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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176
votes
8answers
106k 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.
136
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4answers
226k 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 ...
96
votes
12answers
9k views

Is there a way to set up proof-of-work systems so they would be even more useful?

One of the arguments made against Bitcoin's design choices is that it wastes resources authenticating transactions. In particular, finding small hashes is completely useless for the world. Are there ...
28
votes
2answers
38k views

How does proof-of-stake “mining” work?

I know and understand the concept of proof-of-stake. Instead of requiring users to do a certain amount of power-intensive hashing "work", it requires you to own a certain stake of the currency in ...
28
votes
1answer
11k views

What is proof-of-stake?

As we know one of the important mechanisms of Bitcoin is proof-of-work. How does the concept of proof-of-stake work? How does it differ from proof-of-work?
25
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4answers
71k views

The bitcoin mining algorithm from a programmer's viewpoint

This page: Blocks said mining is actually to solve a mathematical problem, but reading Block hashing algorithm doesn't give much help. I also tried reading bitcoind source code, but reading code takes ...
22
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2answers
5k views

What are the pros and cons of Ripple's consensus as compared with Bitcoin's proof-of-work?

One of the major differences between Bitcoin and Ripple is how they process transactions. I can think of three ways in which Ripple's "consensus" scheme is superior to Bitcoin's proof-of-work: Less ...
18
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2answers
11k 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?
17
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3answers
4k views

Are there alternatives for proof of work?

Bitcoin uses proof of work to secure the network, Ripple uses a global consensus system and PPCoin uses proof of stake. Are there any known alternatives to the above methods?
15
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6answers
5k views

Why do we need Proof of Work in bitcoin?

I know that proof of work shows that the person has put in some time and power into the processing. I also know that bitcoin mining is adding a transaction into the blockchain and then the miner will ...
13
votes
4answers
7k views

Why can't we design a bitcoin that does useful work? [duplicate]

The bitcoin network, including every miner, is the biggest computing project that humanity has created. Thus I ask: why, instead of using it to generate useless data, don't we use it to generate ...
13
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2answers
3k views

What is Proof of Burn?

Can someone explain me: What is Proof of Burn What is the difference between Proof of Burn and Proof of Work How Proof of burn works Which virtual currency uses Proof of burn technology instead of ...
12
votes
2answers
916 views

How can we be sure that a new block will be found?

How do we know the HASH function will produce an output that fulfills the difficulty, i.e. is below 0000...xxxx...xxx? Is it possible that no proof will be found so that the HASH will produce that ...
12
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2answers
724 views

Is it possible for the network to stop finding valid blocks?

The hashing problem is by design computationally hard, because SHA-256 hashes are for all intents and purposes random strings with no direct link to their inputs, and there's no (known) way to ...
11
votes
2answers
2k views

Bitcoin without mining

Several months ago I've stumbled an interesting question about the Ripple system: How does Ripple solve the double-spend problem? Specifically about how double-spending is solved in Ripple. As you ...
10
votes
5answers
6k views

What features of scrypt() make Tenebrix GPU-resistant?

There's a fork of Bitcoin called Tenebrix that is claiming to be CPU-friendly and GPU-resistant (with regard to mining). They say that this is because they're using scrypt instead of SHA256. From what ...
10
votes
2answers
3k views

Will the proof-of-work system end when all bitcoins have been mined?

This article from ArsTechnica is claiming that Bitcoin is not such an environmental disaster, and one of the reasons they mention is that mining will come to an end. Ok, fair enough, there is an end ...
10
votes
4answers
853 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 ...
10
votes
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-...
9
votes
4answers
2k views

How does proof of work inspire trust when the work is just guessing?

I'm struggling to understand the value added by machines guessing at inputs to create a hash below a target value in order to produce a proof of work. I understand the proof of work is somehow ...
9
votes
3answers
6k views

How does Proof of Burn work?

I have been trying to make a comparison between PoW, PoS and Proof of Burn. While I understood the other two, I want to know how exactly Proof of Burn helps in attaining the consensus. One burns ...
9
votes
4answers
353 views

How cooperative or competitive is the mining process?

