<p>The question is twisted here.Miners has to find nonce with their computation power inorder to solve the difficult puzzle and add the block to blockchain.</p>

CC BY-SA 4.0
2018-09-06T14:55:34.290Z
2018-09-06T14:55:34.290Z
VforVendetta
<p>I think you're confusing terms here.</p>

<blockquote>
  <p>Which variable among the components of the block header is computed</p>
</blockquote>

<p>The block components which are computed (hashed) are all of the components which make up the block header: <strong><em>version</em></strong>, <strong><em>previous block hash</em></strong>, <strong><em>merkle root</em></strong>, <strong><em>unix epoch time</em></strong>, <strong><em>difficulty target</em></strong> (bits), and <strong><em>nonce</em></strong>.</p>

<p><strong>Difficulty</strong><br>
A value which represents how hard it will be to mine a block. Higher difficulty value = harder to solve. The difficulty of the genesis block is 1. All block difficulties are calculated as a ratio to the difficulty of the genesis block.</p>

<p><strong>Proof of Work</strong><br>
When you calculate a proof of work, you must meet the minimum difficulty posed by the network, as you state. This validation step makes sure that the value of the block hash you provide is less than or equal to the <strong><em>difficulty target</em></strong>.</p>

<h2>Example</h2>

<p>To illustrate this concept, you can validate one of the block hashes manually.</p>

<ol>
<li><p>Grab a block (eg. block 3): <a href="https://blockchain.info/block/0000000082b5015589a3fdf2d4baff403e6f0be035a5d9742c1cae6295464449?format=json" rel="nofollow noreferrer">Block 3 in json</a> or <a href="https://blockchain.info/block/0000000082b5015589a3fdf2d4baff403e6f0be035a5d9742c1cae6295464449?format=hex" rel="nofollow noreferrer">Block 3 in hex</a></p></li>
<li><p>Concatenate (in this order, little endian, hex format) the version, previous block hash, merkle root, unix epoch time, difficulty target (bits), and nonce. You’ll see you can copy the first 160 characters from the Block 3 in hex link.</p>

<p>01000000bddd99ccfda39da1b108ce1a5d70038d0a967bacb68b6b63065f626a0000000044f672226090d85db9a9f2fbfe5f0f9609b387af7be5b7fbb7a1767c831c9e995dbe6649ffff001d05e0ed6d</p></li>
<li><p>Run the command:  </p>

<p>$ echo 01000000bddd99ccfda39da1b108ce1a5d70038d0a967bacb68b6b63065f626a0000000044f672226090d85db9a9f2fbfe5f0f9609b387af7be5b7fbb7a1767c831c9e995dbe6649ffff001d05e0ed6d | xxd -r -p | openssl sha -sha256 | xxd -r -p | openssl sha -sha256</p></li>
<li><p>Reverse the output from
<code>4944469562ae1c2c74d9a535e00b6f3e40ffbad4f2fda3895501b58200000000</code> to<br>
<code>0000000082b5015589a3fdf2d4baff403e6f0be035a5d9742c1cae6295464449</code></p></li>
</ol>

<p>And there’s the block hash!</p>

CC BY-SA 4.0
2018-08-29T03:58:32.800Z
2018-08-30T01:32:35.547Z
2018-08-30T01:32:35.547Z
JBaczuk
<p>Which variable among the components of the block header is computed (or rather obtained) to achieve the difficulty posed by the bitcoin network?</p>

<p>Nonce or Previous block hash?</p>

<blockchain><bitcoin-core-development>
Calculate the difficulty of Bitcoin network
Abhijeet Kumar
# Calculate the difficulty of Bitcoin network

(Asked by: username_0 on 2018-08-29)

Which variable among the components of the block header is computed (or rather obtained) to achieve the difficulty posed by the bitcoin network?

Nonce or Previous block hash?

**Tags:** blockchain, bitcoin-core-development


---

## 2 answers

### Answer by username_1 on 2018-09-06. Score: 0 | Accepted answer

The question is twisted here.Miners has to find nonce with their computation power inorder to solve the difficult puzzle and add the block to blockchain.


---

### Answer by username_2 on 2018-08-29. Score: 0

I think you're confusing terms here.

> Which variable among the components of the block header is computed

The block components which are computed (hashed) are all of the components which make up the block header: ***version***, ***previous block hash***, ***merkle root***, ***unix epoch time***, ***difficulty target*** (bits), and ***nonce***.

**Difficulty**  
A value which represents how hard it will be to mine a block. Higher difficulty value = harder to solve. The difficulty of the genesis block is 1. All block difficulties are calculated as a ratio to the difficulty of the genesis block.

**Proof of Work**  
When you calculate a proof of work, you must meet the minimum difficulty posed by the network, as you state. This validation step makes sure that the value of the block hash you provide is less than or equal to the ***difficulty target***.

## Example

To illustrate this concept, you can validate one of the block hashes manually.

1. Grab a block (eg. block 3): [Block 3 in json](https://blockchain.info/block/0000000082b5015589a3fdf2d4baff403e6f0be035a5d9742c1cae6295464449?format=json) or [Block 3 in hex](https://blockchain.info/block/0000000082b5015589a3fdf2d4baff403e6f0be035a5d9742c1cae6295464449?format=hex)
2. Concatenate (in this order, little endian, hex format) the version, previous block hash, merkle root, unix epoch time, difficulty target (bits), and nonce. You’ll see you can copy the first 160 characters from the Block 3 in hex link.

   01000000bddd99ccfda39da1b108ce1a5d70038d0a967bacb68b6b63065f626a0000000044f672226090d85db9a9f2fbfe5f0f9609b387af7be5b7fbb7a1767c831c9e995dbe6649ffff001d05e0ed6d
3. Run the command:

   $ echo 01000000bddd99ccfda39da1b108ce1a5d70038d0a967bacb68b6b63065f626a0000000044f672226090d85db9a9f2fbfe5f0f9609b387af7be5b7fbb7a1767c831c9e995dbe6649ffff001d05e0ed6d | xxd -r -p | openssl sha -sha256 | xxd -r -p | openssl sha -sha256
4. Reverse the output from
   `4944469562ae1c2c74d9a535e00b6f3e40ffbad4f2fda3895501b58200000000` to  
   `0000000082b5015589a3fdf2d4baff403e6f0be035a5d9742c1cae6295464449`

And there’s the block hash!


---

