Nodejs Keccak256

by affaan-mef648e01899bNo license275K starsListed Oct 8, 2026Updated Oct 8, 2026Repository updated 3 days ago

JavaScriptとTypeScriptにおけるEthereumハッシュバグを防ぐ。NodeのSHA3-256はNIST SHA3であり、Ethereum Keccak-256ではなく、セレクター、署名、ストレージスロット、アドレス導出を静かに破壊する。

Instructions onlySoftware Development

AI-generated overview

Guides JavaScript and TypeScript developers to use Keccak-256 instead of Node's NIST SHA3-256 when hashing Ethereum data.

What it does: Explains that Ethereum uses Keccak-256 while Node's crypto.createHash('sha3-256') exposes the NIST-standardized SHA3 variant, and that the two produce different outputs without warning. It provides code examples for computing hashes, function selectors, event topics, EIP-712 type hashes, storage slots, and addresses using ethers v6, viem, and web3.js, plus grep commands for auditing a codebase. It states the rule to never use crypto.createHash('sha3-256') in Ethereum contexts.
When to use it: Use it when computing Ethereum function selectors or event topics, building EIP-712, signature, Merkle, or storage-slot helpers in JS/TS, or reviewing code that hashes Ethereum data with Node's crypto module.
Requirements: Requires a JavaScript/TypeScript project and one of the Keccak-capable libraries shown (ethers, viem, or web3.js). No scripts are shipped; it is instructions and code examples only.

Node.js Keccak-256

EthereumはKeccak-256を使用し、Nodeのcrypto.createHash('sha3-256')が公開するNIST標準化SHA3バリアントではない。

使用するタイミング

Ethereum関数セレクターやイベントトピックの計算
JS/TSでEIP-712、署名、Merkle、またはストレージスロットヘルパーの構築
Nodeのcryptoを直接使用してEthereumデータをハッシュするコードのレビュー

仕組み

2つのアルゴリズムは同じ入力に対して異なる出力を生成し、Nodeは警告しない。

javascript

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

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

例

ethers v6

typescript

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],);

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

web3.js

javascript

const hash = web3.utils.keccak256('hello');const packed = web3.utils.soliditySha3(  { type: 'address', value: '0x742d35Cc6634C0532925a3b8D4C9B569890FaC1c' },  { type: 'uint256', value: '100' },);

const hash = web3.utils.keccak256('hello');const packed = web3.utils.soliditySha3(  { type: 'address', value: '0x742d35Cc6634C0532925a3b8D4C9B569890FaC1c' },  { type: 'uint256', value: '100' },);

一般的なパターン

typescript

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]),  );}

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]),  );}

公開鍵からアドレス

typescript

import { keccak256 } from 'ethers';
function pubkeyToAddress(pubkeyBytes: Uint8Array): string {  const hash = keccak256(pubkeyBytes.slice(1));  return '0x' + hash.slice(-40);}

import { keccak256 } from 'ethers';
function pubkeyToAddress(pubkeyBytes: Uint8Array): string {  const hash = keccak256(pubkeyBytes.slice(1));  return '0x' + hash.slice(-40);}

コードベースの監査

bash

grep -rn "createHash.*sha3" --include="*.ts" --include="*.js" --exclude-dir=node_modules .grep -rn "keccak256" --include="*.ts" --include="*.js" . | grep -v node_modules

grep -rn "createHash.*sha3" --include="*.ts" --include="*.js" --exclude-dir=node_modules .grep -rn "keccak256" --include="*.ts" --include="*.js" . | grep -v node_modules

ルール

Ethereumコンテキストでは、crypto.createHash('sha3-256')を絶対に使用しない。ethers、viem、web3、または別の明示的なKeccak実装のKeccak対応ヘルパーを使用すること。

Source and attribution

Source:affaan-m/eccindocs/ja-JP/skills/nodejs-keccak256at commitef648e0

License: No license

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Nodejs Keccak256

Node.js Keccak-256

使用するタイミング

仕組み

例

ethers v6

viem

web3.js

一般的なパターン

公開鍵からアドレス

コードベースの監査

ルール

Source and attribution

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