Keccak-256 Hash Calculator
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All hashing runs in your browser. Data is never sent to any server.
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1. How to Use
- Enter text or upload a file to calculate Keccak-256 hash.
- Click 'Generate Keccak-256 Hash' for Ethereum-compatible output.
- Use for smart contract testing or Web3 development.
- Verify Keccak256 hashes for Ethereum transaction or message signing.
- Note: Keccak-256 ≠ SHA3-256; Ethereum uses Keccak (original padding).
2. How It Works
Keccak-256 uses the Keccak sponge with 256-bit output. The key difference from SHA3-256 is the padding: Keccak uses pad01*1 (append 0x01, pad with 0x00, final 0x80); SHA3 uses 0x06.
Same Keccak-f permutation: 1600-bit state, 24 rounds of θ, ρ, π, χ, ι. Rate r=1088, capacity c=512 for 256-bit security.
Logic: Absorb(input) = state XOR pad(input) in r-bit blocks; Squeeze() = output from state in r-bit blocks. Keccak256 = first 256 bits of Squeeze().
Ethereum's keccak256 is this Keccak-256. Solidity and EVM use it for addresses, transaction hashes, and contract storage.
3. About Keccak-256
Keccak-256 is the original Keccak algorithm before NIST's SHA-3 padding change. Ethereum and Web3 use Keccak-256 throughout.
This Keccak-256 hash calculator produces hashes identical to Ethereum's keccak256. Use it for smart contract development, address derivation, and Web3 debugging.
All computation runs in your browser.
4. Advantages
- Ethereum compatibility: Matches Solidity keccak256 and EVM opcodes exactly.
- Web3 development: Essential for dApp and smart contract work.
- Deterministic: Same input always yields same hash.
- Privacy: No server calls.
5. Real-World Use Cases
- Smart contracts: Test Keccak-256 hashes for Solidity code.
- Ethereum addresses: Part of the address derivation (Keccak256 of pubkey).
- Transaction hashes: Ethereum tx hashes use Keccak-256.
- Web3 libraries: Verify hashes from ethers.js, web3.js, or other libs.