Keccak-256
Keccak-256 is a cryptographic hash function used widely in the Ethereum ecosystem and related tooling.
Keccak-256 outputs a 256-bit digest and is used for address derivation, logs/topics, and contract selectors in Ethereum-like environments. It's similar to standardized SHA-3 but differs in padding details.
"Function selectors are the first 4 bytes of the Keccak-256 hash of the signature string."
"Event topics in logs use Keccak-256 of the event signature for indexing."
Ethereum's keccak differs from NIST SHA-3 due to padding; implementations must use the correct variant for compatibility.
"Using SHA3-256 instead of Keccak-256 produces different digests and breaks address calculations."
"Ethash combines Keccak and memory-hard steps for PoW, while Keccak-256 alone is a general-purpose hash."
Related Terms
Hash
→A hash is a fixed-size output produced by a one-way function that maps any input to a seemingly random value, used for integrity, addressing, and proof-of-work.
Ethereum Virtual Machine (EVM)
→The Ethereum Virtual Machine (EVM) is the runtime environment for executing smart contracts on the Ethereum blockchain and EVM-compatible networks.
Ethereum (ETH)
→Ethereum (ETH) is a decentralized, open-source blockchain network featuring smart contract functionality.
Ethash
→Ethash is Ethereum's Proof-of-Work (PoW) hashing algorithm, designed to be ASIC-resistant and memory-intensive to promote decentralization.
All terms and definitions may update as the Cryptionary improves.
