Questions tagged [proof-of-work]

A proof-of-work (POW) system is an economic measure to deter denial of service attacks and other service abuses such as spam on a network by requiring some work from the service requester, usually meaning processing time by a computer.

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Even if I own 51% of stake (or have 51% computational power) and try to cheat, can't others still see that my block is invalid?

I'm thinking about how proof of stake works exactly. As I understand, here is how it is secure: I cannot forge a tx where random A pays me X amount because I would need the private keys of A. ...
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Ethereum2.0 Shard chains will be PoW or PoS

I'm sorry if this is a basic question. But will the new shard chains for Ethereum2.0 be PoW or PoS? I know the plan is for Eth1 mainnet to "dock" onto the beacon chain eventually and be its ...
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Why don't blockchains use simple voting based consensus algorithms?

Suppose we have an malicious agent Bob with account balance of 100 units trying to double spend a coin by broadcasting two messages simultaneously: A: Bob sends Alice 100 units B: Bob sends Emily 100 ...
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Leverage short positions in decentralised PoW currencies

Hint I asked this question in a similar style already on bitcointalk and on bitcoin.stackexchange. But in these threads, there are no good answers and I thought maybe it would be better to ask the ...
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How are difficulty of finding a proof of work dynamically regulated without a central body? [duplicate]

The probability of a miners to mine a block dynamically changes so that blocks are mined at regular intervals.How does block chains accomplish this without a central regulating body,
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“Universal Proof of Work” with SNARKs?

If SNARKs are able to prove computations of arbitrary complexity and difficulty were executed correctly, would it be possible to use them to create a Proof of Work system where ANY computation can be ...
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Ethereum POA attack scenario

I am studying consensus algorithm. In the case of the proof-of-work algorithm, a double spending attack was possible by the miner making a transaction and presenting the longest block from which the ...
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Ethereum vs bitcoin technology [closed]

I have understood how bitcoin works (coinbase block, mining, links between transactions, hashrate, nounce, proof of work, ...) Now i want to understand how Ethereum works. Can we say it is the same ...
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When an Ethereum transaction event occurs, is there a case when it was not included in the main chain later due to a fork?

I know Ethereum is a POW blockchain where forks take place. The transaction event is issued after executing the transaction on the node. If a fork occurs, is there a possibility that the transaction ...
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Ethereum private network behaviour

I tried launching a private POW etherium blockchain. Following is what I observed. Attempt 1 2 node network. Node1 is a miner, node2 doesnt not sync Attempt 2 2 nodes network. Node1 is a miner, send ...
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Does successful mining require the block's transactions in advance?

Typically a miner decides which transactions go inside a block. But does this have to be so? Is the actual mining process just a process to find the right nonce regardless of block contents or does it ...
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What if difficulty exceeds the length of a fixed sha256 hash in proof of work?

Hello im a newbie in Blockchain, i got to know some basics, but im confused that what if the difficulty exceeds the length of a sha256 fixed length string example : The fixed length is here 64 (sha256)...
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Is Ethereum 2.0 (Sharding Ethereum) only PoS based? Or a combination of PoW + PoS?

Does Ethereum 2.0 (Sharded Ethereum) only use PoS (Proof-of-stake) for consensus mechanism ? Or Does it use a combination of PoW + PoS ?
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Why does proof of work targeted zeros always comes at the start of hash? why is it not in the middle or the end of hash?

My question is why always targeted zeros come at the start of hash of the block? I have never seen more than 2 zeros in middle or somewhere else in the hash of mined block... What's the reason?.... ...
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Resources of a miner's reward in Ethereum?

To compensate the miner who could solve the PoW as the first one, they will receive some coins as a reward for keeping them motivated due to the costs related to mining process (electricity and ...
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Deliberate Slashing: Don't slashing and leaking incentivize DDOS attacks on smaller nodes? Won't this centralize POS more than POW, even?

In Ethereum's proposed proof-of-stake algorithm (POS): A traditional node operator can't host a node themselves (e.g. on a home network), someone could just DDOS their node to bring them offline. ...
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how transaction in block-chain is validated

Please explain complete procedure/journey how transaction in block-chain get validated by miners, From broadcast of transaction to become part of new block.
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What should I prepare for the coming ETH 2.0 upgrade as a Dapps developer?

As announced, Ethereum is expected to be its upgraded version Eth2.0 probably from 2020. There will be several upgrades like PoW to PoS/Casper FFG eWasm integration sharding (Casper CBC) These ...
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During the POW/POS transition, why would a POW miner choose to mine on the chain with the POS consensus algorithm?

As the title says, what incentive does a POW miner have to mine on the hybrid POS chain? They would, effectively, be removing their own economic incentive from the consensus mechanism. I understand ...
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PoW in Public blockchain Vs. PoW in Private blockchain

I am reading about consensus mechanisms in blockchain and it is stated that PoW (Proof of Work) requires longer confirmation time compared with voting-based mechanisms. But some things are not clear ...
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Why is PoW needed to confirm transactions and add new blocks [closed]

I have read and I vaguely understand about how Proof of Work works and what does it do. But why PoW? Or more bluntly, why do we need any algorithm at all to add new blocks. What would happen if ...
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What is the total supply of Ether?

In Bitcoin, the total supply is capped at 21 million BTC. Is the total supply of Ether capped? How much will be mined before the Proof of Stake (POS) transition, and how will POS affect the issuance ...
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Why 51% hash power require to control the network?

