Mining nonce

Searching rather than solving a payment

Proof-of-work mining repeatedly evaluates candidate inputs and checks the results against the difficulty requirement. The miner is not decrypting transactions or discovering wallet keys. Changing the header nonce changes the candidate being tested.

The nonce appears in the accepted block so other nodes can reproduce the proof-of-work calculation. Verification does not require repeating all the unsuccessful attempts that preceded it.

References: Monero transaction and block data structures · RandomX algorithm specification

More work than one header field

A 32-bit field has a finite set of values. Miners and pool software can create distinct candidates by changing permitted data in the block, such as reserved miner-transaction space, then continuing their search.

Do not confuse a mining nonce with every other use of the word nonce in cryptography. The secrecy and reuse requirements for signature or encryption nonces come from their own protocols, independently of this public block-header field.

References: Monero transaction and block data structures · Daemon RPC reference

Example

A miner tests the same candidate with nonce values 100, 101 and 102. Each attempt produces a different hashing input, but none is guaranteed to meet the current difficulty target.

References: Monero transaction and block data structures · RandomX algorithm specification

Limits and cautions

A nonce is public block data, not a wallet password or private key. Exhausting the nonce field does not mean a block is impossible to mine. Mining software can change other permitted parts of the candidate to create more work.

References: Monero transaction and block data structures · RandomX algorithm specification