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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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1answer
282 views

The 51% assumption

I am new to understanding how bitcoin works but reading up a little on PoS and PoW, I understand that anyone with over 50% of the network resources (bitcoins or computing power respectively) can ...
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1answer
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 ...
4
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1answer
338 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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1answer
159 views

Zero-BTC transaction fees, service-specific mining pools and external compensation

Bitcoin is a network that is proven to be stable, but if you want applications on top of Blockchains you have to play by the rules of the system. For notary use cases (for example), where you would ...
4
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1answer
2k views

How does a time warp attack work?

I more or less understand how an attacker (with less than 50%+1 of the hashing power) can artificially lower the block difficulty by messing with timestamps. I also understand how such an attacker ...
0
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1answer
771 views

What prevents a miner from faking nonce hash

What exactly prevents a miner from presenting a random nonce hash of the block with enough zeroes at the start to get chosen? How is the new hash verified by the other nodes? Since as I understand ...
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1answer
622 views

Bitcoin Mining Computational Power [duplicate]

1/ I do not understand why bitcoin mining is random when hashing is deterministic. reference : https://en.bitcoin.it/wiki/Nonce Can the mining pool with the most mining power always win? What value ...
3
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1answer
368 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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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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1answer
191 views

Why was the chain with the largest work chosen as the metric of consensus?

There seems to be a myriad of ways to find consensus (PoW, PoS, PoD, PoE and various other methods and hybrid approaches). What was the reasoning behind bitcoin being PoW and treating the chain with ...
4
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2answers
227 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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3answers
20k views

What's the difference between PoW and PoS?

I'm looking for an explanation of the difference between Proof of Work algorithm and the Proof of Stake and how they relate to Bitcoin and the Blockchain. Also looking for a fairly simple, non-...
3
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1answer
122 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 ...
3
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1answer
848 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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1answer
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?
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1answer
168 views

Projects built on the Tendermint platform?

The Tendermint project sounds like a very promising proof-of-stake implementation. What public projects are being built on this platform?
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1answer
252 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 ...
2
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1answer
707 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 ...
1
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1answer
467 views

Abrupt increase in difficulty of proof-of-work

I am simulating a private bitcoin network that I started with the initial difficulty set to (1/2)^16, however after about 20 blocks of mining on the network it increased to 1 and has been constant ...
4
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2answers
828 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 ...
3
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1answer
216 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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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
113 views

What are the chances of someone coming up with a new and simple/out-of-the-box solution for the double-spending problem?

The proof-of-work solution is simple but has many drawbacks (waste of time, energy and uncertainties about its security in the future). The consensus solutions proposed by Ripple/Stellar are too ...
2
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1answer
373 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?
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2answers
612 views

What is the hash function used by Bitcoin proof-of-work?

Probably a simple question, but I believe it is important to state it clearly for the beginners like me out there. What is the hash function used for the Bitcoin proof-of-work? What implementations ...
2
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1answer
438 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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1answer
687 views

Why is POW/POS absolutely necessary to run public distributed ledger?

my first question here, so please be patient with me. Thank you in advance. Q: Why exactly are POW/POS mechanisms needed to secure the blockchain (in bitcoin as well as in other alts)? + what is ...
4
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2answers
760 views

How does Peercoin (or other PoS) prevent timestamp forging effecting hash attempts or random minting?

I understand that every second the timestamp & potential transactions is hashed. I guess there exists a "start time" on the block chain we can't roll the clock before because transactions with ...
3
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2answers
320 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 ...
7
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3answers
5k views

What Value does mining provide?

After reading the O'Reilly book and perusing online resources, I'm still confused about the value that the actual mathematical mining provides to Network (I understand it does provide value, but not ...
4
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4answers
1k views

Why can't Bitcoin switch over to Gridcoin's proof of work system?

Gridcoin advertises itself as a "a mandatory competitive reward mechanism based on contributing the most towards BOINC projects on top of existing cryptocurrency technology." Is there a reason why ...
2
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1answer
566 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

Generating blocks in regtest: “hash doesn't match nBits”

I'm getting this error in regtest mode after setgenerate RPC: ERROR: CheckProofOfWork() : hash doesn't match nBits After looking for error text in src I found a match in pow.cpp (obviously ...
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2answers
751 views

What is the most lightweight proof-of-work algorithm?

I know litecoin was created back in the day using Scrypt as to make it more lightweight but also harder to build ASIC hardware from - so everyday computers could mine. Are there other algorithms one ...
7
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3answers
388 views

What other whitepapers are there for coin distribution models like POW (proof of work) and POS (proof of stake)?

I'm looking for other types of distribution models for crypto coins that are like POW (proof of work) and POS (proof of stake). I'm assuming these are a type of distribution model for coins, or is ...
5
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3answers
564 views

Is there a proof of work system which takes significantly more memory to generate than it does to verify?

Litecoin resists GPU speedup by using an scrypt-based hashing function that takes some amount of memory to generate and verify. The problem with this is that the r parameter needs to be set high ...
0
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1answer
228 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"=>"...
6
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3answers
1k views

Does every nonce really have an equal chance of winning?

I set out to test the claim: "Every nonce has an equal chance of winning." Time Evolution So, I plotted, with gnuplot, the nonce values vs. hashes for all the valid blocks in the blockchain:(Also, ...
4
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2answers
1k views

Why does an adversary have to control 50% of the computing power to double spend?

If transactions in a block are valid, in order to add that block in the block chain, a proof of work needs to be found. I have read the bitcoin paper by Satoshi. If the difficulty of the proof of ...
3
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1answer
425 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 ...
10
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4answers
864 views

Is it possible to make PoW ASIC-resistant through dynamically generated hash chains?

Bitcoin's static proof-of-work function SHA256(SHA256(data)) was apparently easy enough to be implement as ASIC which lead to the re-centralization we see today. But what if the PoW function changes ...
7
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2answers
2k views

How is it that concurrent miners do not subvert each other's work?

Every time a new block is added on top of block chain, the miners have to restart their work because the next block has to have a proper reference to previous block. Let's suppose that there is some ...
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2answers
153 views

Are there any stochastically dependent proof of work algorithms?

In bitcoin, the probability of discovering a block on the X-th hash is the same1 as it is on the Y-th hash. As such, the probability of discovery is stochastically independent. Are there proof of ...
6
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1answer
379 views

Is it possible to combine PoW with PoS by taking turns?

I have read about cryptocurrencies and am very excited by many. I have read that one of the worries and constant debates is Proof of Work vs Proof of State with respect to securing the validity of the ...
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2answers
81 views

Theoretical security of mining bitcoins

Is it possible to change rules of mining bitcoin division? rewrite P2P bitcoin client (or write maleware) which will be pretending that fake bitcoin client is legal, original client distribute ...
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1answer
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 ...
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2answers
5k views

Who are you solving algorithms for and why?

I am sick to death of people responding to my question with logistics of "how to" mine data or just that you are solving "mathematical concepts" and "algorithms." What I do understand is this - some "...
7
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2answers
603 views

How does a mix between Proof of Work/Stake work? (Peercoin)

I think I understand Proof of Stake and Proof of Work from a conceptual point now. For themselves both are good ideas for sure, but how would a crypto currency like Peercoin (PPC) combine both of them?...
6
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2answers
359 views

What is the reason for using PoW in bitcoin?

As we know bitcoin uses Proof of Work Concept and it introduces never ending long block chain and some other issues. Why is it not designed in a way to use consensus algorithms what ripple uses? What ...
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3answers
1k views

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 ...