In IoT-enabled electricity markets, trading is often conducted in a forward-style manner, where parties agree on prices and quantities in advance and settle upon future delivery. However, deploying such forward-style exchanges across chains is incompatible with execution-restricted blockchains and typically incurs significant cross-chain gas overhead. Moreover, existing low-overhead cross-chain mechanisms, particularly HTLC-based schemes, inherently rely on pairwise locking and thus cannot efficiently support one-to-many settlement. We propose an inter-chain forward-style exchange framework based on a dual-track validation architecture. The framework integrates a double-spend fraud-proof mechanism to ensure correctness and a proof-of-acceptance (PoAc) mechanism to reduce cross-chain overhead for successful settlements. We further introduce a novel k-directional hash lock enabling one-to-many settlement, allowing a single buy order to be split across multiple sellers. Our analysis shows that the framework resists griefing attacks, prevents adversarial losses, and preserves cross-chain atomicity. Experiments demonstrate support for execution-restricted blockchains such as Bitcoin, scalability to 862,000 sellers per order, and a 78.25% reduction in settlement cost compared to light-client approaches.

Transaction propagation delay limits the block interval and is one of the main bottlenecks in improving Bitcoin throughput. However, transaction relay in Bitcoin is entirely voluntary, which results in low bandwidth and high transaction propagation delay. Improving relay motivation by introducing incentives can effectively reduce delay, but it still faces challenges such as Sybil attacks during reward allocation, leakage of network layer privacy, and high on-chain/off-chain overhead. Therefore, this paper proposes Txtail, a practical transaction relay incentive scheme for Bitcoin, based on continuously attaching relay evidence representing the relays’ identity and contribution during transaction propagation. We employ a free pricing mechanism based on the game between relays to allocate rewards fairly. We design an order-insensitive relay evidence structure based on aggregate signatures and public key mapping, which reduces off-chain data overhead while alleviating the leakage of relay paths by obfuscating the relay order. We construct a verifiable lottery mechanism based on Merkle tree commitments to reduce the data that needs to be uploaded to the chain. Both theoretical and experimental results show that Txtail reduces the per-hop off-chain overhead and the overall on-chain overhead by 96.6% and 79.8%, respectively, compared with state-of-the-art baselines, while remaining practical for deployment.

Cross-chain auction is a promising paradigm for enabling on-chain price discovery across blockchain systems. While existing bridge solutions can functionally support cross-chain auctions, their deployment across heterogeneous blockchains remains challenging. In addition, conventional hash time-lock contracts (HTLCs) inherently predetermine the receiver, making them incompatible with the flexible recipient assignment required in auction settings. In this paper, we propose recipient-agnostic hash locks (RAHL), a new primitive that extends the HTLC framework to support dynamic recipient selection. By leveraging adaptor signatures and the UTXO model, we construct mutually exclusive pre-payments that allow multiple potential receivers to participate, while ensuring that only one is ultimately finalized. Furthermore, we embed adaptor signatures with polynomial commitments such that the secret revealed during settlement encodes recipient information, thereby enabling recipient-agnostic functionality. We formally model RAHL under a rational cross-chain communication (CCC) setting, and prove that it satisfies effectiveness and atomicity, while providing resilience against front-running and temporary censorship attacks. Experimental results demonstrate that RAHL primitive supports auctions between Bitcoin and Ethereum, reducing cross-chain settlement overhead by 33% compared to representative light-client approaches.

Tor's original design does not have an incentive mechanism but relies on volunteers to maintain their relay nodes for free, eventually leading to the current situation of centralization and lack of relay nodes. Current incentive schemes designed for Tor generally rely on centralized roles, thus presenting a risk of destroying Tor's anonymity. This paper proposes R2E, a decentralized scheme that treats Tor relay services as cryptocurrency mining and rewards the relays with generated tokens while addressing the challenge of how to design decentralized protocols that quantify workload while ensuring fairness and anonymity. We construct the Proof-of-Relay protocol in R2E that enforces random circuit selection, limits the number of nonce attempts, and exploits one-time keys and zero-knowledge proofs to protect participants' identities. We implemented a prototype of R2E based on Ethereum and conducted the trial operation and several confirmation experiments involving$2^{20}$clients,$2^{10}$to$2^{16}$nodes, and 256 circuits for each client to demonstrate its applicability. Analysis and experimental results show that R2E can effectively ensure the anonymity of participants' identities and fairness of incentive allocation while showing good performance in overhead and scalability, making it easy to be quickly applied in practical deployments.