what is ethash
Ethash is the proof-of-work function in Ethereum-based blockchain currencies. It uses Keccak, a hash function eventually standardized to SHA-3. These two are different, and should not be confused. From version 1.0 Ethash has been designed to be ASIC-resistant via memory-hardness (harder to implement in special ASIC chips) and easily verifiable. It also uses a slightly modified version of earlier Dagger and Hashimoto hashes to remove computational overhead.