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What it means and how it is used in Blockchain
What is Nonce?
Nonce, a combination of “number used only once”, is a number used by the Bitcoin mining program. It is included in the block header, so the information is hashed. If the sum of the resulting hexadecimal number matches a value less than or equal to the network’s difficulty level, the miner’s block is added to the blockchain. Another one is opened and the process begins again.
Key points
- A nonce is a numeric value used in a trial-and-error process to add a block to the blockchain.
- The nonce is incremented by a value of one for each attempt made.
- Finding the right combination of nonces and other values in the block consumes significant computing power.
- The nonce is one of the few values that can be changed to generate hashes for the competitive mining process.
Understanding the Nonce
A Bitcoin nonce is a 32-bit (or 4 byte) number used by miners to attempt to generate a valid hash to produce a new block in Bitcoin blockchain. The nonce is one of the fields included in the block header, which also includes:
On the Bitcoin network, participants called miners compete to generate a hash less than or equal to the network’s target hash by repeatedly changing the nonce after each failed attempt.
Hashing refers to the process of applying a Cryptographic hash function to information. The cryptographic hash function is a mathematical operation that takes block data and encrypts it into a unique value, a fixed-length output of hexadecimal characters.
This hash value serves as the block’s cryptographic fingerprint, ensuring that the contents of the block remain unchanged. The nonce is the only variable in the block header that a miner can modify. By changing the nonce, a miner can change the hash of the block and calculate different possible solutions.
For example, this is the previous paragraph sent via a SHA-256 hashing algorithm:
acd691b23cc47b03addf7329b0467c6190e758ee763d7d648af75b5c5ae73e3a
Adding a value of zero (the nonce) to the end of the paragraph gives you a different hexadecimal value:
f4be24818264fdb8d120f7fe04b8b8f8d4359bc7b1a112412fa968aab7acb782
If you change the zero to a one, you’ll get this:
9e3f30005b29927043ecfcec9edf815493326fe2060015fd56ed3213564c7200
This is how the nonce is used by Bitcoin mining programming. The nonce value is increased by one with each attempt until a certain value is reached.
The first miner to find a valid hash under the network’s difficulty target receives the block reward. Their block is broadcast to the network, added to the blockchain, and the process starts again.
Target difficulty is a measure of how difficult it is to find a valid nonce. It is adjusted periodically to maintain a consistent block generation rate.
Extra nonce and timestamp
In a Block Explorer you will find that nonces generally only run into the billions. For example, the nonce for block 841,948 was 1,614,498,317. Block 841,949 had a nonce of 4,218,083,700. A modern mining rig can generate many more hashes in less than a second.
Additionally, the nonce is limited to 32 bits (4 bytes), so it can only go up to just over 4.29 billion. It has to rollover to be useful because hashing is so fast. So, an additional method was created after Bitcoin ASIC miners started breaking through the blockchain. Another number, called an extra nonce, is randomly generated and used in Coinbase’s data field. This value is added to the coinbase transaction space, which modifies the Merkle root.
The Merkle root is part of the block header, so the hash of the block header changes. The extra nonce and the nonce are both manipulated to try to find the solution. If a solution cannot be found using any of these, the mining program allows miners to change the timestamp. The combination of these three values allows the blockchain to maintain its goal of mining a block approximately every 10 minutes.
What is the meaning of the phrase for the Nonce?
“Nonce” combines the phrase “number used once”. It is used by the Bitcoin blockchain to help generate a hash value when mining a block.
What is the concept of nonce?
A nonce, in blockchain terms, is a number used once. As for its use on blockchain, it is a number that increases sequentially with each attempt to generate a hash that meets the network’s difficulty criteria.
What is an example of a nonce?
The best example of a nonce is a nonce used to mine a block. The nonce used in block 841,954 was 3,983,795,221. This doesn’t mean that the miner only took 3.98 trillion attempts – it probably repeated itself several thousand times and was used in combination with the extra nonce and timestamp variable entries. Being a 32-bit number, the nonce can only increase to just over 4.29 billion.
The bottom line
In Bitcoin mining, miners compete to find a nonce that meets the network’s difficulty criteria. The information in a block header is sent through a hashing algorithm, resulting in a value that must be less than or equal to the network’s difficulty target.
On each attempt to reach the goal, the nonce is increased by one. If it exceeds the 32-bit limit, it is rolled over and the additional nonce and timestamp are used in conjunction with it until a miner succeeds.
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