Questions tagged [block]

This tag should be used for questions related to Bitcoin blocks

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42
votes
6answers
21k views

Why is downloading blocks taking longer and longer?

First off, this really needs to get fixed. I'm downloading blocks for at least 8 hours now, and it's still not done. I know the problem of having to download the entire block chain is being worked on, ...
18
votes
1answer
7k views

What is the expected time until the next block is found?

https://bitcoin.stackexchange.com/a/3908/659 says: Luckily, you'll only have to wait five minutes on average for a block to be found (blocks are one every ten minutes, so the expected delay until ...
15
votes
3answers
5k views

What is the number of transactions in a block?

What determines the number of transactions that can be validated in a block?
15
votes
4answers
15k views

Why does each block store a Merkle root?

I understand how a Merkle root is calculated and stored in the block. But how do miners verify a transaction using the Merkle root? Here are 18 conditions that verify a transaction. None of them uses ...
13
votes
2answers
10k views

Why can we have small fractions of a Bitcoin?

I didn't study the inner workings of Bitcoin (yet), but already since when I just started using it, I wondered why a Bitcoin can be split up in parts. Because there is a limit on the amount of Bitcoin ...
9
votes
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 ...
25
votes
1answer
14k views

When a block is “discovered” how is the nonce determined?

I know that a block is based on a random number called a nonce, but if that number is random and unknown to the miner, how is that number actually verified as the correct nonce and not some arbitrary ...
13
votes
3answers
7k views

What is the exact formula for calculating transaction fees?

According to the Wiki: If the blocksize is more than 250 kB, transactions get increasingly more expensive as the blocksize approaches the limit of 500 kB. Sending a transaction when the blocksize ...
4
votes
1answer
1k views

What is a block?

I know bitcoin has a block chain that is from my best representation a list of blocks. I know the block holds many transactions. But i'm still very much lost as to what a block is and how a block can ...
6
votes
2answers
2k views

Why does the blockchain need blocks?

I think I understand the main parts of the Bitcoin blockchain. While I was explaining the concept to my girlfriend she asked me why groups of transactions are actually stored in a block? Every ...
7
votes
2answers
2k views

When does a miner decide to stop collecting transactions and start calculating hashes to try to win?

I am confused about whether a miner chooses to wait for more transactions (more fees) or starts as soon as it receives the first transaction from the network. Once a miner has started calculating the ...
12
votes
2answers
727 views

Is it possible for the network to stop finding valid blocks?

The hashing problem is by design computationally hard, because SHA-256 hashes are for all intents and purposes random strings with no direct link to their inputs, and there's no (known) way to ...
15
votes
1answer
1k views

What happens when a miner does not claim all fees/generated coins?

Suppose that a miner for some reason has the generation transaction of their blocks not take all the possible coins. This can happen for a variety of reasons, almost all of which are bugs: An off-by-...
6
votes
2answers
423 views

Do transactions affect the discovery of a block?

When a miner creates blocks, do transactions in that block affect the result? For example, if a miner creates a block, but now a new transaction is broadcast on the network, will the miner stop ...
15
votes
2answers
2k views

What's the purpose of a maximum block size?

Bitcoin has a maximum of 1 MB of transaction data in each block. Why is this limit present? When was it added? Was it intended to be temporary?
15
votes
1answer
3k views

Bitcoin Block Size - What are the rules?

What is the maximum size a block can be? Is there a minimum size? Can you have a block with 0 transactions included?
14
votes
2answers
5k views

How do you make a Genesis block?

What is involved in creating a genesis block? What makes it different from the other blocks in the chain.
11
votes
2answers
2k views

Two blocks, two transactions, same hash

Would a block containing a transaction with an identical hash as a previous transaction be considered valid? That is, if someone made a transaction for generating Bitcoins and solve two blocks with ...
3
votes
2answers
357 views

Energy to confirm one block?

What is the minimum energy (or CPU operations) required for someone to confirm one block on their own, to launch a double-spend attack? How can I calculate this from the current difficulty or ...
0
votes
2answers
245 views

At which point and how does the miner who successfully solved hash get coins? [duplicate]

When miner creates a valid block he broadcasts that to the network. It can happen that someone else did the same. So we have half nodes think that chain+A is correct, and other half that it is chain+...
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 ...
16
votes
3answers
7k views

How to calculate new “bits” value?

Every 2016 blocks one needs to calculate new bits value. What is the formula to calculate it?
13
votes
1answer
9k views

How to get a bitcoin address's balance?

I know blockchain.info has an API: https://blockchain.info/q/addressbalance/134dV6U7gQ6wCFbfHUz2CMh6Dth72oGpgH gets the bitcoin address's balance,but it's not open source and must connect to the ...
7
votes
2answers
3k views

What is chainwork?

If I run the RPC call getBlock on the bitcoin-qt client it gives me field called chainwork containing a hash. I cant find any information what this value is about. Request: getblock ...
21
votes
2answers
4k views

What are the arguments for and against the increase of the block size limit?

Can someone give a quick point by point list, what arguments the proponents and opponents of increased blocksize have for their case?
11
votes
1answer
5k views

What is the magic number used in the block structure? [duplicate]

What is the Magic no used in the block structure, why is the value always 0xD9B4BEF9 and what is it used for ? Thanks
3
votes
1answer
332 views

How is network time enforced?

