PCT: Preserving the Privacy of Cross-Chain Transfer
发表信息
作者
- Panpan Han
- Zheng Yan
- Laurence T Yang
- Elisa Bertino
笔记
Blockchain-enabled digital currency systems have typically operated in isolation, lacking necessary mechanisms for seamless interconnection. Consequently, transferring assets across distinct currency systems remains a complex challenge, with existing schemes often falling short in ensuring security, privacy, and practicality. This paper proposes P2C2T — a privacy-preserving cross-chain transfer scheme. It is the first scheme to address atomicity, unlinkability, indistinguishability, non-collateralization, and required functionalities across diverse currency systems. P2C2T is based on \textit{threshold anonymous atomic locks} (TA2L), also proposed by us, serving as the cornerstone for guaranteeing atomic cross-chain transfer while obscuring the payment relationships between users. By combining TA2L with \textit{verifiable timed discrete logarithm} schemes, P2C2T renders cross-chain transactions indistinguishable from regular intra-chain ones. Notably, P2C2T eliminates the collateralization of senders and imposes minimal requirements on underlying blockchains, specifically on the ability to verify signatures. We substantiate the security of TA2L based on a proposed cryptographic notion called \textit{threshold blind conditional signatures} and demonstrate the security of P2C2T through necessary proofs. Additionally, we compare the performance of P2C2T with an existing scheme that has properties closest to P2C2T. The comparison reveals that P2C2T reduces overhead by at least 85.488% in terms of running time, communication cost, and storage cost when completing a cross-chain transfer. We further conduct cross-chain transfers and intra-chain payments using the Bitcoin testnet and Litecoin testnet to illustrate the privacy and practicality of P2C2T.
区块链驱动的数字货币系统通常孤立运行，缺乏无缝互联的必要机制。因此，跨不同货币系统的资产转移仍是一个复杂难题，现有方案往往难以兼顾安全性、隐私性和实用性。本文提出P2C2T——一种保护隐私的跨链转移方案。作为首个同时解决原子性、不可关联性、不可区分性、无抵押要求及跨货币系统功能需求的方案，P2C2T基于我们提出的”阈值匿名原子锁”(TAL)技术，该技术既能保证跨链转移的原子性，又能模糊用户间的支付关联。通过将TAL与”可验证时序离散对数”方案结合，P2C2T使得跨链交易与常规链内交易无法区分。值得注意的是，P2C2T免除了发送方的抵押要求，并对底层区块链仅提出最低限度要求——只需具备签名验证能力。我们基于新提出的密码学概念”阈值盲条件签名”论证了TAL的安全性，并通过必要证明展示了P2C2T的安全保障。与特性最接近的现有方案相比，P2C2T在完成跨链转移时，其运行时间、通信开销和存储成本至少降低。我们进一步利用比特币测试网和莱特币测试网进行跨链转移与链内支付实验，验证了P2C2T的隐私保护能力和实用价值。