Questions tagged [proof-of-work]

This tag should be used for questions regarding how Proof of Work works and Proof of Work algorithms. Proof of Work is a scheme where a 3rd party can verify that someone performed at least a certain amount of work to produce something. This is used in Bitcoin mining.

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What is meant with 'the highest PoW'?

What is meant when the nodes select the chain with the highest cumulated PoW? How is the highest highest PoW calculated? I thought the concept itself is called PoW.
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Permissioned or Permissionless blockchain? Which one is PoS more adapted for?

Since in proof-of-stake (PoS) there is no mining process, according to functionality of permissioned and permissionless blockchains, which type is PoS more adapted for? In the other words, is a PoS-...
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is the proof-of-work for safety or efficiency?

i am reading the proof-of-work (aka: pow, target threshold, difficulty, etc.); my understanding is that pow adds a requirement to validate block headers, so that both benign and malign nodes need a ...
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51 views

Ethereum's PoW difficulty

Bitcoin's block time is about 10 minutes while that of Ethereum is 15 secs. Both are using PoW at this moment, right? How come Ethereum's block time is so short compared to Bitcoin? Is hashing a lot ...
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113 views

Is the bitcoin blockchain really non-corruptible? [duplicate]

Some people say that proof of work is better than proof of stake, because it's not possible to rewrite the whole blockchain on-spot. One would need to "re-mine" everything. But I think this is not ...
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2answers
231 views

Why are blocks in a permissioned blockchain linked together?

My question: Do the blocks in a blockchain without proof-of-work (i.e. a permissioned blockchain) have to be linked together via a cryptographic hash? Longer version of my question: (Please correct ...
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53 views

What are the hashes that miners need to do to create a block? [duplicate]

I’m bit stuck in the concept of mining. What are the hashes that need to be created in each block and the chain? Let’s say that we have block A - B - C forming a chain. One source said that we need ...
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105 views

When does a node mark a transaction as confirmed or unconfirmed?

As new transactions are broadcasted, the nodes keep them in a pool of unconfirmed transactions. One node will add it to a block as soon as it finds a proof of work. At the same time many other nodes ...
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190 views

How does bitcoin implement checkpoint mechanism to finalize the blockchain history?

I read in Peercoin whitepaper that to prevent large blockchain reorganization, bitcoin also implements checkpoint mechanism which finalizes the blockchain history. Can you explain how exactly bitcoin ...
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80 views

Source of entropy for PoW hash

How does bitcoin do it to generate an (upredictable) hash in each new block with sufficient randomness so that no one can precompute it?
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When does client decide to stop/cancel proof of work algorithm?

I have been reading about bitcoin and blockchain in the last few days, but I have something I don't clearly understand. The "proof of work" may take a long time for a simple node to guess, but if we ...
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How many proof-of-work algorithm exists for crypto currencies?

How many proof-of-work algorithm exists for crypto currencies ? We know PoW in Bitcoin and Etherium are different. Is there any other algorithm used for crypto currencies ?
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Is there any link between Bitcoin's PoW and BFT?

As per Bitcoin's documentation, the consensus mechanism in Bitcoin Blockchain is based on PoW. Thus, any miner node successfully computing the hash as per difficulty is eligible to mine a block and ...
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789 views

What prevents a miner from faking nonce hash

What exactly prevents a miner from presenting a random nonce hash of the block with enough zeroes at the start to get chosen? How is the new hash verified by the other nodes? Since as I understand ...
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631 views

Bitcoin Mining Computational Power [duplicate]

1/ I do not understand why bitcoin mining is random when hashing is deterministic. reference : https://en.bitcoin.it/wiki/Nonce Can the mining pool with the most mining power always win? What value ...
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3answers
1k views

Difference (if any) between proof-of-work in mining bitcoin vs verifying transaction

I'm trying to understand the proof-of-work idea for verifying a transaction. I think I understand why proof of work is needed to verify transactions (essentially to prevent spoofing/double spending ...
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1answer
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What is the algorithm that adjusts the difficulty of the proof of works in a proof of work based cryptocurrency? [duplicate]

For instance, Bitcoin has a proof of work based consensus algorithm, it's how Bitcoin chooses a node to create the next block in Bitcoin's blockchain. In this way the network is in consensus about the ...
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2answers
84 views

Bitcoin mining process-the leading zeros before the hash-how is the mining puzzle solved exactly?

Can someone please explain: In Bitcoin proof of work, mining is done to create and validate new blocks. Who becomes the sole block producer is subject to winning a "mining puzzle". As I understand, ...
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48 views

Bitcoin Orphan blocks - short question about the “time lag” factor and proof-of-work “size”

"However, it is possible that two miners produce a block at a similar time. This situation occurs because the acceptance of the blocks into the blockchain by the nodes of the blockchain network ...
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Beneficial proofs of work [duplicate]

I'm new to this community and a Bitcoin novice. I believe to have understood the concept and purpose of proof of work but also, that the high energy consumption of proofs of work is a major problem ...
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180 views

Mining Probability

Assuming two miners have a (1/x) chance of finding a block over some time period, is the probability of both miners finding a block within that period simply (1/x^2)? More generally, would n miners ...
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If all Proof of … systems use mining

I understand how Proof of Work (PoW) works now, and am beginning to look at different Proof of ... systems like these: Proof of Stake Proof of Ownership Proof of Existence Proof of Space From what I ...
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Is it possible to accurately map hashing power to network size?

Let's say we have a network with n nodes in it. Is it possible, when the hashing power of the network is calculated after a proof-of-work, to accurately estimate n with an algorithm taking the ...
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How is the amount of proof-of-work invested in a chain calculated?

