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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Is it always possible to find a number whose hash starts with a certain number of zeros?

As I understand it, proof of work requires nodes to "scanning for a value that when hashed, such as with SHA-256, the hash begins with a number of zero bits" ([bitcoin paper])1. Specifically,...
-1 votes
2 answers
91 views

Is solo mining solve block as same as pool mining?

Guys i want to ask tht if solo mining has the same strategy as same as pool mining I mean the way they guess the block hash is it the same or not?
206 votes
10 answers
116k views

What exactly is Mining?

I have heard that mining is for people with ready hardware and blah blah blah... But what exactly is it? Does it operate like real mining? I mean, people talk about it like you are physically mining.
1 vote
2 answers
199 views

Why is Bitcoin inefficient? Would other cryptocurrencies do better if they were as popular?

I'm new to blockchain stuff. I have few questions. Why are Bitcoin fees are so high compared to Litecoin or other currencies? Why does Bitcoin use so much computing power (more than Ireland)? I heard ...
3 votes
0 answers
427 views

Probability of Orphaned Blocks

This is a question regarding the probability of orphaned blocks depending on the block interval. I am using Bitcoin vs Litecoin as an example. Assuming equal hash rate and number of transactions, ...
0 votes
1 answer
178 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 ...
7 votes
1 answer
213 views

Can we measure bitcoin's accumulated work in terms of entropy (in bits) directly rather than expected number of hashes?

The Background Bitcoin tracks chain work by counting the (expected) minimum number of hashes it would take to create a chain of the same number of blocks and same difficulty steps[1]. Naturally, ...
9 votes
3 answers
5k views

Probablity Distribution of mining

What is the probability distribution of solving a block, given the same difficulty. So if I try to mine multiple times using the same difficulty, is it normal distribution with mean of 10 minutes? ...
0 votes
2 answers
41 views

Are the blocks produced by different nodes in the network comparable in terms of the order of transactions contained in them?

Having a transaction from person A to B and another transaction from person C to D that both took place in more or less the same time I assume that there might be a situation in which different nodes ...
19 votes
3 answers
12k views

What is proof-of-work?

Please explain the proof-of-work concept. And how does it relate to Bitcoin mining in general, and to the proofs of work (aka shares) of mining pools?
5 votes
5 answers
1k views

Has anyone proposed a human only proof of work system?

There have been suggestions of proof of work requirements that exclude GPUs or ASICS (or try to) but I was wondering if anyone had suggested a proof of work that is not suited to being solved by ...
1 vote
0 answers
54 views

What are the differences between POW, RPOW and hashcash?

What are the key differences between Satoshi’s Proof-of-Work, Hal‘s Reusable Proof-of-Work and Adam Back‘s hashcash?
1 vote
0 answers
50 views

How does mining work on a technical level?

I want to make a scrypt/sha256 miner for Bitcoin and altcoins in C to learn more about how mining works in Bitcoin, altcoins and learn more C. getblocktemplate gives some data that is needed for ...
0 votes
1 answer
59 views

Bitcoin network: data-intensive or compute-intensive system?

Is it more accurate to consider the Bitcoin network a data-intensive system due to the massive amount of data that must be stored by miners, or instead, a compute-intensive system due to the PoW and ...
0 votes
1 answer
101 views

Potential fork from genesis block using enormous computational power

51% attacks are commonly discussed where one entity could potentially mine blocks ahead of the network. The assumption is that the attacker manages to acquire 51% of computational power. However, ...
3 votes
2 answers
171 views

Is there a consensus as to what is meant by 'Nakamoto Consensus'?

I sometimes hear that bitcoin's key innovation was the Nakamoto Consensus, which solves the double-spend problem without the need for trusted third-party intermediaries. I take Nakamoto Consensus to ...
2 votes
1 answer
154 views

What is the nBits field in the CBlockHeader class?

In the source code for the CBlockHeader class, there is a field called nBits. /** Nodes collect new transactions into a block, hash them into a hash tree, * and scan through nonce values to make the ...
163 votes
6 answers
290k views

What are bitcoin miners really solving?

