Paper 2020/560 Original: eprint.iacr.org/2020/560 ↗

Zerojoin: Combining Zerocoin and CoinJoin

Alexander Chepurnoy
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
Preprint.
History
2021-08-29: last updated
2020-05-15: published
Short URL
https://ia.cr/2020/560
License
https://creativecommons.org/licenses/by/4.0/

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},
      url = {https://eprint.iacr.org/2020/560}
}
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