nodejs-keccak256

Node.js Keccak-256 Ethereum uses Keccak-256, not the NIST-standardized SHA3 variant exposed by Node's crypto.createHash('sha3-256') . When to Use Computing Ethereum function selectors or event topics Building EIP-712, signature, Merkle, or storage-slot helpers in JS/TS Reviewing any code that hashes Ethereum data with Node crypto directly How It Works The two algorithms produce different outputs for the same input, and Node will not warn you. import crypto from 'crypto' ; import { keccak256 , toUtf8Bytes } from 'ethers' ; const data = 'hello' ; const nistSha3 = crypto . createHash ( 'sha3-256' ) . update ( data ) . digest ( 'hex' ) ; const keccak = keccak256 ( toUtf8Bytes ( data ) ) . slice ( 2 ) ; console . log ( nistSha3 === keccak ) ; // false Examples ethers v6 import { keccak256 , toUtf8Bytes , solidityPackedKeccak256 , id } from 'ethers' ; const hash = keccak256 ( new Uint8Array ( [ 0x01 , 0x02 ] ) ) ; const hash2 = keccak256 ( toUtf8Bytes ( 'hello' ) ) ; const topic = id ( 'Transfer(address,address,uint256)' ) ; const packed = solidityPackedKeccak256 ( [ 'address' , 'uint256' ] , [ '0x742d35Cc6634C0532925a3b8D4C9B569890FaC1c' , 100n ] , ) ; viem import { keccak256 , toBytes } from 'viem' ; const hash = keccak256 ( toBytes ( 'hello' ) ) ; web3.js const hash = web3 . utils . keccak256 ( 'hello' ) ; const packed = web3 . utils . soliditySha3 ( { type : 'address' , value : '0x742d35Cc6634C0532925a3b8D4C9B569890FaC1c' } , { type : 'uint256' , value : '100' } , ) ; Common patterns import { id , keccak256 , AbiCoder } from 'ethers' ; const selector = id ( 'transfer(address,uint256)' ) . slice ( 0 , 10 ) ; const typeHash = keccak256 ( toUtf8Bytes ( 'Transfer(address from,address to,uint256 value)' ) ) ; function getMappingSlot ( key : string , mappingSlot : number ) : string { return keccak256 ( AbiCoder . defaultAbiCoder ( ) . encode ( [ 'address' , 'uint256' ] , [ key , mappingSlot ] ) , ) ; } Address from public key import { keccak256 } from 'ethers' ; function pubkeyToAddress ( pubkeyBytes : Uint8Array ) : string { const hash = keccak256 ( pubkeyBytes . slice ( 1 ) ) ; return '0x' + hash . slice ( - 40 ) ; } Audit your codebase grep -rn "createHash.sha3" --include = ".ts" --include = ".js" --exclude-dir = node_modules . grep -rn "keccak256" --include = ".ts" --include = "*.js" . | grep -v node_modules Rule For Ethereum contexts, never use crypto.createHash('sha3-256') . Use Keccak-aware helpers from ethers , viem , web3 , or another explicit Keccak implementation.