Industrial Internet-of-Things (IIoT) is the basis of Industry 4.0, which extends Internet connectivity beyond traditional computing devices like computers and smartphones to the physical world for improving efficiency and accuracy while reducing the production cost. However, there are tremendous security threats to IIoT, such as IIoT device hijacking and data leaks. Therefore, a lightweight authenticated key agreement (AKA) protocol is commonly applied to establish a session key for securing the communication between IIoT devices. To protect the previous session keys from being compromised, perfect forward secrecy (PFS) has been one of the most important security properties of AKA. In this work, we present an efficient PFS-enabled AKA protocol for IIoT systems, which is developed based on a new dynamic authentication credential (DAC) framework, without using any public-key cryptographic primitives. It is worth noting that our protocol is also faster than the state-of-the-art DAC-based AKA protocols with PFS. Moreover, we give the formal security result of the proposed protocol in the random oracle model.

Blockchain rewriting with fine-grained access control allows a user to create a transaction associated with a set of attributes, while a modifier who possesses sufficient rewriting privileges from a trusted authority satisfying the attribute set can anonymously rewrite the transaction. However, it lacks accountability and is not designed for open blockchains that require no centralized trust authority. In this work, we introduce accountable fine-grained blockchain rewriting in a permissionless setting. The property of accountability allows the modifier’s identity and their rewriting privileges to be held accountable for the modified transactions in case of malicious rewriting. Our contributions are three-fold. First, we present a generic framework for secure blockchain rewriting in the permissionless setting. Second, we present an instantiation of our framework and show its practicality through evaluation analysis. Last, we demonstrate that our proof-of-concept implementation can be effectively integrated into open blockchains.

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.

Attribute-Based Encryption (ABE) provides fine-grained access control to encrypted data and finds applications in various domains. The practicality of ABE schemes hinges on the balance between security and efficiency. The state-of-the-art adaptive secure ABE scheme, proven to be adaptively secure under standard assumptions (FAME, CCS'17), is less efficient compared to the fastest one (FABEO, CCS'22) which is only proven secure under the Generic Group Model (GGM). These traditional ABE schemes focus solely on message privacy. To address scenarios where attribute value information is also sensitive, Anonymous ABE (A²BE) ensures the privacy of both the message and attributes. However, most A²BE schemes suffer from intricate designs with low efficiency, and the security of the fastest key-policy A²BE (proposed in FEASE, USENIX'24) relies on the GGM. In this paper, we propose novel fast key-policy and ciphertext-policy ABE schemes that (1) support both AND and OR gates for access policies, (2) have no restriction on the size and type of policies or attributes, (3) achieve adaptive security under the standard DLIN assumption, and (4) only need 4 pairings for decryption. As our ABE constructions automatically provide ciphertext anonymity, we easily transform our ABE schemes to A²BE schemes while maintaining the same features and high-level efficiency. The implementation results show that all our schemes achieve the best efficiency comparing to other schemes with adaptive security proven under standard assumptions. Specifically, our ABE schemes perform better than FAME and are close to FABEO. Our key-policy A²BE scheme performs close to the one in FEASE and our ciphertext-policy A²BE outperforms the state-of-the-art (Cui et al., ProvSec'16).

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.

Bluetooth low energy (LE) devices have been widely used in the Internet of Things (IoT) and wireless personal area networks (WPAN). However, attackers may compromise user privacy by tracking the addresses of the LE device. The resolvable private address (RPA) mechanism provides address privacy protection for the LE device. Similar to Zhang and Lin’s work in CCS 2022, we investigate the privacy of the RPA mechanism in this paper. Our contributions are threefold. First, we discover that the RPA mechanism has a privacy weakness. The attacker can track the targeted device by exploiting the runs of the RPA mechanism when he intercepts the targeted device’s obsolete RPA value. Second, we propose an improved RPA mechanism to overcome the privacy weakness in the RPA mechanism. The improved RPA mechanism leads to a small amount of extra overheads without requiring modification to the basic cryptographic tools used in the standard specification. Third, we formalize a privacy model to capture the address privacy of the RPA mechanisms. Our improved RPA mechanism provides enhanced privacy guarantees to Bluetooth LE devices in wireless personal applications.