ZKsync Smart accounts demo

This project was scaffolded with zksync-cli.

This demo project contains different examples to deploy a basic smart contract account and use it to interact with a Greeter.sol contract.

Important info about smart accounts on ZKsync

Using acronym "SCA" for Smart Contract Accounts.

ZKsync implements native account abstraction. Given that SCAs (and paymasters) are first class citizens on ZKsync, they must follow certain rules to adhere to the protocol specification. It's strongly recommended to read the following pages from the ZKsync documentation:

• https://docs.zksync.io/build/developer-reference/account-abstraction
• https://docs.zksync.io/build/developer-reference/account-abstraction/design
• https://docs.zksync.io/build/developer-reference/account-abstraction/extending-4337
• https://docs.zksync.io/build/developer-reference/account-abstraction/building-smart-accounts

Considerations for building smart accounts

• SCAs on ZKsync must implement the IAccount.sol interface methods. This interface is provided in the zksync-contracts NPM package and in this repository.

• SCAs must increase the account nonce in the validateTransaction and return a specific ACCOUNT_VALIDATION_SUCCESS_MAGIC value if validation is successful. This value is provided in the IAccount.sol contract.

• Given that SCAs interact with the NonceHolder system contract to increase the nonce, SCAs must be compiled with enableEraVMExtensions: true in the compiler settings. Example:

  zksolc: {
    version: "1.5.1",
    settings: {
      enableEraVMExtensions: true
    },
  },

• SCAs must be deployed via the createAccount or create2Account method of the ContractDeployer.sol system contract. The hardhat-zksync plugin provides the hre.deployer object that allows passing the deployment type as a parameter on the deploy method. See deploy-dummy-acc.ts script for reference.

const artifact = await hre.deployer.loadArtifact(contractArtifactName);
  const contract = await hre.deployer.deploy(artifact, constructorArguments, 
  // deployment type
  "createAccount");

• SCAs deployed using the default create or create2 will not be identified as accounts by the protocol and sending transactions from these accounts will result in the error Validation revert: Sender is not an account.

• Factory contracts that deploy other contracts must know the bytecodeHash of the contract that they'll deploy (normally passed as a factory constructor param) and its correspondent bytecode (passed as factory_deps on deployment). See the deploy-dummy-fac.ts and deploy-dummy-proxy-fac.ts scripts as reference. Learn more about contract deployments on ZKsync here.

• If the SCA is a proxy with the account logic in a different implementation contract, then the proxy must be deployed with createAccount or create2Account. The implementation can be deployed with create or create2.

Setup

• Install dependencies with npm i
• See the hardhat.config.ts for the required compiler configuration.
• Select your desired default network (tested in inMemoryNode and zkSyncSepoliaTestnet).
• Compile all contracts with npx hardhat compile.
• Deploy the Greeter.sol contract with npx hardhat deploy-zksync --script deploy.ts.

Different deployments and tests

Default deployment

The DummyAccount.sol contract is a very basic smart contract account. The verification logic has been removed (for simplicity of this examples) and accepts any signature as valid.

This example deploys the account directly using hre.deployer.deploy and interacts with a Greeter contract.

1. Deploy the contract with npx hardhat deploy-zksync --script deploy-dummy-acc.ts.
2. Copy the contract address in the ACCOUNT_ADDRESS variable in the fund-acc.ts script. Run the script to fund the account with npx hardhat deploy-zksync --script fund-acc.ts.
3. Add the smart contract account address and the Greeter contract address in the interact-dummy.ts file. Run the script with ``npx hardhat deploy-zksync --script interact-dummy.ts`

Factory account deployment

Using the same DummyAccount.sol contract from the default deployment example.

In this example, the account is deployed from a factory contract (DummyFactory.sol).

1. Deploy the factory contract and an account with npx hardhat deploy-zksync --script deploy-dummy-fac.ts.
2. Copy the account address in the ACCOUNT_ADDRESS variable in the fund-acc.ts script. Run the script to fund the account with npx hardhat deploy-zksync --script fund-acc.ts.
3. Add the smart contract account address and the Greeter contract address in the interact-from-fac-acc.ts file. Run the script with ``npx hardhat deploy-zksync --script interact-from-fac-acc.ts`

Factory proxy account deployment

In this example, we'll have a factory that deploys smart accounts that are proxies. For this, we'll use the DummyInitAccount.sol (which inherits from Openzeppelin initializable), and the DummyProxyFactory.sol factory contract.

1. Deploy the implementation that will be used by our proxy smart contract accounts (DummyInitAccount.sol)with npx hardhat deploy-zksync --script deploy-dummy-init-acc.ts.
2. Copy the address and add it to deploy-dummy-proxy-fac.ts file.
3. Deploy the factory contract and a proxy account with npx hardhat deploy-zksync --script deploy-dummy-proxy-fac.ts.
4. Copy the account address in the ACCOUNT_ADDRESS variable in the fund-acc.ts script. Run the script to fund the account with npx hardhat deploy-zksync --script fund-acc.ts.
5. Add the smart contract account address and the Greeter contract address in the interact-from-proxyed-acc.ts file. Run the script with ``npx hardhat deploy-zksync --script interact-from-proxyed-acc.ts`

Testnet addresses and tx hashes:

• Greeter: 0x543A5fBE705d040EFD63D9095054558FB4498F88
• DummyInitAccount (proxy implementation logic): 0xbE0e545504Eb4fA9Fa0de8D01CC227A4A3B8558D
• DummyProxyFactory: 0x1609b7C8318991228c71a0b3cC11bBF95c3c7A3F
• Deployed proxy account: 0x4944DECe0b3ae884edDd9B8C6b316b889DADEDD7
• Transaction to deploy proxy account from factory: 0x08c2d157f94877845b802ad7f23f595df2d0f9cb4558b47275f8e886e791e8ef
• Transaction sent from proxy account: 0x632aae3f362c32dc070d12a8538ee4374e0f5b99bbdd1686994ab707cb894605

Troubleshooting

• Funding the proxy smart contract accounts must be done from an account different from the proxy owner.

Project Layout

• /contracts: Contains solidity smart contracts.
• /deploy: Scripts for contract deployment and interaction.
• /test: Test files.
• hardhat.config.ts: Configuration settings.

Useful Links

• Docs
• Official Site
• GitHub
• Twitter
• Discord

License

This project is under the MIT license.