Questions tagged [consensus]

The process used by mutually untrusting users to agree on the validation and execution of transactions and smart contracts.

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19 views

What is the process for actual validation of transactions?

What is the actual process of validating transactions on the blockchain? For example checking that no double spend has occured? I know PoW and PoS is more or less the mechanism used to select who get ...
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What happens when a transaction nonce is too high?

From Design Rationale: One weakness of the account paradigm is that in order to prevent replay attacks, every transaction must have a "nonce", such that the account keeps track of the nonces used ...
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A Fatal Flaw in the merge?

Maybe I am wrong and am misunderstanding something, but there is no validation done by the PoS chain. During the merge... let's say it happens at block #151... the PoW chain passes the blockchain over ...
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464 views

Why is Proof of Work, Proof of Stake associated with Consensus Mechanisms/Algorithms?

Many often associate Proof of Work, Proof of Stake, etc with blockchain consensus algorithm/mechanisms. I find that association to be inaccurate. Yes, proof of work / proof of stake are mechanisms ...
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How does ethereum network keep consistent

Since nodes in Ethereum are decentralized and distributed, how does the system ensure consistency regarding the state of the blockchain. I am aware that a validator, once they find the answer to the ...
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How does new block propagation, step by step, work in Ethereum?

I'm trying to understand how nodes propagate new valid blocks in Ethereum. Here's my attempt at a step by step how description of the process: 1. Miner constructs a new block and starts iterating ...
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Does data in memory variables get added to the blockchain? How does consensus work for memory?

If a function call involves a memory variable, does the data in memory get added to the blockchain history? If no, how come others can validate the transaction? Is the data only deleted after a block ...
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Proof of History for Ethereum 2.0

After reading about the Solana-chain, I became convinced that "Proof of History" is a great idea for syncing a decentralized clock and improving scalability. Be aware that Solana is still a ...
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What is the process for accepting an EIP?

I know the gist of how changes to the Ethereum protocol are proposed and formalized, by creating an ERC/EIP for the community to discuss and contribute to. But I'm unclear on the exact procedure for ...
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How Proof-Of-Learning can be implemented?

Seen a paper on Proof-Of-Learning and wanted to know-how the consensus works and how to implement it in ethereum?
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Proof of authority reward mechanism

Can anybody explain the reward mechanism in Proof of Authority (PoA) protocol? What kind of reward is received by the validators in PoA? So far I came up with the following points: There is no ...
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What are the most prominent dispute resolution frameworks deployed on Ethereum

Dispute Resolution may become a very important paradigm for multidimensional consensus systems such as Ethereum in the near future. In this perspective, I am going through the existing dispute ...
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What was the reason to invent the EVM?

What was the reason to invent the Ethereum Virtual Machine (EVM)? Why not use an existing virtual machine like the Java-VM. The big advantage would be that the existing toolsets for Java development ...
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Quorum Consensus - BAR (Byzantine Altruistic Rational) Fault Tolerance / BAR Fault Tolerance / BAR Model

I refer to http://www.cs.utexas.edu/~dahlin/projects/bft/ http://www.cs.cornell.edu/lorenzo/papers/sosp05.pdf http://www.cs.northwestern.edu/~fabianb/classes/cs-443-w07/BAR.pdf https://blog.ethereum....
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Transaction Finalization

According to features of the Ethereum Consensus, the rollbacks of blocks are possible: the block (and so, its transactions) is considered as a finalized one if quite a long chain is built upon the ...
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Possibility of Quantum Computing significantly speeding up transactions per second (TPS) / transaction rate for blockchain consensus algorithm?

Possibility of Quantum Computing significantly speeding up transactions per second (TPS) / transaction rate for blockchain consensus algorithm? For example, Shor Algorithm, the most complex quantum ...
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If modelling an Ethereum blockchain, would you use PoW or PoS?

I'm modelling an Ethereum network that will hopefully form part of a PhD, which will be used to identify a blockchain's functionality in certain industrial situations. I wrote my MSc dissertation on ...
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What is the consensus mechanism used in Parity for 'Proof of Authority' chains?

The Ethcore Parity wiki states that it supports 'Proof of Authority Chains'. What distributed byzantine consensus mechanism is used?
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What controls the inter-block interval in proof-of-stake?

