Questions tagged [block-header]

The block header is a portion of each block in the block chain that identifies the basic parameters of that particular block such as the block version, the time it was generated, the hash of the previous block, and the hash of the transactions in that block.

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23
votes
4answers
4k views

Why don't the timestamps in the block chain always increase?

The timestamps starting at block 145044 are: 145044: 2011-09-12 15:46:39 145045: 2011-09-12 16:05:07 145046: 2011-09-12 16:00:05 // ~5 minutes before prior block 145047: 2011-09-12 15:53:36 // ~...
9
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1answer
27k views

Whats the process of Creating a Block on the BlockChain

have been mining on pools and blindly going a long for the ride of > generating a block Can somebody walk through the process in simple terms of the steps involved in creating a block on the ...
7
votes
1answer
2k views

Calculate hash of block header

I'm trying to calculate the hash of block #502871. This is the block: { "result": { "hash": "00000000000000000020cf2bdc6563fb25c424af588d5fb7223461e72715e4a9", "confirmations": 35, "...
18
votes
4answers
7k views

How can one embed custom data in block headers?

Some mining pool admins put custom data in block headers, like prayers. How do they do that? Where can I see that data for myself?
7
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2answers
2k views

How is it that concurrent miners do not subvert each other's work?

Every time a new block is added on top of block chain, the miners have to restart their work because the next block has to have a proper reference to previous block. Let's suppose that there is some ...
8
votes
5answers
3k views

Why didn't Satoshi make the nonce space larger?

I know Satoshi isn't around to ask anymore, so this might be futile to ask, but I'm hoping someone might have some insight about this. Bitcoin mining typically utilizes an extraNonce (bnExtraNonce ...
4
votes
1answer
2k views

Bitcoin mining: block structure

please note I have made this question previously (link) and I was indicated to visit here. I am writing a program using GoLang to mine bitcoins. It's part of my college conclusion project and likely ...
1
vote
1answer
308 views

How is the difficulty of bitcoin mining propagated?

Let's say the current difficulty is set as finding a hash with 4 leading zeroes; once this is found, a block with this hash is propagated. Every client that receives this block checks that it has 4 ...
25
votes
4answers
71k views

The bitcoin mining algorithm from a programmer's viewpoint

This page: Blocks said mining is actually to solve a mathematical problem, but reading Block hashing algorithm doesn't give much help. I also tried reading bitcoind source code, but reading code takes ...
36
votes
2answers
9k views

Nonce size - Will it always be big enough?

If I understand correctly, the block only has 4 bytes (32 bits) for the nonce. Is it possible for the difficulty to become high enough that there are no nonce solutions? If so, then what options does ...
5
votes
3answers
8k views

Full example data for scrypt Stratum-client

I'm trying to write a Mining client for Scrypt-based mining using Stratum Communication. As of now, I have some trouble verifying all my bit orders and sequences. Hashes I'm generating get always ...
7
votes
1answer
3k views

How does the bitcoin network recover in case of a hash collision in the block hash?

A Bitcoin client has to download the whole blockchain from the P2P network in order to become a full node. A full node is able to determine, if a transaction in the network is valid or not. To ...
5
votes
1answer
2k views

Why the timestamp component of the block header?

What is the reason for the timestamp field in the block header? Surely the nonce should be the only property that changes? Should the nonce reset to 0 everytime the timestamp changes?
4
votes
3answers
366 views

How hard is it to alter a block after it was found?

Once a miner has found a block, how easy it is for him to add or remove a tx included in that very block? Would he have to solve the modified block from the scratch or is there a point he can resume ...
1
vote
1answer
268 views

Do you know any download site for full blockchain header data (6) in CSV ASCII format?

do you know any download site for full blockchain header data (6 variables) in CSV ASCII format ? I would like to enter block header data for every block from No.0 to latest into mining simulator to ...
19
votes
3answers
1k views

How would the Bitcoin protocol be impacted if nodes only stored the blocks they cared about?

Right now, full clients of the Bitcoin network store every block ever generated (while "thin" clients instead rely on a node which does so). This greatly increases first-time initialisation for the ...
5
votes
2answers
2k views

How to create a SPV client?

What are the steps a SPV client takes in order to sync? Connect to a peer Set bloom filter for wallet addresses Download all block-headers since latest checkpoint Request every block again with ...
3
votes
1answer
581 views

How is mining difficulty defined (formula)?

The result of sha256(s) that miners attempt is a 256 bits long number (64-digits hexadecimal number). I understand that this 256bits number should be lower than the target threshold, the target ...
2
votes
2answers
402 views

How often do miners recalculate the merkle root they're working on?

I think that I understood most of the things about Bitcoin but there is still a mystery. We can see on https://blockchain.info/ that there are up to 4/5 new transactions every seconds. My question ...
2
votes
1answer
299 views

Why there is no block index or block height included in the block header?

Why block index or block height is not included in the block header? Do we have to go through the whole chain if we want to know how many blocks are there in a chain? On the other hand, if some blocks ...
2
votes
1answer
389 views

How is the mempool incorporated in the calculation of the block hash?

So I've been reading about how the nonce is calculated. There is one part that I don't get. So there is a mempool, and each node (or mining node) takes a part (or the whole part) of that mempool, ...
1
vote
1answer
196 views

Why do block explorer APIs say the nonce in the block header is 0?

Several block explorers are reporting that the nonce value in many block headers is 0. For example, blockcypher, Why does this happen? Where can I get the actual block headers?
1
vote
1answer
848 views

Why do we need a mining speed above 4.3Ghash/s?

I believe there will be a simple flaw in my understanding somewhere. From what I can tell for any given block you increment a nonce up to 2^32 (4294967296) per second (and the timestamp every second) ...
0
votes
2answers
285 views

How Is Block Assembled?

I think I understand mining well enough, but what I don't get is how the blocks of transactions are assembled. According to this post - What exactly is Mining? - the miners assemble the blocks and ...