Paper 2020/560

Zerojoin: Combining Zerocoin and CoinJoin

Alexander Chepurnoy and Amitabh Saxena

Abstract

We present Zerojoin, a privacy-enhancing protocol for UTXO blockchains. Like Zerocoin, our protocol uses zero-knowledge proofs and a pool of participants. However, unlike Zerocoin, our pool size is not monotonically increasing. Thus, our protocol overcomes the major drawback of Zerocoin. Our approach can also be considered a non-interactive variant of CoinJoin, where the interaction is replaced by a public transaction on the blockchain. The security of Zerojoin relies on the Decisional-Diffie-Hellman (DDH) assumption. We also present ErgoMix, a practical implementation of Zerojoin on top of Ergo, a smart contract platform based on Sigma protocols. While Zerojoin contains the key ideas, it leaves open the practical issue of handling fees. The key contribution of ErgoMix is a novel approach to handle fees in Zerojoin.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Published elsewhere. MINOR revision.Data Privacy Management, Cryptocurrencies and Blockchain Technology. DPM 2020, CBT 2020.
Keywords
cryptocurrencyprivacyDDHzero knowledge
Contact author(s)
kushti @ protonmail ch
History
2021-08-29: last of 4 revisions
2020-05-15: received
See all versions
Short URL
https://ia.cr/2020/560
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2020/560,
      author = {Alexander Chepurnoy and Amitabh Saxena},
      title = {Zerojoin: Combining Zerocoin and CoinJoin},
      howpublished = {Cryptology ePrint Archive, Paper 2020/560},
      year = {2020},
      note = {\url{https://eprint.iacr.org/2020/560}},
      url = {https://eprint.iacr.org/2020/560}
}
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