An event data recorder (EDR) is a device installed in a vehicle to record information. Similar to a black box in an airplane, an EDR is used in the study of automobile accidents. Many schemes have been proposed that use vehicle network technology to help record EDR data, including schemes involving storing data on roadside units or nearby vehicles and schemes leveraging blockchain technology. However, these schemes do not take into account the vehicle company’s server; with the increased use of autonomous vehicles, the data related to these vehicles are always uploaded to the vehicle company’s server. In this scenario, we classify the situation into different cases, according to whether or not it is an emergency and whether the vehicle and the server are connected. For these cases, we propose a scheme whereby a vehicle uploads the EDR data to a cloud server and sends the evidence of storage to the nearby vehicle through a vehicular ad hoc network. Our scheme offers a fast response due to the use of symmetric cryptography algorithms while also considering security requirements.

Sensitive data collected by a wireless sensor network (WSN) should be protected by a secret key shared between two adjacent (or neighboring) sensors. Sensors are mobile devices with limited memory and computational power, and sensors are deployed in a field randomly in which relative positions among sensors cannot be pre‐determined. Key distribution in WSN is a challenging research problem. Random key distribution is one of the most popular key distribution techniques in WSN; but it is a probabilistic key distribution scheme since two neighboring sensors may or may not share any pairwise key. There are many published papers to improve the probability of connectivity of two neighboring sensors. In this paper, a novel design of lightweight key establishment is proposed based on top of random key distribution. The first scheme can increase the probability of connectivity of two neighboring sensors, and the second scheme can also enable sensors to authenticate the established pairwise key. Both schemes need only XOR operation so they are lightweight and especially suitable for WSNs.

In vehicular networks, the increasing value of transportation data and scale of connectivity also brings many security and privacy concerns. Peer authentication and message integrity are two vital security requirements to ensure safe transportation system. Because of the constrained resources of the units performing the cryptographic components, the proposed security-enhancing schemes should be lightweight and scalable. In this paper, we present a multisignature scheme derived from the SM2 signature which enables a group of parties to collaboratively sign a message and generate a compact joint signature at the end. Our scheme requires no preprocessing or interactions among the parties before signing, and its performance matches or surpasses known ones in terms of signing time, verification time, and signature size. Therefore, our scheme is also suitable for vehicular networks, with the goal to enhance security with small computation and storage cost.

Large Language Model (LLM) interaction records are increasingly being used as digital evidence for forensics and compliance. However, traditional linear tamper-evident logs cannot capture the complex nonlinear conversation evolution, such as prompt-editing, response regeneration, session deletion, multi-device concurrency, and selective sharing. This study proposes the Verifiable Conversation Transcript (VCT), which models these operations as authenticated account-level state transitions across a three-layer cryptographic structure: Q&A pairs form branch hash chains and branch tails aggregate into session-level Merkle roots (${\mathrm{MTR}}_{\mathrm{con}}$). These session-level roots are further aggregated into the account-level Merkle root (${\mathrm{MTR}}_{\mathrm{acc}}$), which is jointly authenticated by both user and server signatures. The VCT also introduces a serialized deletion protocol, a deterministic merge protocol that preserves concurrent non-deletion updates, a gossip-based fork detection mechanism that produces non-repudiable forensic evidence, and a verifiable sharing protocol that constructs an independent dual-signed share hash chain across disclosed nodes. Based on standard cryptographic assumptions, the VCT guarantees integrity, consistency, share verifiability, and non-repudiation of account-level conversation records. A Python prototype achieves sub-millisecond mean latency under minimal state with short synthetic payloads. With 21 KB per-node payloads, the estimated metadata-to-content ratio is approximately 0.9% across the tested account scales. These results support the computational feasibility of the prototype under the tested conditions and provide practical guidance for the engineering design and optimization of verifiable LLM conversation systems.