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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853 views

Implementing NiPoPoW algorithm

Hello, We, a small team, have implemented about 95% of a breakthrough scientific proposal that is describing the NiPoPoW Non-Interactive Proofs of Proof-of-Work. You can find our source code ...
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1answer
44 views

As a miner, why would I forward transaction with high transaction fees to other miners?

Miners receive transaction and broadcast it to other nodes. Node that solves the puzzle will add that transaction into the block it mined. But as a miner why would I broadcast a transaction with very ...
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1answer
175 views

Can Bitcoin(PoW) work under partial synchrony?

This paper rigorously proves that Bitcoin can achieve consensus under the assumption of bounded message delivery time: Messages in a mailbox may be delivered in any order, and at any ...
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1answer
33 views

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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1answer
105 views

What dead simple algoritm can be used for generating checksums by pen and pencil?

I'm holding a course on Bitcoin and blockchain technology. On my agenda I have an exercise where I'm going to let the attendees create their own blockchain on the wall using post-its. I'm in search ...
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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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1answer
103 views

POW based blockchains systems Majority Attack

TL;DR: With only 30% of network power a Majority Attack is possible and profitable. Am I missing anything? Generally speaking, blockchains based on Proof-of-Work authentications are using amount of ...
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2answers
82 views

group proof of work

Right now, every node in a Proof of Work system, solves the POW puzzle independently. Is there any concept of group proof of work, where everyone in the group needs to solve part of the puzzle.
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2answers
1k views

51% attack and rewriting to the latest checkpoint

This is not a question about the consequence of a 51% on the price nor as to the motivation of the attacker. Let say we don't care that it's not realistic and we don't care that the attacker wouldn't ...
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1answer
196 views

How finding a working nonce says anyting about the validity of an initial transaction

I am by no means an expert, nor a cryptographer, but I would be interested in knowning a little bit more than what happens at the end of the following chain of events. What happens at the end of the ...
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4answers
114 views

Use of proof of work in bitcoin

I am trying to understand what problem in bitcoin proof of work solves and came to this somewhat helpful quote: So, for instance, if a miner controls one percent of the computing power being used ...
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2answers
357 views

What's so special about six blocks for confirming transactions?

I read that when your transaction is part of a block that has five other blocks on top of it, you can feel safe that your transaction is not in danger of being orphaned because someone else would come ...
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1answer
754 views

How does the bitcoin transaction fee get paid to miner(s)?

According to https://bitcoinfees.info/ The current "cheap" rate for a bitcoin transaction is $22. How does this get paid to the miners? Is it just one miner that verifies the transaction, puts it ...
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3answers
71 views

What are the chances that Bitcoin changes its proof-concept one day?

Is it realistic/possible that the bitcoin core team make a new Bitcoin Improvement Proposal (BIP) on day in which they propose to change Proof of Work (POW) with something else (proof of stake for ...
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1answer
144 views

Blockchain beyond bitcoin etc. - Who is mining?

People are praising the blockchain for use in all kinds of environments where a secure transaction history is required, e.g. logistics etc. My question: Let's say someone sets up a blockchain for ...
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2answers
283 views

Why don't the miners just take profit from our coins and make the coin worthless?

You own a very valuable thing and you want to go to holiday without it, but there is nobody who you trust and who can look after the thing. So you take somebody unknown to guard it. You pay him a fee ...
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1answer
285 views

A theoretical low cost attack scenario in PoW currencies

The scenario was designed by user:croraf and me in discussing a question of mine yesterday. To make it more clear, I want to present it here again in a stricter design. To do it in a clear way, first ...
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3answers
359 views

Egoistic miners combined with large transactions destroy PoW?

EDIT There is a clearer description of some parts of the problem in the link questions. If there is a transaction value much higher than the payment for mining 10 new blocks, how can you trust this ...
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1answer
647 views

Where can i find proof of work in bitcoin core source code?

does anyone knows which part of the bitcoin core source code contains the proof of work for mining, creating of block and adding to blockchain? what are the files and functions involves? https://...
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1answer
205 views

Who decides what the next, correct Nonce is?

As I understand finding the correct Nonce is the basis when hashing transactions for Proof of Work. How and where is this decided in the ecosystem what the next Nonce is? In my limited understanding ...
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2answers
148 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
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2answers
82 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 ...
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2answers
597 views

How does a miner get selected in Proof Of Stake?

I am trying to understand POS. I get that POS uses currency held analogous to the hash power held in POW system. More the stake we have, more are our chances of mining the block. At various sources I ...
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1answer
65 views

Bitcoin Proof of work puzzle inconsistency

At this time, I am really confused about the Proof of work puzzle because as I have seen in some documents, there are 2 different ways to talk about them. The first one I have seen is from some ...
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3answers
379 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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2answers
114 views

How does the network know the legitimate chain in a double-spend attempt?