Why 51% is explicitly mentioned to get control over the network?. Why not 50 or lesser ?. Anyway there is no central authority to decide, whether 51% is attained or not?.
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What do the parameter in sha3() in Proof of Work implementation of Ethereum mean

sha3(nonce, currentChallenge, block.blockhash(block.number-1)) In this line I get it that blockhash is a random number, but why are we taking it from the previous block, any hard and fast rule here ? ...
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When is a new block created?

I am currently reading an interesting book about solidity, and I'm reading about block creation. This gives a good overview: The book mentions that the maximum size of a block is determined by the ...
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How many nodes can confirm the correctness of the hash value by miner?

After mining the hash value for the new block, How many nodes can confirm the correctness of the hash value by miner? In one of blockchain paper, all other nodes must mutually confirm the correctness ...
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Does the ETH blockchain have fundamentally more branching than BTC?

Intuitively speaking, ETH seemed to have simply increased the average block generation rate from one every 10 min in BTC to 1 every 15 seconds. There doesn't seem to be any other protection against ...
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How to make atomic swap between Ethereum and POS chain?

There's simple way to make atomic swap for smart-contact chain and any POW chain. For example for Ether <> BTC: Alice sends some Ether to the swap smart-contact which locks this money. While ...
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How are transactions ordered in POS?

With POW, the miners who finds the block chooses the order of transactions in that block. How will this work with POS?
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How does the network validate a block in PoS

In general PoS, the forgers stake their coins and then a validator chosen in a pseudorandom fashion gets the chance to validate a block. But how do the whole network validate it? In PoW, for example, ...
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How feasible it to combine Proof of Work and Proof of Elapsed time consensus to create a custom blockchain?

I wonder if it feasible to create your own custom consensus by combining Proof of Work and Proof of Elapsed time? How would I approach it? Any tools or frameworks to build it? I appreciate all the ...
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Who generates the mathematical problem for miners?

In POW miners solve an problem for successfully mining a block, who provide the question to the miners ?, does all miners work on same problem ?, and how the miners verify the answer ?, if the problem ...
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Can't we incentivize miners to include more transactions in their block?

If you go to etherscan.io, you can see that each block has the different number of transactions. Can't we incentivize miners(e.g. give more rewards ) to include more transactions in their block so ...
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what does memory hard mean in ETH POW? [duplicate]

I came across the term memory-hard while ready about ETH POW algorithm. What does it mean when someone says that POW is memory hard?
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Transaction throughput: POA vs POW in private blockchain networks

I know that proof of work is resource intensive, while proof of authority is much faster as no consensus is required since the network is validated by the proper authorities. But in terms of the ...
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how to setup hybrid PoW+PoS or PoA private network (geth)

I am aware about PoW and PoA setups of ethereum private networks but would like to know if anyone could help or point me the direction how to build a hybrid PoW + PoS or PoW + PoA ethereum based ...
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How is the Two Generals Problem solved with proof of work?

Here is an email where Satoshi Nakamoto explains how PoW solves the Byzantine Generals' problem http://satoshi.nakamotoinstitute.org/emails/cryptography/11/ The proof-of-work chain is a solution to ...
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Nonce in proof of work

When a block is being mined nonce will be generated so that the nonce is appended with the previous block hash,data. Then the resulting hash of that appended value should be less than the target. The ...
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Is it possible to verify Ethash PoW in a contract?

Reading on EtHash, I was thinking if it is possible to verify the current Ethereum Proof Of Work by a smart contract. There is an instruction SHA3, which computes 256-bit hash, but EtHash uses 512-bit ...
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Is POW required for a private blockchain?

PoW is a mechanism to keep block chain incorruptable from malicious nodes. Now in a private block chain where all nodes are supposed to be honest, what purpose PoW would serve? Would it not be just a ...
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Is “Proof-of-work” a subset of “Byzantine fault tolerance (BFT)”?

Can we say that Proof-of-work is a type of Byzantine fault tolerance (BFT) ? In other words, is PoW a subset of BFT ? Or they are two different categories? Please note that there is a similar ...
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I don't really understand how mining works, anyone can help?

I am currently studying Ethereum all by myself, and am struggling to understand how mining and Proof of work work. I have read many posts and books about it but still hard to understand how the ...
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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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How blocks are calculated in POS

In POS people bet on the blocks to be added to chain and the honest block wins and the people who have voted for honest blocks get a share in the rewards. But one thing i am still confused is, who ...
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Proof of work vs Proof of Stake [duplicate]

I'm newbie to Ethereum and trying to make things clear. I've read few articles about PoW(proof of work) vs PoS(proof of stake) and what I understood is, Proof of Work is nothing but the mining, in ...
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Will a higher stake make more money in PoS?

Since I'm very new to this I'm just going to assume I'm getting it wrong. But here it goes anyway... The higher my stake, the more money I make. This is my raw understanding of how proof of stake ...
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What are the challenges involved moving Ethereum from POW to POS?

I'm aware of the idea to roll out the POS protocol by using a hybrid model of POS/POW. What are the challenges of such a change? This hybrid model would make mixed adoption(for legacy users and new ...
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How many blocks can a cache of 1gb (1024) hold tentitively?

If I use a command geth --cache=1024, how many blocks it will hold runtime in cache. And what will be the size of each block. Is there any calculation? And is there any way using which we can force to ...
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From Proof-of-Stake to Proof-of-work

Have any (cryptocurrency + blockchain)s switched from proof-of-stake to proof-of-work?
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Using Custom PoW Algorithm with Parity?

If I wanted to create a PoW alrorithm to replace ethash on a private blockchain, how would I tell Parity to use it?