nodejs-keccak256
Prevent Ethereum hashing bugs in JavaScript and TypeScript. Node's sha3-256 is NIST SHA3, not Ethereum Keccak-256, and silently breaks selectors, signatures, storage slots, and address derivation.
npx skills add mturac/everything-openai-codex --skill nodejs-keccak256 --agent codex
Same command for any agent — swap --agent for claude-code, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# 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. ```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 ``` ## Examples ### 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], ); ``` ### viem ```typescript import { keccak256, toByte
- When to Use
- How It Works
- Examples
- ethers v6
- viem
- web3.js
- Common patterns
- Address from public key
- Audit your codebase
- Rule
grep -rn "createHash.*sha3" --include="*.ts" --include="*.js" --exclude-dir=node_modules . grep -rn "keccak256" --include="*.ts" --include="*.js" . | grep -v node_modules
What does the nodejs-keccak256 skill do?
Prevent Ethereum hashing bugs in JavaScript and TypeScript. Node's sha3-256 is NIST SHA3, not Ethereum Keccak-256, and silently breaks selectors, signatures, storage slots, and address derivation.
How do I install it?
Run `npx skills add mturac/everything-openai-codex --skill nodejs-keccak256 --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From mturac/everything-openai-codex, a repository with 84 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.