In Internet of Things (IoT) scenarios, the integrity audit of massive amounts of data uploaded from Edge Nodes (ENs) to the cloud poses significant challenge to researchers. Existing Provable Data Possession (PDP) schemes suffer from low communication and computational efficiency, as well as the issue of Third-Party Auditors (TPAs) not being completely trustworthy, especially in dynamic data update scenarios. This paper designs an efficient authentication structure, named the Weighted Link-list Chameleon Hash Authentication Tree (WLCHAT), to reduce cloud storage overhead and improve dynamic update efficiency. Based on this, the paper further proposes the WLCHAT-PDP scheme, which is built upon the WLCHAT structure. Building on the PDP model, the proposed scheme introduces the ENs to proxy user operations for tag generation and to participate in the audit process. By combining this with a user authorization signature mechanism, the proposed scheme not only alleviates terminal computational load but also guarantees that all operations are authorized. To enhance the credibility of the audit process, the proposed scheme incorporates blockchain-anchored log records to effectively prevent collusive behavior between cloud service providers and TPAs. Theoretical analyses and comparative evaluation demonstrate that the scheme achieves a balance between security and computational overhead, rendering it suitable for dynamic and trusted IoT cloud storage environments.

Password-based authenticated key exchange (PAKE) protocol has been widely used in practice, since it is convenient for users. However, the easy-to-remember property of the password also brings security problem. In this paper, we show there is an off-line dictionary attack in an efficient PAKE protocol when the smart card is lost. In order to resist the attack, we give a countermeasure to improve it. The countermeasure makes a simple change to the original protocol which does not affect the efficiency of the protocol.