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.
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- Dépôt
- Jamkris/everything-gemini-code
- Dernière activité de la source
- 10 avril 2026 à 04:19
- Langue détectée de SKILL.md
- anglais
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- 93
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- 23
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SKILL.md
Instructions source · Aperçu en lecture seule- name
- nodejs-keccak256
- description
- 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.
- origin
- ECC direct-port adaptation
- version
- 1.0.0
# 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, toBytes } from 'viem';
const hash = keccak256(toBytes('hello'));
```
### web3.js
```javascript
const hash = web3.utils.keccak256('hello');
const packed = web3.utils.soliditySha3(
{ type: 'address', value: '0x742d35Cc6634C0532925a3b8D4C9B569890FaC1c' },
{ type: 'uint256', value: '100' },
);
```
### Common patterns
```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]),
);
}
```
### Address from public key
```typescript
import { keccak256 } from 'ethers';
function pubkeyToAddress(pubkeyBytes: Uint8Array): string {
const hash = keccak256(pubkeyBytes.slice(1));
return '0x' + hash.slice(-40);
}
```
### Audit your codebase
```bash
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.
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