From ecc
Prevents Ethereum hashing bugs in JavaScript/TypeScript by using true Keccak-256 instead of Node's NIST SHA3-256. For selectors, signatures, storage slots, and address derivation.
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Ethereum uses Keccak-256, not the NIST-standardized SHA3 variant exposed by Node's `crypto.createHash('sha3-256')`.
Conducts multi-source web research with firecrawl and exa MCPs: searches, scrapes pages, synthesizes cited reports. For deep dives, competitive analysis, tech evaluations, or due diligence.
Interactively installs Everything Claude Code skills and rules to user-level (~/.claude) or project-level (.claude) directories, verifies paths, and optimizes files. Activate on 'configure ecc' or setup requests.
Guides safe schema changes, data migrations, rollbacks, and zero-downtime deployments for PostgreSQL, MySQL, and ORMs like Prisma, Drizzle, Django.
Ethereum uses Keccak-256, not the NIST-standardized SHA3 variant exposed by Node's crypto.createHash('sha3-256').
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
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, toBytes } from 'viem';
const hash = keccak256(toBytes('hello'));
const hash = web3.utils.keccak256('hello');
const packed = web3.utils.soliditySha3(
{ type: 'address', value: '0x742d35Cc6634C0532925a3b8D4C9B569890FaC1c' },
{ type: 'uint256', value: '100' },
);
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 { keccak256 } from 'ethers';
function pubkeyToAddress(pubkeyBytes: Uint8Array): string {
const hash = keccak256(pubkeyBytes.slice(1));
return '0x' + hash.slice(-40);
}
grep -rn "createHash.*sha3" --include="*.ts" --include="*.js" --exclude-dir=node_modules .
grep -rn "keccak256" --include="*.ts" --include="*.js" . | grep -v node_modules
For Ethereum contexts, never use crypto.createHash('sha3-256'). Use Keccak-aware helpers from ethers, viem, web3, or another explicit Keccak implementation.