The payment channel network (PCN) is an effective off-chain scaling solution widely recognized for reducing operational costs on permissionless blockchains. However, it still faces challenges such as lack of flexibility, channel exhaustion, and poor sustainability. Currently, a separate deposit is required for each payment channel, which locks a significant amount of coins for a longer period. This restricts the ability to move locked coins across their channels off-chain. Additionally, unbalanced (unidirectional) transfers can lead to channel exhaustion, rendering the channel unsustainable. To address these issues, we propose a novel off-chain flexible PCN protocol called Flexichain . Unlike existing approaches, Flexichain allows users to deposit coins per user rather than per channel. This provides flexibility to move coins freely between channels without relying on the blockchain or disrupting the off-chain cycle. Flexichain is proven to be secure under the Universal Composability framework and resistant against channel exhaustion attacks. To assess the performance of Flexichain, we conduct experiments on both on-chain and off-chain operations using snapshots of the Lightning Network. We evaluate the on-chain gas costs, success ratio and success amount of off-chain payments under uniform and skewed payment demands, as well as the computational and communication overheads of the off-chain contracts.

Social Internet of Vehicle (SIoV) has emerged as one of the most promising applications for vehicle communication, which provides safe and comfortable driving experience. It reduces traffic jams and accidents, thereby saving public resources. However, the wrongly communicated messages would cause serious issues, including life threats. So it is essential to ensure the reliability of the message before acting on considering that. Existing works use cryptographic primitives like threshold authentication and ring signatures, which incurs huge computation and communication overheads, and the ring signature size grew linearly with the threshold value. Our objective is to keep the signature size constant regardless of the threshold value. This work proposes MuSigRDT, a multisignature contract based data transmission protocol using Schnorr digital signature. MuSigRDT provides incentives, to encourage the vehicles to share correct information in real-time and participate honestly in SIoV. MuSigRDT is shown to be secure under Universal Composability (UC) framework. The MuSigRDT contract is deployed on Ethereum's Rinkeby testnet.

Social Internet of Vehicles (SIoV) is an emerging technology in the smart city environment, enabling smart vehicles to form social groups and exchange data among themselves. SIoV facilitates many applications aiming to improve driving safety and traffic monitoring by sharing data among vehicles. It ensures a safe and comfortable drive. However, privacy, data confidentiality, and data integrity are the major challenges during multi-hop data transfer that must be addressed for the wide adoption of SIoV. The existing solutions do not provide anonymity and consume more network resources. To address these issues, we propose SIoVChain, a time-lock contract-based privacy-preserving data sharing scheme with incentives for SIoV. It does not only enable data sharing between vehicles anonymously but incentivizes them also. In addition, the proposed framework imposes a penalty anonymously if a malicious vehicle disseminates false information. SIoVChain is shown to be secure against stealing processing fee attack while preserving sender-receiver privacy and path privacy. Universal Composability (UC) framework is used to verify user privacy. The feasibility and efficiency of the scheme are also demonstrated.