hardhat-zksync-verify

This plugin is used to verify contracts on the ZKsync Era network.

Changelog

Prerequisite

To use hardhat-zksync-verify in your project, ensure the following:

• Node.js version 18 or higher is installed.
• Hardhat version 2.16.0 or higher is installed as a dependency.

Setup

The @matterlabs/hardhat-zksync-verify plugin is used in conjunction with @nomicfoundation/hardhat-verify and it supports backward compatibility. To use it, install both plugins and then import @matterlabs/hardhat-zksync-verify in the hardhat.config.ts file.

yarn add -D @matterlabs/hardhat-zksync-verify @nomicfoundation/hardhat-verify

Configuration

Import the plugin in the hardhat.config.ts file:

import "@matterlabs/hardhat-zksync-verify";

Add the verifyURL property to the ZKsync Era network in the hardhat.config.ts file as shown below:

networks: {
    sepolia: {
      url: "https://sepolia.infura.io/v3/<API_KEY>" // The Ethereum Web3 RPC URL (optional).
    },
    zkTestnet: {
      url: "https://sepolia.era.zksync.dev", // The testnet RPC URL of ZKsync Era network.
      ethNetwork: "sepolia", // The Ethereum Web3 RPC URL, or the identifier of the network (e.g. `mainnet` or `sepolia`)
      zksync: true,
      // Verification endpoint for Sepolia
      verifyURL: 'https://explorer.sepolia.era.zksync.dev/contract_verification'
    }
},
// defaultNetwork: "zkTestnet", // optional (if not set, use '--network zkTestnet')

Additional network properties:

• zkTestnet is an arbitrary ZKsync Era network name. You can select this as the default network using the defaultNetwork property.
• url is a field with the URL of the ZKsync Era node in case of the ZKsync Era network (with zksync flag set to true), or the URL of the Ethereum node. This field is required for all ZKsync Era and Ethereum networks used by this plugin.
• ethNetwork is a field with the URL of the Ethereum node. You can also provide network name (e.g. sepolia) as the value of this field. In this case, the plugin will either use the URL of the appropriate Ethereum network configuration (from the networks section), or the default ethers provider for the network if the configuration is not provided. This field is required for all ZKsync networks used by this plugin.
• zksync is a flag that indicates a ZKsync Era network configuration. This field is set to true for all ZKsync Era networks. If you want to run a hardhat-verify verification, this field needs to be set to false. If set to true, the verification process will try to run the verification process on the ZKsync Era network.
• verifyURL is a field that points to the verification endpoint for the specific ZKsync network. This parameter is optional, and its default value is the testnet verification url.
  • Testnet: https://explorer.sepolia.era.zksync.dev/contract_verification
  • Mainnet: https://zksync2-mainnet-explorer.zksync.io/contract_verification

If you want to verify a smart contract on the Ethereum in the same project, it is important to add etherscan field and API key in the hardhat.config.ts file:

networks: {
    ...
},
etherscan: {
  apiKey: //<Your API key for Etherscan>,
},

Commands

yarn hardhat verify --network <network> <contract address>

This command verifies the contract on the given network with the given contract's address.

When executed in this manner, the verification task attempts to compare the compiled bytecode of all the contracts in your local environment with the deployed bytecode of the contract you are seeking to verify. If there is no match, it reports an error.

yarn hardhat verify --network <network> <contract address> --contract <fully qualified name>

With the --contract parameter you can also specify which contract from your local setup you want to verify by specifying its Fully qualified name. Fully qualified name structure looks like this: "contracts/AContract.sol:TheContract"

Constructor arguments

If your contract was deployed with the specific constructor arguments, you need to specify them when running the verify task. For example:

yarn hardhat verify --network testnet 0x7cf08341524AAF292255F3ecD435f8EE1a910AbF "Hi there!"

If your constructor takes a complex argument list, you can write a separate javascript module to export it. For example, create an arguments.js file with the following structure:

module.exports = [
  "a string argument",
  "0xabcdef",
  "42",
  {
    property1: "one",
    property2: 2,
  },
];

Include it in the verify function call by adding a new parameter: --constructor-args arguments.js:

yarn hardhat verify --network testnet 0x7cf08341524AAF292288F3ecD435f8EE1a910AbF --constructor-args arguments.js

The hardhat-zksync-verify plugin also supports the verification with encoded constructor parameters.

In order to use the encoded parameters, you need to specify a separate javascript module and export them as a non-array parameter. It is important for encoded arguments to start with 0x in order to be recognized by the plugin. For example:

module.exports = "0x0x00087a676164696a61310000087a676164696a61310000000000000000000000008537b364a83f5c9a7ead381d3baf9cbb83769bf5";

Verification status check

The verification process consists of two steps:

• A verification request is sent to confirm if the given parameters for your contract are correct.
• Then, we check the verification status of that request. Both steps run when you run the verify task, but you will be able to see your specific verification request ID. You can then use this ID to check the status of your verification request without running the whole process from the beginning.

The following command checks the status of the verification request for the specific verification ID:

yarn hardhat verify-status --verification-id <your verification id>

Verify smart contract programmatically

If you need to run the verification task directly from your code, you can use the hardhat verify:verify task with the previously mentioned parameters with the difference in using --address parameter when specifying contract's address.

const verificationId = await hre.run("verify:verify", {
  address: contractAddress,
  contract: contractFullyQualifedName,
  constructorArguments: [...]
});

This task returns a verification id if the request was successfully sent.

You can use this id to check the status of your verification request as described in the section above.

If you are using encoded constructor args, constructorArguments parameter should be a non-array value starting with 0x.

const verificationId = await hre.run("verify:verify", {
  address: contractAddress,
  contract: contractFullyQualifedName,
  constructorArguments: "0x12345...",
});