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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How does proof of work inspire trust when the work is just guessing?

I'm struggling to understand the value added by machines guessing at inputs to create a hash below a target value in order to produce a proof of work. I understand the proof of work is somehow ...
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2answers
38 views

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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1answer
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What hash algorithm is used in Bitcoin Cash?

I know that bitcoin uses hashcash as PoW algorithm, Ethereum uses EtHash and Litecoin uses Scrypt. But I didn't found anywhere the PoW algorithm used in BitCoin Cash, does it uses hashcash too?
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319 views

Byzantine Fault Tolerance Threshold of Bitcoin: 1/2 or 1/3? (Edited)

According to this answer: https://bitcoin.stackexchange.com/a/58908/41513 a Byzantine Fault Tolerant (BFT) consensus threshold is 1/3. On the other hand, there is a common belief that Bitcoin network ...
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1answer
39 views

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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1answer
169 views

Partial Proof of Work in Pools

Technically speaking a full PoW solution is one whose hash value is below a certain threshold value say V. It is not equivalent to saying that the hash value must begin with say X number of zeros (...
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1answer
208 views

Is this calculation of mining probability using the Bernoulli trial formula accurate?

I'm trying to understand the formulas for successfully mining a block (without a pool) based on hashrate over time (i.e. to chart the probability of finding a block at various historical points ...
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1answer
69 views

Proof of work: average number of tries to create a block

First, I'm sorry if I'm asking a stupid question. I'm just trying to understand bitcoin. I'm reading the Ethereum white paper, and I couldn't understand this sentence about proof of work: At the ...
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1answer
88 views

Why haven't a large number of cryptocurrencies copied Primecoin's mining algorithm? [closed]

According to my understanding, generating an ever-growing list of prime numbers benefits mathematics and society in some mysterious way. Given this, why have more recently created proof-of-work ...
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1answer
261 views

Is “Proof-of-work” a subset of “Byzantine fault tolerance (BFT)”?

Can we say that Proof-of-work is a type of Byzantine fault tolerance (BFT) ? In other words, is PoW a subset of BFT ? Or they are two different categories? Please note that there is a similar ...
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1answer
46 views

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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2answers
82 views

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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What is resource of mining rewards

How the coins must be paid miners for mining process is provided? One of resources may be transactions fee. Is there any other resources for proving reward of miners?
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1answer
101 views

What is the “main” difference between consensus mechanism of Bitcoin and Ethereum?

Bitcoin and Ethereum both use proof-of-work (PoW) consensus mechanism. One of differences between Bitcoin Pow and Ethereum PoW is difficulty level, meaning that while in bitcoin block generation rate ...
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2answers
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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4answers
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PoW 51% attack vs. BFT 1/3 attack?

So from what I understand, Bitcoin's PoW is prone to 51% attack, but as a distributed system it is also prone to BFT's 1/3 attack right? I think it's mathematically proven that in a distributed system,...
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1answer
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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2answers
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Blockchain validation process is linear?

I've read at a few places that the nodes validate transactions in a linear fashion, i.e. after node A validates, then node B, etc. (which is also the reason, as claimed by many, why blockchain suffers ...
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1answer
37 views

Security via Proof - of - Work

I am reading Satoshi's original paper, merely for the sake of understanding the concept. I have minimal computer science background (some), mostly just mathematics. In Section 4. Proof of Work of ...
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2answers
140 views

What happens if full nodes don't check for double spends or deliberately lets a double spend TX pass and then this full node relays the transaction?

I am studying about Bitcoin and Blockchain tech via the Princeton crypto course, and it mentions that Full nodes do the following checks : i)transaction is valid with the current blockchain, ii)...
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1answer
57 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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1answer
75 views

Why not to mine more efficient?

I'm a kinda newbie here. But this is what I completely can not understand. If every single miner have to 'arrange' transactions and then compute a SHA-256 function of a given memory chunk, and if ...
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1answer
45 views

Is it a problem that miners participate in a pools? [duplicate]

I am talking about miners centralization with large pools. Is it a problem? I think there are some possible ways to prevent miners from pooling. For example add miner signature to the block header, ...
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1answer
56 views

On a low level, how are long chains kept secret and later broadcast during 51% attacks?

I've been reading about the vulnerabilities of PoW crypto, and there's a part of it that I don't understand. Suppose I wanted to stage a 51% attack on Bitcoin (not really feasible, but bear with me). ...
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2answers
82 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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1answer
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What prevents similar time-warp attacks in Bitcoin as happened to Verge?

Right now (may 2018), Verge (an altcoin with proof of work) was attacked by time-warp attack. More can be read here https://blog.theabacus.io/the-verge-hack-explained-7942f63a3017 What exactly ...
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1answer
112 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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1answer
170 views

My coin - Proof-of-Action

I am writing a project on cryptocurrencies. As a part of this project, I thought of a new token for web services exchange. I tried to combine PoW and PoS and here is what I have. I called it Proof-of-...
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1answer
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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1answer
643 views

How does scrypt pow work?

Bitcoin's pow is sha256, the hash of header is taken and check against a given target to see whether it is smaller than the target, this can be easy seen as block hash starts with zeros. But how does ...
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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 ...
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2answers
216 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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227 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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2answers
757 views

Why miners solve a puzzle in proof of work

I am new to block chain, In PoW, I know a puzzle is given to the miners to solve and the miner who solve the puzzle and find the nonce first will create the block. But I don't understand why there is ...
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1answer
102 views

How can one blockchain with the same block heigth as another, have more Proof-of-Work

I am reading Andreas M. Antonopoulos's book and In chapter 10 - Assembling and Selecting Chains of Block he writes: Under most circumstances this is also the chain [main chain] with the most block ...
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1answer
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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1answer
91 views

What happens to the blockchain after the miner wins the puzzle?

I have some problems understanding the flow of consensus mechanism, so far I know, In PoW when validating a transaction the miners will compete with each other to solve a puzzle, the miner who find ...
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0answers
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
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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1answer
53 views

The “work” in proof of work

How does proof of work function? Why does the "work" in proof of need to have zero utility for the economics of the cryptocurrency to be viable.
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How to protect the early stages of a proof-of-work application?

For a given cryptocurrency or other blockchain application, proof-of-work provides intrinsic security in the algorithm itself that makes it unlikely that someone can attack the network unless they ...
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1answer
60 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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1answer
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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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1answer
43 views

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
602 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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1answer
240 views

How does Proof of Stake prevents dishonest behaviour compared to PoW?

I know that in Proof of Work (PoW) once a node has found the solution (the nonce) they announce it to the network. Then the rest of the nodes can easily verify the correctness of the block hash and ...
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0answers
192 views

How to check that Genesis Block has valid proof of work using CheckProofOfWork() function?

I have been learning the ins and outs of the bitcoin source code over the past 3 months but I can say I have not fully mastered it yet. I wish to understand how the genesis block is validated using ...
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2answers
389 views

Is Proof-Of-Work simply a decentralized clock?

I have not seen anyone explain Proof-Of-Work this way, so I thought I'd share it here, I'd be curious to know if I'm completely off. It seems to me that PoW is simply a distributed decentralized ...
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1answer
187 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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1answer
147 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 ...