As each miner works out which nonces it has tried, does it notify the network so that energy isn't wasted on re-processing the same thing by each node? Or is it totally competitive with everyone for ...
8
votes
1answer
1k views

What prevents similar time-warp attacks in Bitcoin as happened to Verge?

Right now (may 2018), Verge (an altcoin with proof of work) was attacked by time-warp attack. More can be read here https://blog.theabacus.io/the-verge-hack-explained-7942f63a3017 What exactly ...
7
votes
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 ...
7
votes
3answers
380 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 ...
7
votes
2answers
572 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
votes
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, ...
6
votes
2answers
357 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 ...
6
votes
2answers
2k views

What happens to extinct blockchains, and transactions inside of them?

While understanding the concept of block chain and proof of work, few things are confusing me. Miners always consider the longest chain(by difficulty) and work on expanding it. Now, lets say two ...
6
votes
1answer
373 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 ...
5
votes
2answers
10k views

Bitcoin alternative designed for NVIDIA

Currently the best graphics cards to mine Bitcoins are all AMDs. What should be changed in the Bitcoin protocol to make the alternative version of Bitcoins better mined by NVIDIA graphics cards? Could ...
5
votes
2answers
3k 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? ...
5
votes
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 ...
5
votes
1answer
570 views

How does scrypt pow work?

Bitcoin's pow is sha256, the hash of header is taken and check against a given target to see whether it is smaller than the target, this can be easy seen as block hash starts with zeros. But how does ...
5
votes
3answers
560 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 ...
5
votes
5answers
151 views

How to protect the early stages of a proof-of-work application?

For a given cryptocurrency or other blockchain application, proof-of-work provides intrinsic security in the algorithm itself that makes it unlikely that someone can attack the network unless they ...
5
votes
2answers
4k views

What is the difference in hashing algorithm between bitcoin and litecoin?

I am having trouble finding litecoin mining specifications. I would first of all require something like this: https://en.bitcoin.it/wiki/Block_hashing_algorithm Except for litecoins. I need to know ...
4
votes
3answers
1k views

What is the problem that mining solves?

Of course, the function of mining is to secure the blockchain, but I'm looking for a more abstract summary of what the exact problem is that mining tries to solve? I believe its called the Byzantine ...
4
votes
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 ...
4
votes
1answer
418 views

Is Bitcoin PoW actually SHA256 + Merkle generation? Or have I misunderstood coinbase/append?

Miners can mutate nonce (32 bits) + time (mutates once a second). This allows for 232 (~4 billion) hashes per second. That's not enough anymore for our ASICs as they perform in the TH/s now rather ...
4
votes
2answers
1k views

Intrinsically useful proof-of-work using Mersenne or Fermat numbers factorization. Could it be possible? [closed]

I was reading this question and got myself thinking - why can't a crypto-currency use as proof-of-work a difficult problem that has value outside of the network? I understand the effort to produce all ...
4
votes
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 ...
4
votes
2answers
291 views

What is the variable in a block that holds hash of found PoW?

Can anyone please tell me, which variable holds the hash of the solution of block's PoW in broadcasted block? I know that a block consists of (I am pretty sure I am forgetting some variables here): ...
4
votes
2answers
558 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 ...
4
votes
1answer
190 views

In what sense does the security model of proof-of-stake require users to “log on to the internet every few months”

This is primarily a question about something I heard Vitalik Buterin say in an interview the other day. (Unchained podcast's January 9, 2018 episode, at 34 minutes, 15 seconds) I quote: As far as ...
4
votes
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 ...
4
votes
2answers
748 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 ...
4
votes
1answer
503 views

What is proofOfWorkLimit?

Look at the code below from android bitcoin wallet: proofOfWorkLimit = Utils.decodeCompactBits(0x1d00ffffL); And look at the code from bitcoin qt wallet: static CBigNum bnProofOfWorkLimit(~uint256(...
4
votes
1answer
4k views

Work rejected. Server says: Stale or alien proof of work

I get this error using BitMinter Client v1.3.2: Work rejected. Server says: Stale or alien proof of work about every 15 - 45 minutes, just mining on my GPU. What is happening? What does it mean to ...
4
votes
2answers
813 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 ...