What Is the Difference between a Nonce and an Extranonce?
The nonce is a 32-bit field in the standard block header that miners iterate on to find a valid hash. The extranonce is a variable-length field contained within the Coinbase transaction, which itself is part of the Merkle Root.
When the 32-bit nonce is exhausted, the miner changes the extranonce. This modification creates a new Merkle Root, which in turn creates a new block header and allows the 32-bit nonce search to begin anew.
Glossar
Block Header
Genesis ⎊ A block header, fundamentally, encapsulates metadata pertaining to a specific block within a blockchain; it serves as the block’s identifying signature and is critical for maintaining chain integrity.
Extranonce
Definition ⎊ Extranonce is a variable field included in certain cryptocurrency mining communication protocols, allowing miners to rapidly adjust block header data to find a valid nonce without reprocessing the entire transaction set.
Nonce
Function ⎊ A nonce, short for "number only used once," is a crucial component of the block header in Proof-of-Work blockchains.
Standard Block Header
Genesis ⎊ A Standard Block Header initiates blockchain functionality, encapsulating critical metadata defining the chain’s origin and initial state, serving as the immutable root from which all subsequent blocks derive their validity.
Nonce Search
Process ⎊ The nonce search is the core computational process in Proof-of-Work mining, where miners iteratively vary a random number, the nonce, within a block header until the resulting hash meets the network's current difficulty target.