Zyfi - Permissionless Multi Signer Paymaster

A singular permissionless multi-signer paymaster allowing multiple dapps to seamlessly sponsor gas for their users through signature verification.

This project is scaffolded with zksync-cli.

Overview

• This paymaster is a signature based paymaster, it sponsor gas fees for any user transaction if valid signature is provided.

• Any Dapps can integrate this paymaster by simply depositing gas funds and adding a signer address.

• Signature is validated against the added signer address, and gas funds for sponsorship are deducted from Dapp's account(Manager) as per usage upon correct validation.

• Signature signing shall be done off-chain as per requirement by each Dapp.

• "Permissionless" - Multiple Dapps can use this paymaster without any restrictions. Deposit gas funds, sponsor gas, withdraw at any time.

• "Multi-signer" - It allows Dapps to add multiple signers whose signature will be verified before gas sponsorship for the users. Ensuring gas funds are only accessed if Dapp approves off-chain.

• There are 2 primary actors involved:

  • Manager: Fully managed by the Dapp, responsible for depositing/withdrawing gas funds, and adding or removing signer addresses.
  • Signers: Managed by the dApp or a trusted third party like Zyfi’s API. A signer’s signature is required to access gas funds by the Dapp's user.

Please check technical-specs.md and our documentation for detailed information & integration.

Benefits

This signature based implementation allows the following features:

• Protocols can implement any business logic to decide their which users should be provided gas sponsorship.
• No need for Dapps to to be dependant on 3rd party for paymaster services.
• No need for Dapps to deploy paymaster with custom business logic.
• Easy integration to your Dapp with optional Zyfi API support available.

Contract address

Network	Address
ZKsync Mainnet	0x68b4F1146a863d0E7cF1e134857411C8a941C86d
ZKsync Sepolia Testnet	0xc1B0E2edC4cCaB51A764D7Dd8121CBf58C4D9E40

Project structure

• /contracts: smart contracts.
• /deploy: deployment and contract interaction scripts.
• /test: test files

Commands

• npx zksync-cli dev start to start a local node. It can be checked with docker logs --follow zkcli-in-memory-node-zksync-1
• yarn install will install the dependencies.
• yarn compile will compile the contracts.
• yarn test will run tests. Check test requirements below.
• npx zksync-cli dev start can be used to set up an explorer or dapp for local tests

Environment variables

In order to prevent users to leak private keys, this project uses environment variables. It's used to load the wallet private key, required to run the deploy and interact script.

To use it, rename .env.example to .env and enter your private key.

WALLET_PRIVATE_KEY=0x123cde574ccff....
SIGNER_PRIVATE_KEY=0x123cde574ccff....

Local Testing

Install dependencies

• Node version 18 or above.

yarn install

- Hardhat

yarn test

- Fork environment

1. Start inMemoryNode with Era_test_node in terminal. See installation here

era_test_node fork mainnet

2. Run below command in another terminal

yarn test-local

Links

• Technical Specs
• Zyfi portal
• Documentation