As with mining, what are the bitcoin miners really solving? I read they are solving hashes, but what does that really mean. Can we see what they are solving? Can someone give an example of what a ...
4 votes
3 answers
167 views

What would happen if miners refused halving

In may 2020 the supply of bitcoin per block is supposed to be reduced by half https://www.bitcoinblockhalf.com/ What if after this phase the first miner or more than 51% of them decide to keep the ...
0 votes
1 answer
60 views

Trusting only the proof of work to receive payments

I understand that a pruned node needs to download all the blockchain in order to verify the blocks and construct the UTXO set. But wouldn't be possible to download the headers only? Let's say if the ...
2 votes
1 answer
214 views

What does `log2_work` in Bitcoin Core's output mean?

I have a question. Does the "log2_work" finally is a "proof de work" ? :) Do you know what does it mean ?
0 votes
1 answer
68 views

Is it easier to reverse the entire blockchain than to guess a private key?

If I am not mistaken you could in theory revert the entire blockchain, by producing nonces which probabilistically speaking required more work. So the (hypothetical) question is: if I wanted to steal ...
2 votes
2 answers
489 views

Is verification of a blockchain computationally cheaper than recreating it?

One of the advantages of cryptocurrencies like Bitcoin that is often repeated is how hard it should be to manipulate past transactions. The reason that is often stated is that you would have to re-...
2 votes
1 answer
105 views

What's the logic behind the way block proofs (in GetBlockProof) is calculated?

Bitcoin Core uses GetBlockProof() function to determine the contribution of a block to the total difficulty of the current chain, aka, nChainWork in CBlockIndex. I'm having trouble understanding the ...
1 vote
4 answers
110 views

Why does an attacker need 51% mining power to overtake the blockchain?

I am really struggling to understand this thing about the 51% attack. Usually whoever mines a block first wins. My understanding is that mining is like a race. In a race, an athlete does not need to ...
1 vote
1 answer
117 views

Proof of work: comparing computed hash with target hash

According to the source code here is where the hash computed by a miner is compared with the target hash: bool CheckProofOfWork(uint256 hash, unsigned int nBits, const Consensus::Params& params) { ...
2 votes
3 answers
76 views

Relation between PoW and integrity?

I'm pretty new to the Blockchain technology. In a video that I watched, the lecturer talked about Consensus Algorithms and said that they're used for maintaining the integrity of the blockchain.  Then ...
2 votes
1 answer
164 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 ...
0 votes
0 answers
27 views

Estimate hashrate from block info [duplicate]

Hi for POW is it possible to estimate hashrate for that block using only available info from getblock rpc ( difficulty , timestamp, etc ) ? Is there a correlation between difficulty and block found ...
0 votes
0 answers
63 views

Why is randomness needed in Proof-of-Work?

In Proof-of-Work (PoW) mining, a miner that contributes 10% of the network hash rate will on average receive 10% of the mining rewards. "On average" means that 10% of blocks are mined by ...
0 votes
1 answer
85 views

Would a consensus algorithm like the one I describe work?

Given n nodes(miners/validators), Every unspent transaction output is broadcasted to all n nodes. Each node will select a batch of transactions and add it to their block. The specific mechanism of ...
2 votes
1 answer
491 views

Chain with most proof of work - hash target or block header hash?

What is calculated towards the sum of PoW of the chain? Is it the target difficulty that has been met or is it the actual block header hash? Say the target is 000000ABC00000000... and I mine block ...
0 votes
3 answers
827 views

Finding Hash with 11 leading zeroes

For an exercise, I'm trying to find a sha256 hash with 11 leading zeroes. For this reason, I wrote a Python script that basically tries all intergers from 1 to N and brute forces the hash. Now my N is ...
0 votes
2 answers
65 views

alternative definition of Proof of Work

If the goal of PoW is only to have a single truth verifiable by all to which to converge. Is it correct to say that PoW is only a method that serves to make it very unlikely that many solutions ...
0 votes
1 answer
45 views

is possibile to fork the bitcoin blockchain and change it checking if the pow is created from a clean energy?

is possible to Clone the Bitcoin blockchain and in the calculation, it does for the difficulty, instead of the global hash power given by the ASICs, put it the global production of clean energy ...
2 votes
2 answers
466 views

Do Full Nodes perform Proof of Work to validate a Block?

