Zether - The first privacy mechanism designed for Ethereum

I thought this might be share-worthy.

Benedikt Bunz (co-author of Bulletproofs), Dan Bohen et al. proposed Zether, the first privacy mechanism built specifically for Ethereum, i.e. account-based smart contract platforms. All notable blockchain privacy mechanisms developed so far (the authors refer to 10 of them), were designed for Bitcoin/UTXO-based chains.

Zether provides both confidentiality (by hiding payment amounts) and anonymity (by hiding the identities of senders and recipients).

The mechanism is practical today (no changes to Ethereum protocol required). The authors implemented it as an Ethereum smart contract and a single transaction costs 7M+ gas :slight_smile: , but if two already discussed EIPs were to be implemented, it would go down to 1.7M and also the contract itself could be further optimized.


Where can we find the smart contract code for this protocol

great paper :slight_smile: we may use this in our network

I reviewed this some time ago at https://medium.com/coinmonks/notes-on-zether-towards-privacy-in-a-smart-contract-world-6c4333f975d

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Sorry for the late reply @kunxian-xia, here’s a part of the implementation: https://github.com/bbuenz/BulletProofLib/tree/master/src/main/java/edu/stanford/cs/crypto/efficientct/zetherprover.

What are the benefits of Zether compared to AZTEC?

Few differences I can identify:

  • Zether is using the account model (no extra storage required if one is doing many split transactions)
  • Zether doesn’t require a trusted setup, but AZTEC requires it only once for many contracts (they separate the engine into a different smart contract)
  • AZTEC is cheaper and easier to reason about.

Any other feedback someone can share?

Hi @MihailoBjelic,
I wonder if you could share what kind of progress have been made and if there are any difficulties you guys faced so far?