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# 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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### 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 ...
31 views

### 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 ...
63 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 ...
45 views

### 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 ...
22 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 ...
28 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 ...
78 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 ...
61 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. ...
77 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 ...
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?
54 views

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

How do offchain transactions get validated whilst using Lightning network?
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 ...
521 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: ...
139 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 ...
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?
143 views

### 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
80 views

### 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 ...
51 views

### 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 ...
194 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 ...
155 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, ...
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 ...
145 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?
227 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"=>"...
41 views

### Finding target based on difficulty calculation

I'm trying to find the current target value, but it is not listed in any place. So far I found out that the only way to get target value is to calculate it from "difficulty" value, which is now: 6,379,...
32 views

### Estimating difficulty of “Memory-Hard Proof-of-Work” based on “size of memory”?

In Bitcoin proof-of-work, the difficulty of Proof-of-Work is estimated and calculated based on total hashing power of the participants. If total hashing power of the participants is higher, then PoW ...
37 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 ...
186 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
107 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 ...
58 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 (...
343 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. ...
182 views

### Is the purpose of proof-of-work the immutability of the blockchain?

I have a disagreement with a person: I believe that the primary and most important goal of including proof-of-work (and therefore the nonce) in a block is to make it hard for an attacker to change ...
315 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 ...
42 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 ...
193 views

### Has anyone verified what your CPU is being used to do when it “mines” for bitcoins? [duplicate]

I understand that "mining" for bitcoins requires your computer to do work that you don't monitor, so my question is, how do you know what it is that your computer is doing? Has anyone verified what ...
110 views

### How are miners prevented from doing too much work?

I understand that scripts can be written within transactions that make the miners do some work. How does Bitcoin ensure that scripts that make miners do too much work are prevented?