. It means that the adversary can impersonate the IoT device to cheat the server if the adversary discloses the server’s secret key. Third, Zerrouki et al.’s PUF protocol does not support backward secrecy for the session key. That is, the adversary is always able to derive the session key from the previous session key. We also suggest the root cause of these security flaws in Zerrouki et al.’s PUF protocol. As a case study, our cryptanalysis results would promote a security model for more robust and efficient PUF authentication and session key establishment protocol. Moreover, our idea of the key compromise can be used to evaluate other novel PUF protocol designs.

With the rapid development of cloud computing and mobile networks, more and more application scenarios require a secret group key for secure communication. Group Key Exchange (GKE) protocol provides a secret group key for three or more members. Burmester and Desmedt presented an influential GKE protocol, which has a broadcast version and a cyclic version. In this paper, we investigate the security weaknesses of the Burmester-Desmedt protocol. We report that both the broadcast version and the cyclic version of the Burmester-Desmedt protocol suffer member tampering attacks if the two members that belong to both group A and group B are corrupted. That is, two corrupted members can add some unknowing members of group A to group B and trick the legal members of group B to believe that these unknowing members share the secret group key with them after a protocol run. Furthermore, to defeat the member tampering attack, we propose digital signature-based improvements on the broadcast version and the cyclic version of the Burmester-Desmedt protocol. We hope our research results will encourage the development of more robust and effective GKE protocols that stand rigorous security analysis.

Vinoth et al. proposed an authenticated key agreement scheme for industrial IoT (Internet of Things) applications. Vinoth et al.’s scheme aimed to protect the remote sensing data of industrial IoT devices under hostile environments. The scheme is interesting because the authorized user is allowed simultaneously to access the multiple IoT sensing devices. Therefore, we carefully analyzed the security and privacy implications of Vinoth et al.’s scheme. Our findings are summarized as follows. One, Vinoth et al.’s scheme failed to defeat user impersonation attacks. Second, Vinoth et al.’s scheme did not prevent IoT sensing device impersonation attacks. Third, Vinoth et al.’s scheme suffered from replay attacks. Fourth, Vinoth et al.’s scheme was vulnerable to desynchronization attacks. Fifth, Vinoth et al.’s scheme could not maintain user privacy. As a case study, our analysis results enlighten researchers and engineers on the design of robust and efficient authenticated key agreement schemes for IoT applications.

Bluetooth low energy devices are very popular in wireless personal area networks. According to the Bluetooth standard specifications, the low energy secure simple pairing (LESSP) protocol is the process by which the pairing devices negotiate the authenticated secret key. To violate the user privacy, the adversary can perhaps link the runs of the LESSP protocol to the targeted device, which usually relates to the specially appointed user. Hence, we investigate deep into the privacy of the LESSP protocol. Our main contributions are threefold: (1) We demonstrate that the LESSP protocol suffers from privacy vulnerability. That is, an adversary without any secret key is able to identify the targeted device by the LESSP protocol. (2) An improvement is therefore proposed to repair the privacy vulnerability in the LESSP protocol. (3) We develop a formal privacy model to evaluate the privacy vulnerabilities in the LESSP protocol and its improved versions. We further prove that our improvement on the LESSP protocol is private under the privacy model. In addition, the performance evaluation shows that our improvement is as efficient as the LESSP protocol. Our research results are beneficial to the privacy enhancement of Bluetooth systems in wireless personal area networks.

Bluetooth is an important technical standard for short-range and low-power wireless communication. The home automation and entertainment (HAE) systems often make use of Bluetooth technology to link different Bluetooth devices and form Bluetooth networks. The security concerns of the HAE systems are raised due to massive deployment of the Bluetooth devices. The Bluetooth standard mainly depends on the secure simple pairing (SSP) solution to protect the Bluetooth devices. Hence, we investigate the SSP solution according to the Bluetooth standard v5.0. The contributions are threefold. (1) A formal security model is proposed to evaluate SSP’s association models and authenticated link key. (2) We formally analyze two SSP protocols and present the security requirements for basic cryptographic modules in these SSP protocols. (3) We discuss the typical SSP applications in the HAE systems. Our results are useful to not only evaluating and designing the SSP protocols but also enhancing the security of the HAE systems in which the Bluetooth access is available.