The bitcoin whitepaper (page 3) states The majority decision is represented by the longest chain, which has the greatest proof-of-work effort invested in it. I could not find how exactly this ...
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What is the reason to pay miners “monetary rewards” for mining process?

Is it correct to say that: In Bitcoin, it is crucial to incentivize miners by monetary reward, because mining process has significant monetary cost (energy/electricity cost). ? otherwise, mining ...
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70 views

What would happen if PoW cost were drastically reduced or eliminated?

Assuming Bitcoin had a different method for selecting winning nodes and controlling block time creation, please describe step-by-step how the Bitcoin network would be vulnerable to various attacks. ...
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58 views

Why this alternative method to mining will fail?

From what I understand, we need mining to validate the block, we need the proof of work to limit the number of miners can add a block, and we need the block interval to give time to the new block to ...
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83 views

Proof of Work: email versus bitcoin

I have read "Hashcash is a proof-of-work algorithm that requires a selectable amount of work to compute, but the proof can be verified efficiently. For email uses, a textual encoding of a hashcash ...
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23 views

What other proof methods are there? [closed]

I am familiar with the proof of work method and a little with the proof of stake method. Is there any more methods that are out there and how do they work?
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218 views

Difference between Hashcash proof of work algorithm and Ethash proof of work algorithm?

Understand that each proof of work algorithm has its pros and cons. Difference between Hashcash proof of work algorithm and Ethash proof of work algorithm? Nathan Aw
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62 views

How do offchain transactions get validated/confirmed whilst using Lightning network?

How do offchain transactions get validated whilst using Lightning network?
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How is mining associated to blockchain transactions?

I know how mining works and how transactions are added to the blockchain. What I don't understand is the association between the two...if any. I've read a few times about how a cryptocurrency ...
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1answer
609 views

Block Hash and Nonce generated by GenesisH0 python script is incorrect

After running GenesisH0 python script to generate the Genesis block for a local testnet (using v0.15.1), I got the following results. merkle hash: ...
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149 views

Proof of Work and Proof of Stake - Competitive advantage

It is said that Proof of Stake will be the mainstream consensus mechanism in the long run. Regarding the nature perspective I totally agree. But it has been rumoured that Proof of stake is more ...
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1answer
26 views

randomly assigned pow?

in Bitcoin, every node solves the POW puzzle. instead, are there cryptocurrencies where a random group of nodes is chosen (before block creation), and only that group solves for the puzzle?
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Where can i find proof of work in Electrum(light weight bitcoin) source code?

Hi does anyone knows where can i find electrum's proof of work in the source? https://github.com/spesmilo/electrum
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Review of “equitable” proof-of-work systems

One major criticism against usual SHA-based proof-of-work systems in main cryptocurrencies (except the ecological concerns) is the fact that, years after years, it's more and more dominated by a ...
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Miner modify pending block (not yet on chain) and successfully solve the PoW

For example, I pay a cup of coffee with bitcoin, and later remove that transaction from the pending block that is not yet on chain. After 10 mins, I successfully and luckily solve the PoW problem, and ...
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204 views

Hashcash proof of work bitcoin sha256

I'm looking for a program or something to run from the terminal in mac. That does the same thing as the program found here. http://www.blockchain-basics.com/HashPuzzle.html?nonce=221 What I'm looking ...
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2answers
159 views

How to secure new public proof of work blockchain?

I am fairly new to the bitcoin and blockchain technology and have recently started reading about it. So my understanding and the question bellow may not be very accurate. As I have understood so far, ...
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1answer
69 views

separating proof of work from mining possible?

I (think to) understand that proof-of-work is the process through which transactions are verified and the health of the network is being ensured. I also (think to) understand miners get bitcoins for ...
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1answer
147 views

Hash-based crypto-currencies?

What are the most famous crypto-currencies which use repeated hashes as proof-of-work? What are the other proof-of-work methods?
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237 views

Sample proof of work in Ruby, what am I doing wrong?

Given the following block, how do I verify the proof of work? I got this data from bitcoin-cli getblock and parsed in to a Ruby hash called data: {"hash"=>"...
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1answer
22 views

How a transaction is permanently accepted by the blockchain?

If a miner A creates a block containing a transaction A and a miner B creates a block NOT containing the transaction A about at the same time, then some of the other miners will first receive the ...
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0answers
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what prevents a miner from adding a false transaction to a block and then adding it to the block chain in PoW? [duplicate]

Here is what I understand, the step to PoW are: step 1:Miner select some transactions from its mempool. step 2:Miner tries to create a block and then broadcasts it if successful. step 3:Other ...
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118 views

How often should a mining pool be notifying workers about new work (cancelling current jobs)?

I'm trying to get a handle on the Stratum mining pool protocol. If I set up a mining pool client, I will initially get something to work on. Let's say it takes me a while (e.g. an hour) to solve the ...
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1answer
67 views

What was the first transaction which resulted in the very first bitcoin being mined [duplicate]

OK, so I understand that bitcoin in introduced into the system when mining is performed. And mining is a process of adding transactions records to the bitcoin chain of blocks. And transaction (...
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3answers
467 views

After sending/flooding transactions, how do we know that a specific transaction is on all nodes?

In the book "Mastering the Blockchain" by Imran Bashir, it says that a transaction's life cycle is the following: A user/sender sends a transaction using wallet software or some other interface. ...
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318 views

Question solved by bitcoin miners [duplicate]

What computational questions are solved by bitcoin miners and what is the computational complexity of one instance of this question. Essentially, how would someone program an application for bitcoin ...
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1answer
43 views

Validation methods beside POW etc

Are there other concepts for the validation of the next added block to the blockchain beside POW, POS etc.? Of cource there are, but is there a methode that is shining out of the mass? A methode that ...