Paper 2022/951

MixCT: Mixing Confidential Transactions from Homomorphic Commitment

Jiajun Du, Shanghai Jiao Tong University
Zhonghui Ge, Shanghai Jiao Tong University
Yu Long, Shanghai Jiao Tong University
Zhen Liu, Shanghai Jiao Tong University
Shifeng Sun, Shanghai Jiao Tong University
Xian Xu, East China University of Science and Technology
Dawu Gu, Shanghai Jiao Tong University

Mixing protocols serve as a promising solution to the unlinkability in blockchains. They work by hiding one transaction among a set of transactions and enjoy the advantage of high compatibility with the underlying system. However, due to the inherently public nature of the blockchains built on the account-based model, the unlinkability is highly restricted to non-confidential transactions. In the account-based model, blockchains supporting confidential payments need to trade their compatibility for unlinkability. In this paper, we propose MixCT, a generic protocol that provides the mixing service for confidential payment systems built from homomorphic commitment in the account-based model. We formally define the security goals including safety and availability, and prove that our generic construction satisfies them. Furthermore, we provide an efficient instantiation of MixCT by the Pedersen commitment and the one-out-of-many proof. The evaluation results show that MixCT introduces a small cost for its users while being highly compatible with the underlying confidential blockchain.

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blockchainconfidential transactionmixing service
Contact author(s)
cqdujiajun @ sjtu edu cn
zhonghui ge @ sjtu edu cn
longyu @ sjtu edu cn
liuzhen @ sjtu edu cn
shifeng sun @ sjtu edu cn
xuxian @ ecust edu cn
dwgu @ sjtu edu cn
2022-07-23: approved
2022-07-23: received
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      author = {Jiajun Du and Zhonghui Ge and Yu Long and Zhen Liu and Shifeng Sun and Xian Xu and Dawu Gu},
      title = {{MixCT}: Mixing Confidential Transactions from Homomorphic Commitment},
      howpublished = {Cryptology ePrint Archive, Paper 2022/951},
      year = {2022},
      note = {\url{}},
      url = {}
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