Industrial Internet of Things (IIoT) facilitate private data collecting via (a broad range of) sensors, and the analysis of such data can inform decision making at different levels. Federated learning (FL) can be used to analyze the collected data, in privacy-preserving manner by transmitting model updates instead of private data in IIoT networks. The FL framework is, however, vulnerable because model updates are easily tampered with by malicious agents. Motivated by this observation, we propose a novel chameleon hash scheme with a changeable trapdoor (CHCT) for secure FL in IIoT settings. Our scheme imposes various constraints on the use of trapdoor. We give a rigorous security analysis on our CHCT scheme. We also instantiate the CHCT scheme as a redactable medical blockchain (RMB). The experimental evaluations demonstrate the practical utility of CHCT in terms of accuracy and efficiency.

As an essential element of the next generation Internet, Internet of Things (IoT) has been undergoing an extensive development in recent years. In addition to the enhancement of people's daily lives, IoT devices also generate/gather a massive amount of data that could be utilized by machine learning and big data analytics for different applications. Due to the machine-to-machine communication nature of IoT, data security and privacy are crucial issues that must be addressed to prevent different cyber attacks (e.g., impersonation and data pollution/poisoning attacks). Nevertheless, due to the constrained computation power and the diversity of IoT devices, it is a challenging problem to develop lightweight and versatile IoT security solutions. In this article, we propose an efficient, secure, and privacy-preserving message authentication scheme for IoT. Our scheme supports IoT devices with different cryptographic configurations and allows offline/online computation, making it more versatile and efficient than the previous solutions.

Radio Frequency IDentification (RFID) is a technology that has been widely employed in many applications requiring automatic object identification. Security and privacy are critical issues that must be addressed when the technology is deployed in security sensitive applications. The prior RFID protocols based on symmetric and asymmetric (or public) key cryptography have limitations in either security or practicality. In particular, public key based RFID protocols can achieve stronger security but are also more expensive in terms of the computation cost. In this paper, we propose a new public key based RFID protocol that incurs much less computation cost compared with the prior protocols. The novelty behind our protocol is to securely reuse public key operations across different sessions so that in most of the sessions only symmetric key operations are required. We show that our protocol can achieve mutual authentication, strong anonymity, forward privacy and non-deniability with low computation and communication cost.

Anonymous proxy signatures are very useful in the construction of anonymous credential systems such as anonymous voting and anonymous authentication protocols. As a basic requirement, we should ensure an honest proxy signer is anonymous. However, in order to prevent the proxy signer from abusing the signing right, we should also allow dishonest signers to be traced. In this paper, we present three novel anonymous proxy signature schemes with different levels of (namely, public, internal and original signer) traceability. We define the formal definitions and security models for these three different settings, and prove the security of our proposed schemes under some standard assumptions.

In a recent paper (IEEE Trans. Wireless Commun., vol. 14, no. 1, 2015), Heet al.proposed an accountable and privacy-enhanced access control (APAC) protocol, which aimed to provide privacy for honest users against network owners and accountability against misbehaving users without the involvement of any trusted third party. However, the level of trust on the network owner has not been clearly defined in Heet al.’s paper, and we demonstrate in this letter that in the case where the network owners cannot be trusted to correctly generate the system parameters, then the APAC protocol cannot ensure user privacy.

Signer anonymity is an important security requirement for many digital signature schemes due to the need of user privacy in many applications. In this paper, we study signer anonymity for proxy signature which allows a signer to delegate his/her signing right to another user (or proxy). Since the proxy signer is the actual singer in a proxy signature scheme, we are interested in protecting the proxy signer's identity in this paper. However, one potential problem in an anonymous proxy signature scheme is that the proxy signer may abuse the delegated signing right due to the anonymity property of a proxy signature. In this paper, we propose a novel anonymous proxy signature scheme with restricted traceability, which allows the original singer to trace dishonest proxy signers. However, if the proxy signer is honest, then his/her identity is well protected against any user (including the original signer). Our scheme will be useful in many applications such as anonymous authentication protocols and anonymous voting schemes.