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What is Blockchain Nonce and What Does it Do

What Is Blockchain Nonce And What Does It Do?

Ever since Bitcoin’s initiation in 2009, numerous cryptocurrencies have emerged as more and more investors have become interested in the asset class. Notably, as of the third quarter of 2022, the global crypto market cap already stands at $998.47B.

Many of the cryptocurrencies we have today in the markets use the proof-of-work algorithm that the Bitcoin blockchain first used to add new blocks to the chain. On a proof-of-work chain, miners have to solve complex mathematical problems to validate a block and add it to the distributed ledger that is a blockchain.   

A ‘nonce’, as we will discuss in this post, is an integral part of blockchain cryptography in a PoW chain. Without further ado, let’s jump into our detailed discussion of what is nonce in blockchain, shall we? 

What is a Nonce in Blockchain?

So, what is a nonce in blockchain? Nonce is an abbreviation for the phrase ‘number used once’; as it states, a nonce is a random number that can only be used once. A nonce is only generated for a particular use, such as to modify the outcome of a function run within a cryptographic communication. 

A proof-of-work blockchain like Bitcoin stores the value of a previous block as a hash value for the current block. Because of this, no one can tamper with a block without modifying all following blocks too. Now, what is the purpose of nonce in a blockchain? It can be used to modify the input to a cryptographic hash function on a PoW blockchain. Through this, the task of mining a block acquires the required difficulty level, and also the blockchain is kept secure from hacking attempts.  

The 32-bit string nonce on a PoW blockchain varies with every block added to the chain, so some values can not be put to use again. Once a miner derives the value of the nonce through their mining equipment, they win the right to add the latest block to the chain. 

How Does a Nonce Work in a PoW Blockchain?  

Now that we know what is nonce in blockchain, let’s get into the way a nonce works. The random number that is a nonce is basically used as a counter in the mining process that takes place on a PoW blockchain.

How Does a Nonce Work in a PoW Blockchain
Source| What is the purpose of nonce in blockchain?

When mining, a miner has to try and guess the correct nonce when calculating a block hash. They must guess the valid nonce and add it to the hash of the existing block header, and then rehash this value and compare the outcome to the target hash. When this resulting hash value meets all requirements, a miner’s work is done. 

The miner who is the first to successfully find a valid nonce capable of forming the required block hash gets to add the newly formed block to the chain, and they get rewarded for their efforts.  

Importance of Nonce in Blockchain  

There are many reasons as to why a nonce is important in blockchain, namely:

  • Without testing their hashing outputs with the help of a nonce, miners can not add a new block to a chain. 
  • Finding the ‘golden nonce’, i.e. the nonce that renders a block valid, is how a winning miner is chosen for every round of mining.
  • A nonce is essentially a brute force method for miners to help find the best way to earn rewards on a PoW blockchain. 
  • A nonce therefore supports the allocation of rewards on a PoW blockchain in the form of newly minted native tokens. This in turn negates the possibilities of double-spending of a crypto. 
  • Finally, a nonce signifies the uniqueness of a new block. 

Difficulty in Finding Nonce  

The difficulty levels of nonce estimation is adjusted by a blockchain periodically, depending on factors like the number of miners on the chain, or the certain target of blocks to be verified within a fixed time period. 

As the difficulty level for guessing the nonce is increased, it gets harder for miners to win and add new blocks to the chain. However, this issue can be solved with upgraded computing resources. The right mining hardware will help a miner determine a nonce before others. 

Uses of Nonce  

A PoW blockchain is just one of the many use cases nonces have. They can also be used in:

  • Authentication protocols so as to keep older communications from reprocessing.
  • A nonce can work as an initialization vector in data encryption. 
  • They can also be used to avoid repetition of sequences in encrypted text.
  • Nonces can help in creating and verifying e-signatures. 


To sum it all up, nonces are a big part in the working of proof-of-work blockchains; they play a key role in the addition of new blocks to the chain, and also facilitate a fair rewarding system for miners. If you plan to take part in block mining, ensure that the hardware you use is fully equipped to handle the difficulty levels on the PoW blockchain of your choosing.

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