SHA-3 and Keccak Are Not the Same Hash: A Tour of One Padding Byte

SHA3-256('') and Keccak-256('') produce completely different 32-byte outputs even though they run the same permutation. The difference is one byte appended to the input during padding — 0x06 versus 0x01 — and it is the reason Ethereum's keccak256 will never agree with Node's crypto.createHash('sha3-256').