Stanford University researchers and Visa Research have developed a privacy mechanism for Ethereum (ETH) smart contracts. A write up describing the mechanism was published on Stanford University’s Applied Cryptography Group website.
According to the write up, the researchers created “a fully-decentralized, confidential payment mechanism” called “Zether” that is consistent with both Ethereum and other smart contract platforms. They reportedly developed a new smart contract that can be executed either individually or by other smart contracts that maintains the account balances encrypted and enables the deposit, transfer and withdrawal of funds through cryptographic proofs.
They claim in the report that transactions on Zether are confidential. One transaction costs approximately 0.014 ETH or around $1.51 at press time. Enhanced confidentiality is said to be enabled by the option to lock funds in an account to a smart contract. The type of anonymity guaranteed by Zether is more similar to Monero (XMR). The report says:
“We describe an extension to Zether that can also hide the sender and receiver involved in a transaction among a group of users chosen by the sender. Though the overhead associated with anonymity scales linearly with the size of the group, no trusted set-up is needed and no changes to the underlying smart contract platform are required.”
The report continued thus: “The Zether contract will never transfer funds without first checking an appropriate burn or transfer proof, even if the request comes from another smart contract whose rules do not permit illegal transfers. This design decision ensures that the security of Zether only depends on itself and not on any outside smart contract. Even a maliciously written or insecure smart contract cannot cause Zether to misbehave,”