I've seen how nodes gather network time data, but how is it enforced in the blockchain? Are all of the timestamps digitally signed and included in the block as proof?
3
votes
1answer
1k views

Pruning the branches in Merkle Tree

In Merkle tree, leaves are actual transactions and internal nodes are hash of their childrens. In the Bitcoin paper, Satoshi talks about pruning branches in the Merkle tree to save storage space. ...
12
votes
1answer
3k views

Has any illegal data been saved in the Block Chain?

Has any illegal data been saved in the Block Chain, such as an illegal number, or illegal prime?
10
votes
4answers
6k views

Which is the relation between transactions and blocks?

I don't quite understand the relation between a transaction and a block. I imagine it as a list of blocks, and each block having a list of transactions but I have some doubts. When I do a transaction....
7
votes
2answers
1k views

What would happen if two blocks had the same hash?

Consider the following scenario: January 2016 block A gets submitted. Its hash is 0001010. January 2017 block B gets submitted. Its hash is also 0001010 (collision). 10 minutes later, block C gets ...
2
votes
1answer
344 views

Will old accepted blocks ever be removed?

Or are they kept forever such that the chain from the Generation Block will always remain verifiable?
2
votes
2answers
153 views

testnet3 frequent tx malleability

Related How confirm my own doublespend transaction got confirmed This is not about double spends and I believe that the related question is not about double spends ether! On bitcoin's testnet3 I am ...
4
votes
1answer
329 views

Which is the smallest hash that has ever been hashed?

Let's assume, the hash 00000000000000000024c0bdbec66a889778c00bc69be0a96cbbd98b75c3ce09 of block #499644 is smaller than 0000000000000000002d429f39afec70c938e888c3417d690bbc85e83529991c of block #...
3
votes
1answer
2k views

How to calculate the BIP34Hash?

I know this going to be a repeat question, however I am still puzzled with the implementation of the BIP34 especially where it come to its hash. Referring to the chainparams.cpp at github : https://...
3
votes
1answer
2k views

Which cryptocurrency has the smallest block time?

What is the lowest block time of any cryptocurrency? I don't mean the time of an individual block, but the target time per block. What is the shortest reasonable block interval?
3
votes
1answer
639 views

After Segwit Activation, what is the largest block size possible?

The code says MAX_BLOCK_SERIALIZED_SIZE = 4000000, but that is actually not a actually consensus rule as stated here: https://github.com/bitcoin/bitcoin/issues/10289 The actual consensus rule is ...
1
vote
1answer
176 views

Which elements of a block are hashed?

Other than the previous block hash and nonce data, which elements of a block are concatenated in order to be hashed?
10
votes
1answer
3k views

Where is the UTXO data stored?

When a new transaction is received it is added to the memory pool (after checking for conflicts). While mining, only the transactions which are in the pool are considered. What happens to the ...
20
votes
6answers
2k views

What encourages Bitcoin miners to relay blocks?

Lets say I'm mining bitcoins, and I've just received a new block that someone else has mined. What encourages me to send that block to anyone else. I can understand how the original miner wants to ...
3
votes
1answer
1k views

given a json of a block, how do I calculate its hash?

Here is the genesis block with its hash. How the hash was calculated? { "hash":"000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f", "ver":1, "prev_block":"...
15
votes
1answer
1k views

How can a non-miner store data in the block?

If I am not a miner and would like to put arbitrary data in the block chain, is there currently any method or protocol to get a miner to add it for me?
10
votes
3answers
7k views

What are the equations to convert between bits and difficulty?

If we take block hash 0000000000000006770c3806960539ca83a24facbd99ea212f37f2a0e6a5629a for example. The difficulty as a 32 bit float is 50810339.04827648. The difficulty in bits as an unsigned 32 bit ...
7
votes
3answers
3k views

How can I recover from a corrupted blkindex.dat on Ubuntu 12.10?

I've installed Bitcoin-Qt after a clean WUBI install, and installed Bitcoin-Qt directly. Now it suddenly says "Error loading blkindex.dat". I assume my blkindex.dat file is corrupted, and I tried ...
7
votes
2answers
2k views

How to prevent a miner from stealing another miner's block?

Many articles only contain a phrasing like A miner A solves the hash problem and gives the result to the network to check. Once a majority of the network confirms, A gets the reward. But how does ...
5
votes
3answers
2k views

Getting orphaned Blocks from the Blockchain

I'm very interested in doing some analysis of orphaned blocks, but to do so I'd have to have a good way of accessing them. Blockchain.info seems like a good place to start but I don't want to abuse ...
4
votes
1answer
1k views

JSON-RPC getwork data field

I recently tried playing around with the getwork command for JSON-RPC and I'm trying to understand what I got out of it. According to the API Call List wiki entry, the "data" field should contain the ...
3
votes
1answer
1k views

Verifying Bitcoin ownership

Suppose Alice has 30 bitcoins from David. Now Alice wants to transfer amount 20 bitcoins to Bob. Now, Alice creates a transaction with Bob's bitcoin address. To prove authenticity and integrity, ...
12
votes
2answers
2k views

Who mined the infamous block 364422?

Block 364422 contains a transaction that takes a long time to verify. This transaction design demonstrates a way a denial of service attack could be executed. This prompted Gavin Andresen to propose ...
6
votes
1answer
207 views

What happens in detail, when Bitcoin Core verifies a block during synchronization?

Since version 0.10.x, block headers are acquired separately, and therefore download is not delayed until previous blocks have been verified. Previous questions about synchronization mention that the ...