Apologies if this has been covered, but there's one area of the Bitcoin network that is not clear in my head, and it's intimately linked to the double-spend problem. Suppose Person A is purchasing an ...
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1answer
136 views

How is mining time validated?

New target is calculated from the T(new_block-1) - T(new_block-2016). Here T is the time miner mined the block. Miner itself sets this time for the block. Thus miner can falsify this time. I see a ...
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3answers
4k views

How proof of work prevents double spend

One article I am reading said that proof of work system is used in Bitcoin to prevent double spending. More particularly: Imagine we are protecting against double spending in following way. When Bob ...
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2answers
4k views

altcoin debug.log shows ERROR: CTxDB::LoadBlockIndex() : Failed stake modifier checkpoint height=0

What I have done so far: Generated new Genesis Block Generated new MerkleRoot Updated MerkleRoot Updated Genesis block values Commented out these lines Compiled on CentOS 6 Created altcoin....
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1answer
163 views

Creating blocks while more transactions arrive and proof of work mechanics

I am having a hard time understanding the details of how blocks are getting created by miners while many transactions are being received by various nodes at slightly different times and what ...
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1answer
52 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 ...
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2answers
747 views

How many nonces on average do I need to try in order to get n leading zeros?

Assuming 256-bit hash output, how does the (average) number of nonces I need to try (to solve the proof-of-work puzzle) grow with the number of leading zeroes required, n? Is there a bound on this ...
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1answer
200 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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1answer
89 views

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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1answer
741 views

Steal proof-of-work answer from a miner [duplicate]

Is it possible to steal proof-of-work answer from a miner who has insecure machine? Consider a miner who has insecure machine found correct answer of proof-of-work and an adversary steals this it and ...
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1answer
289 views

What is the downside of not using Proof of Work for validator selection?

Bitcoin uses Proof of Work for two things: one is to secure the blockchain with strong cryptographic signatures like a Merkle tree, and the other is to crown the validator which "mines" a solution as ...
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1answer
395 views

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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2answers
2k views

Transaction verification vs block mining

I cannot clearly understand if the transaction verification is done over a single or double phase. This is my understanding. Once a transaction is completely assembled, its inputs and outputs ...
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5answers
171 views

Application of proof of work in bitcoin

Proof of work in spam I understand very well how proof of work is used to prevent email spam for example. Reasoning is since computing the right hash (e.g. with predefined number of zeros for example)...
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1answer
105 views

Are transactions verified before miner solves the block?

In the PoW mining equation... Hash = (Nonce x prev_hash x list of transactions) the miners find the nonce to add the block to the blockchain and receive the block reward. As we can see, the hash is ...
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1answer
391 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 ...
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2answers
157 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
3k views

How much “Proof of work accepted by server” needed to generate 1 bitcoin (or a part of it) [duplicate]

I am using Bitminter client, and I am confusing about how much I earn in one week while my system working overnight. https://bitminter.com/ says "Mining one bitcoin with just a PC now takes millions ...
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1answer
176 views

How the first succesful miner is ensured his reward

With my still rather limited knowledge of bitcoin, I was wondering how the correct origin of proof of work is ensured. Specifically, when a miner successful computes a valid hash and is to broadcast ...
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7answers
352 views

Justification of usage of Blockchain by banks

After learning a bit about Bitcoin and Blockchain Technology, I do not understand how any bank is going to use it. My understanding is that the blockchain is useful in an environment of mistrust. In ...
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1answer
116 views

Are the mining incentives of bitcoin compatible with the existence of a competing Proof-of-Work chain? [closed]

Scenario A: A chain split occurs due to a bug or contentious rule change (i.e. the miner incentives aren't changed in any way). Both coins initially start out with the same difficulty (and won't ...
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1answer
9k views

What happens when there are no Bitcoins miners anymore [duplicate]

So if I'm not wrong, the proof of work is the way to validate all the transactions in a Block. The miner gets (at the moment) 12,5 Bitcoins as a reward for each validated block. So my question is: ...
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0answers
319 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, ...
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0answers
41 views

What's a good repo to fork if you want to create a blockchain like a “Math” coin or Curecoin. (mining equations, not hashes)

I want to create my own crypto currency and I want to know what's the best github repo to fork when it comes to making a blockchain that's based off of getting the miners to do mathematical ...
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0answers
115 views

Zero-knowledge/Arthur-Merlin Proof-of-Work for NP-like problems with coin flips hashes of recent transactions [closed]

On a previous answer to a question about making proof-of-work more useful, two challenges were provided: "1. The work must be much, much easier to verify than to do, and 2. The work must in fact ...