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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277 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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2answers
609 views

Could an algorithm be made ASIC-resistant by simply adding deterministic permutations depending on the hash of the previous block and the nonce?

I was thinking of permuting bits in a block before it is hashed, in order to require some adaptability from the mining hardware while retaining the security of SHA-256. Permutations would depend on ...
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1answer
3k views

Can Artificial Intelligence be used to mine BitCoins faster?

Can Artificial Intelligence be used to find more efficient mining algorithms? Is there only one algorithm that can be used to mine? EDIT: Asking about running the SHA(SHA(block header)) more ...
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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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3answers
353 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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329 views

What is the difference between PoW and PoS regarding computations when determining a new block?

According to Buterin there are 600 trillion computations done per second using SHA256. He and other sources say that PoS solves the issue of not requiring so many computations but I do not completely ...
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2answers
225 views

Is it possible to build mining reward pooling directly into Bitcoin?

Mining pools were formed quite early in Bitcoin's history. Since then, they have not been considered ideal because of more and more centralization creeping in. But it seemed the community has learned ...
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4answers
5k views

If SHA256 produces an alphanumeric hash, how can a hash be “less than a certain value”?

I was under the impression that Bitcoin's method for validating a hash involved making sure the hash started with a pre-determined number of zeroes. However, after reading the docs here, I see the ...
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298 views

Is there a PoW system that shows cumulative work without an ever-increasing proof size?

Let's say I have an output in the blockchain at height 100,000. At height 200,000, I want to prove that my output has the work of 100k blocks built onto it, securing it. In Bitcoin, proving that the ...
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7answers
343 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
829 views

Why change the nonce instead of just rehashing?

Why do miners increase the nonce to compute a block hash rather than just generating a random block hash? It seems to me that both approaches would have the same likeliness of finding a result that ...
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3k views

How transactions get added to a ledger?

I just can't seem to understand how bitcoin works. Here is what I understand so far. Alice sends 1 Bitcoin to bob's public address A new transaction gets created for miners to approve. A transaction ...
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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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379 views

Why you need to rehash each block after a changed block when changing data in a blockchain?

Maybe my question is stupid, but, why you need to rehash each block after a changed block when changing data in a blockchain? Each block contains a hash of its data and hash of previous block. If I ...
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829 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
120 views

Would miners have an advantage by proceeding randomly?

If most miners are looking for solving their proof of work in a prescribed order (perhaps preceded by a prescribed way to break down the search space, e.g. by dichotomy); is there not an advantage for ...
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1answer
208 views

In Proof-of-Stake, can a block creator fudge the block hash?

In Proof-of-Work, a block hash is costly to manipulate (say, wanting the hash to be even, or have the hash of the hash smaller than some number) since there is a lot of computing power put into ...
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1answer
207 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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1answer
421 views

ASIC resistant PoW mechanism that generates new hash functions. How does that work?

From Vitalik Buterin's post regarding "On Mining", he mentions: The second approach is somewhat different: create a mechanism for generating new hash functions, and make the space of functions ...
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1answer
64 views

Proof of work - does the equipment matter?

It technically doesn’t matter whether I am using a super computer or a laptop to do the proof of work, it’s simply that with a super computer I can go through the attempts much faster, which means I ...
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81 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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206 views

Why do some mining algorithms run “cooler” than others?

So, there are some altcoin mining algorithms now that run cool, such as X11 and groestl. By cool, I mean even when mining at full GPU capacity, the card still remains at 60C or cooler with little to ...
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359 views

Do multi-PoW currencies open up additional attack vectors on a blockchain?

I'm curious if there have been any technical evaluations of the vulnerabilities of cryptocurrencies that utilize more than one proof of work algorithm - for instance, myriadcoin or huntercoin. ...
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461 views

Proof of work - lottery approach

I'm sure I am missing something here. But not sure what ... Proof of work - after all is said and done, when a hash is found (about 10 min), it is said to be like someone hitting the lottery. Anyone ...
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1answer
138 views

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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672 views

Why was finding a hash beginning with a certain number of zeroes chosen as the proof of work?

It seems to me that the reason the proof-of-work involves finding a hash beginning with a (temporarily) fixed number of zeroes is because one can easily check whether they have solved the problem by ...
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2answers
1k views

How can a block be considered more difficult to solve/hash than another one?

In this answer: https://bitcoin.stackexchange.com/a/760/28219 It is said: Because of all this work, when a Bitcoin client signs on to the network it can trust the block chain that was most ...
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1answer
125 views

Why do we need to chain the blocks (creating blockchain) in a permissioned blockchain?

The main question is: What does "chaining block" mean in a permissioned blockchain? OR in any blockchain network in which creating a new block does NOT need consuming resources/energy ? (even in the ...
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1answer
164 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
30 views

When does miner insert the coinbase transaction?

When a miner creates the candidate block with transactions from the mempool, does he insert the coinbase transaction after winning the PoW or during PoW?
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1answer
423 views

Challenge difficulty adjustments

Basically for this question I need a confirmation that all of my listed assumptions are fairly accurate. The bitcoin network measures how much time it took to create the last 2016 blocks in a ...
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2answers
32 views

How do bitcoin miners determine the next valid state of a ledger?

I know bitcoin miners compete for a reward by seeing who can solve a difficult hashing problem first (proof-of-work). However, how does this random hash problem help validate the transactions in the ...
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1answer
59 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
86 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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1answer
248 views

Can the mining pool with the most mining power always win? [duplicate]

Suppose we have three mining pools, one with 40% of computing power, and the other two having 30% of computing power each. Will the node with 40% power, be able to solve the puzzle for each node ...
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2answers
334 views

What happens to a miner's work when they restart?

I am studying the bitcoin internals and especially the proof-of-work. The proof-of-work is based on the mathematical problem that we have to compute from an input that produces a hash with a certain ...
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1answer
47 views

How do blockchains in each nodes maintain consistency?

What I understand as (Please correct me if any statement is wrong) Every full node tries to generate a new block, in which different amount of transactions are included and what to be included will ...
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2answers
322 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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3answers
3k 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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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: ...
2
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1answer
66 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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2answers
153 views

Can a Blockchain be Built Like This?

Can a Blockchain be Built Like This? 1) Alice sends Bob one X-coin. 2) The blockchain's protocol takes X and the next (say) 100 transactions and puts them in a block. 3) Distributed peer-to-peer ...
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1answer
146 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
424 views

why verification of transaction after proof of work?

I have question about bitcoin protocol. In Satoshi's paper it is mentioned that: New transactions are broadcast to all nodes. Each node collects new transactions into a block. Each node works on ...
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1answer
563 views

What sort of calculations do the miners have your computer do? [duplicate]

I recently heard of a new cryptocurrency (or maybe it's not new and I'm just out of the loop) called Gridcoin which uses your GPU/CPU/ASIC to do research calculations rather than "meaningless" ...
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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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1answer
114 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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0answers
302 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
113 views

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

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 ...
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1answer
357 views

Where is the spec of HashCash so that I can implement it in Java from scratch?

I would like to implement HashCash in an efficient/fast/garbage-free way. Is there a spec to do so? How can someone go by implementing HashCash from scratch?