Public blockchains, though renowned for their transparency and immutability, suffer from significant privacy concerns. Network-level analysis and long-term observation of publicly available transactions can often be used to infer user identities. To mitigate this, several blockchain applications rely on relayers, which serve as intermediary nodes between users and smart contracts deployed on the blockchain. However, dependence on a single relayer not only creates a single point of failure but also introduces exploitable vulnerabilities that weaken the system's privacy guarantees. This paper proposes a decentralized relayer architecture that enhances privacy and reliability through game-theoretic incentive design. We model the interaction among relayers as a non-cooperative game and design an incentive mechanism in which probabilistic uploading emerges as a unique mixed Nash equilibrium. Using evolutionary game analysis, we demonstrate the equilibrium's stability against perturbations and coordinated deviations. Through numerical evaluations, we analyze how equilibrium strategies and system behavior evolve with key parameters such as the number of relayers, upload costs, rewards, and penalties. In particular, we show that even with high transaction costs, the system maintains reliability with an outage probability below 0.05 . Furthermore, our results highlight a fundamental trade-off between privacy, reliability, robustness, and cost in decentralized relayer systems.

翻译：公共区块链虽以透明性和不可篡改性著称，却存在显著的隐私隐患。通过对公开交易的网络级分析和长期观测，往往可推断用户身份。为缓解此问题，若干区块链应用依赖中继器作为用户与链上部署的智能合约之间的中介节点。然而，依赖单一中继器不仅会形成单点故障，还会引入可被利用的漏洞，从而削弱系统的隐私保障。本文提出一种去中心化中继器架构，通过博弈论激励设计增强隐私性与可靠性。我们将中继器间的交互建模为非合作博弈，并设计一种激励机制，其中概率性上传成为唯一的混合纳什均衡。通过演化博弈分析，我们证明了该均衡对扰动与协同偏离的稳定性。借助数值评估，我们分析了均衡策略与系统行为如何随中继器数量、上传成本、奖励与惩罚等关键参数演变。特别地，我们证明即使在高交易成本下，系统仍能保持可靠性，其中断概率低于0.05。此外，我们的结果揭示了去中心化中继器系统中隐私性、可靠性、鲁棒性与成本之间的根本权衡关系。