Keccak256 – How to Use Ethers.js to Hash Data

ethers.jshashkeccaksignature

I tried to use ethers' keccak256 function like this:

import { keccak256 } from "@ethersproject/keccak256";

const signature = keccak256("balanceOf(address)");

But the script failed with this error:

Error: invalid arrayify value (argument="value", value="balanceOf(address)", code=INVALID_ARGUMENT, version=bytes/5.5.0)

How can I make it work?

Best Answer

Let's look at the function definition for keccak256:

export function keccak256(data: BytesLike): string {
    return '0x' + sha3.keccak_256(arrayify(data));
}

The input is not a string - it's a BytesLike type.

With that in mind, here's how to rewrite the script to make it work:

import { keccak256 } from "@ethersproject/keccak256";
import { toUtf8Bytes } from "@ethersproject/strings";

const signature = keccak256(toUtf8Bytes("balanceOf(address)"));

The trick is to import another package from the ethers stack (@ethersproject/strings) that exports a function called toUtf8Bytes, which converts your string to BytesLike.

Related Solutions

[Ethereum] SOLIDITY: How to get a bytes32 keccak256 hash of an address and 2 uint256 variables

As reported in this thread: https://github.com/ethereum/solidity/issues/3955

The new abi.encode*() methods offer a replacement to perform packing, which then can be passed to all these hashing functions.

Bottom line: As @mirg commented, just use abi.encodePacked() inside keccak256(). That is:

keccak256(abi.encodePacked(msg.sender, _unixTimestamp, _timeExpired))

Ethers.js Solidity – How to Read Public Variable from Contract

actually in solidity docs it's pointing that for each public member variable there will be a getter is defined automatically. In short you'll be able to get basic type public member like this: let x = await contract.totalAllocPoint(); you've been missing parenthesis here.

While you can get array like: let y = await contract.poolInfo(2); if the array length is more than 3 in this case of course.

For mapping types

mapping (address => mapping(uint256 => Order)) public orderByAssetId;
await contract.orderByAssetId(address, id);

To explain it more, if you look into ABI generated from compiling your solidity contract you should be able to see like this:

Defined contract in solidity

contract MasterChef {
...
  uint256 public totalAllocPoint = 0;
...
}

equals to ABI

  {
    "inputs": [],
    "name": "totalAllocPoint",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },

Keep on coding !

With Human-Readable ABI of ethers.js

const contract = new ethers.Contract(contractAddress, [
   'function totalAllocPoint() public view returns (uint256)'
], provider)

await contract.totalAllocPoint()

Best Answer

Related Solutions

[Ethereum] SOLIDITY: How to get a bytes32 keccak256 hash of an address and 2 uint256 variables

Ethers.js Solidity – How to Read Public Variable from Contract

Related Topic