Definition
Double SHA-256 means applying the SHA-256 hash function twice in sequence. The output of the first hash becomes the input of the second. This is sometimes written as hash256(x) = SHA-256(SHA-256(x)).
Satoshi Nakamoto chose double hashing as a defense against length extension attacks, which are a theoretical vulnerability of single-pass SHA-256. In practice, this means ASIC mining chips must compute two SHA-256 rounds per hash attempt.
In Simple Terms
Applying SHA-256 twice in sequence, the specific hashing method Bitcoin uses for block mining.
Double SHA-256 is a term used in Bitcoin mining related to mining basics.
Also known as: hash256, dSHA-256.
Double SHA-256 means applying the SHA-256 hash function twice in sequence. The output of the first hash becomes the input of the second. This is sometimes written as hash256(x) = SHA-256(SHA-256(x)).
Satoshi Nakamoto chose double hashing as a defense against length extension attacks, which are a theoretical vulnerability of single-pass SHA-256. In practice, this means ASIC mining chips must compute two SHA-256 rounds per hash attempt.
Understanding double sha-256 is important for Bitcoin miners because it directly impacts mining operations, hardware selection, or profitability calculations. Whether you are a home miner running a Bitaxe or operating a larger ASIC setup, this concept helps inform better mining decisions.
Related terms: SHA-256, Hash, Block Header.