Generate Ethereum-compatible Keccak-256 hashes for blockchain and smart contracts.
About
Keccak-256 is the Ethereum blockchain's hash function, differing from SHA3-256 only in padding, producing a 256-bit hash using the original Keccak submission (capacity 512, rate 1088).
Specifications
Output Size256 bits
StandardKeccak submission to NIST SHA-3 competition
Standard Year2008
Use Cases
—Ethereum address and transaction hashing
—Smart contract development
—Blockchain and DApp applications
Frequently Asked Questions
Keccak-256 is generally 2-4x slower than SHA-256 in software implementations on x86-64 processors. SHA-256 benefits from hardware acceleration (Intel SHA-NI) on modern CPUs, while Keccak-256 relies on software optimization. However, Keccak-256 is natively resistant to length extension attacks without requiring HMAC, which can simplify certain implementations.
For Ethereum compatibility, Keccak-256 is required. For new independent blockchains, consider whether Ethereum compatibility is important. SHA3-256 offers the same security with NIST standardization. BLAKE3 provides significantly better performance if speed is critical. Keccak-256 is a solid choice but consider your specific ecosystem requirements.
Keccak-256 and SHA3-256 are nearly identical but differ in padding: Keccak-256 uses suffix 0x01, while SHA3-256 uses 0x06. This difference produces completely different outputs. Keccak-256 is the original submission (2008), while SHA3-256 is the NIST standardized version (2015).
Ethereum adopted Keccak-256 before NIST finalized the SHA-3 standard with different padding. By the time SHA3-256 was standardized, Ethereum's codebase and deployed smart contracts already used Keccak-256. Changing would have broken all existing addresses and contracts, so Ethereum continues using the original Keccak variant.
Yes, both provide identical security levels with 128-bit collision resistance and 256-bit preimage resistance. The only difference is the padding byte, which does not affect security. Both use the same Keccak-f[1600] permutation with 24 rounds and are considered cryptographically secure.