I do understand that Full Nodes validate all transactions twice based upon the public key of the users. Firstly, once a transaction is unconfirmed and secondly the transactions that have been mined in ...
1 vote
2 answers
228 views

Where does this 2^32 come from?

Several months ago I was doing research into calculating mining revenue for several crypto currencies. When trying to calculate BTC revenue I found this value 1/2^32 which was described somewhere ...
0 votes
1 answer
61 views

Is it correct to refer to hashes found through proof of work as "proof of work numbers"?

I've seen come commentators refer to 'proof of work numbers'. I suppose these are the hashes found through proof of work, but not entirely sure. EDIT** Regarding where I got the 'proof of work numbers'...
2 votes
1 answer
120 views

Probability of mining maximum of 3 block in next 20 minute

I know that block interval in bitcoin blockchain is exponential distribution. Now I want to know what is the probability that maximum of 3 block will be mined in the next 20 minute?
0 votes
1 answer
55 views

What stage of the bitcoin protocol deals (or 'solves') the double-spend problem?

I understand that a key innovation in bitcoin is that it solves a key problem faced by previous attempts at a digital currency: the double-spend problem. In addition, I also understand that the ...
1 vote
1 answer
130 views

Proof that blockchain converges to the longest chain [duplicate]

Is there a mathematical proof that shows that blockchain converges to the longest chain? It seems not obvious to me how a scattered group of nodes and transaction signals will eventually converge to a ...
0 votes
1 answer
47 views

Is it correct to differentiate between a validated bitcoin transaction and a confirmed bitcoin transaction?

From my understanding, a transaction is first 'validated' by nodes once a transaction is propagated - so in the early stages. These validated, but unconfirmed, transactions are then collected by ...
0 votes
0 answers
16 views

Mining against candidate block hash or previous block hash? [duplicate]

When mining...; a) Is the block header hash of the candidate block used b) OR the block header hash of the previous block + noonce used? If it is a), which I presume, is it then correct that the ...
4 votes
4 answers
1k views

Why is Bitcoin not moving to an ASIC-resistant Proof of Work algorithm?

Bitcoin uses a Proof of Work algorithm that makes it the perfect victim of ASIC mining. As a result, hash power is not very decentralized (more than 50% of Bitcoin's hash power is concentrated in ...
4 votes
3 answers
285 views

Can you get the longest chain by keeping a constant low difficulty?

I'm struggling with this question that should be easy to answer. If the truth is the longest chain, what if I redo all the work from Block 1 until I have the longest chain by keeping a constant low ...
1 vote
1 answer
89 views

How does PoW ensure that all the transactions are recorded and that all the transactions are valid?

I just started to study blockchain and bitcoin yesterday and came up with some questions. If miners can select transactions when creating a block, how is it ensured that all the transactions over ...
1 vote
1 answer
121 views

Can a proof of work chain have finality?

My understanding is that finality is just a rule in the consensus which says any block that gets buried X block deep will be considered unchangeable by the consensus. This has nothing to do with proof ...
0 votes
2 answers
140 views

Why is PoW even necessary?

So I understand the concept behind PoW (that if someone wants to overturn the current chain, they'd have to do all that work again). But why is it even necessary since transactions are confirmed only ...
0 votes
1 answer
316 views

Determination of Block Size Limit

In Bitcoin Mining, there is a limit on the size of any block added to the chain. What happens if, for instance, a block's nonce is so large that the block's size exceeds the limit? Secondary questions:...
0 votes
1 answer
86 views

When should proof-of-work be done? Does it involve in mining a coin? Can it be done without real transactions to be recorded?

I am trying to understand about what bitcoin is. I conceptualize bitcoin as a proof of work required when a new block (or new coin) is created. I also understand that a proof of work involves finding ...

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