Nonce meaning refers to a number or value that can only be used once. Nonces are often used on authentication protocols and cryptographic hash functions. In the context of blockchain technology, a nonce refers to a pseudo-random number that is utilised as a counter during the process of mining.
For instance, Bitcoin miners need to try and guess a valid nonce as they perform multiple attempts to calculate a valid block hash. When competing to mine a new block, the first miner to find a nonce that results in a valid block hash is granted the right to add the next block into the blockchain. Furthermore, he or she is rewarded with block rewards for validating the block.
The process of mining consists of miners performing a wide variety of hash functions with many different nonce values until a valid output is produced. If the hashing output of a miner falls below the predetermined threshold, the block is considered valid and is added to the blockchain. If the output is not valid, the miner keeps trying with different nonce values until the miner can successfully return a valid output.
Bitcoin and most Proof of Work systems would require miners to employ a trial and error approach to guess and output nonces until they reach a valid one. A trial and error approach is needed because the probability of guessing a valid nonce is close to zero.
To ensure that blocks are constantly generated, the average number of hashing attempts is automatically adjusted by the protocol. This allows blocks to be generated every 10 minutes. This is known as difficulty adjustment and is what determines the mining threshold, which is how many zeros the block hash needs to start with to be considered valid. The difficulty in mining a new block is directly proportional to the amount of hashing power (hash rate) committed to a blockchain system. With more hashing power dedicated to the network, there will be a higher mining threshold, hence more computational power is required to be a competitive and successful miner. Conversely, a drop in the number of miners will cause the threshold to drop, so less hashing power will be required to mine.
In conclusion, nonce meaning is the number or value that can only be used once, and in blockchain, miners will have to successfully guess the value of a nonce to grant them the rights to be a validator in the network.