In proof-of-work, the interval between 2 blocks is controlled by the mining difficulty: in Bitcoin, at all times, it must take roughly 10 minutes to mine a block, so every two weeks we adjust the ...
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High Block Validation

Suppose node A is running on height 2000. Node B sends to node A block with height 2002. Node A is not able to validate the block without having a block with height 2001. How does node A behave in ...
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Can the term Nakamoto Consensus (NC) be used interchangeably with Proof of Work (PoW)?

Can the term Nakamoto Consensus (NC) be used interchangeably with Proof of Work (PoW)? Which term would the community prefer to use?
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Relationship among total and bizantine number of nodes in IBFT2

According to [1]: In IBFT 2.0 networks, approved accounts, known as validators, validate transactions and blocks. Validators take turns to create the next block. Before inserting the block onto the ...
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can someone explain this line of the whitepaper?

To show how ethereum had made it's language turing-complete Vitalik in his white paper gave this example: "To show the motivation behind our solution(i.e using gas), consider the following ...
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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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Who add a ERC-20 transaction to the blockchain?

I'm totally new in the blockchain area and this problem nearly drives me crazy !In ethereum, there is a miner who was chosen by the consensus algorithm to add a block to the blockchain. I viewed the ...
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How to change the consensus algorithm in ethereum from PoW to PBFT?

https://github.com/ethereum/wiki/wiki/Consortium-Chain-Development I would like to use PBFT as the consensus mechanism in my locally deployed ethereum network. as the document specified above, we ...
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What happens if two different states of smart contract conflict?

I'm newbie studying blockchain and Ethereum. While I'm studying, I've got a question. What will happen in the case of conflict of two different states on smart contract, e.g. from the network ...
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What is the Probability of being chosen in Proof of Stake?

I'm trying to solidify my understanding of Proof-Of-Stake consensus, and one thing I've been left wondering is how to figure the probability of being chosen to be a validator. Are the chances of being ...
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What if the chosen validator down

What if the chosen validator does not create a block. How works consensus mechanism in this scenario over proof of stake
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How critical is timing to the Proof of Stake system?

I’m imagining that in the future it may be profitable for attackers to try to undermine consensus using novel means that are yet unanticipated. So I would like to contribute to speculation on possible ...
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Finality in Casper: can full node delete everything other than block header and state tree after reaching finality?

In the coming release Casper, I am assuming after Casper reaches finality, the finalized block will never reorg. Is it safe for the full nodes to delete everything (e.g., all transactions) other than ...
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Why does the Ethereum blockchain need a consensus network?

Why does Ethereum blockchain need computers to agree on blocks? If by means of cryptography, only the private key holder can generate the appropriate hash for a certain transaction, why not let a ...
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1answer
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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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Casper Engine for Private Chains

Is there a version of the Casper Proof of Stake engine either CBC or FFG that is available for testing on a private network? If so is there a guide on how I would utilize it?
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How is the state "undone/reverted" after a longer chain is determined?

So say there is block_a, and block_b, both at height 1677. And a node accepts block_a, but then recieves block_b + block_c (which is mined on top of block_b), how exactly are the state changes made in ...
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Proof of Stake leader-election [duplicate]

So I understand Proof-of-work high level, where nodes work to solve a "puzzle". And once they've created a valid block they then broadcast it to the network. So that node receives the reward ...
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Why did cryptokitties congest ethereum network when it has resizable block size?

So I am wondering how come eth network got congested when block size is resizable and it can take more trx if needed? I am reading some info that it can do that but miners don't want to do it as it ...
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In Ethereum, is it possible for a malicious client to duplicate a coin by double executing a transaction?

Is it possible a scenario in which a malicious client executes two transactions with the same nonce of a specific account and copies and sends coins? Suppose users A, B, and C have the following ...
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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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1answer
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Does more miners mean lower gas prices?

I hope the question is self explanatory but, basically I wonder if the Ethereum code is made in a way that id there is more miners, would that in turn allow for lower gas prices or transactions to be ...
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how does casper help with finality?

My question is very simple... I've watched some videos and read articles, but couldn't figure this. It's said that on the internet If the block has been finalized, it can't be reverted/changed in ...
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What is the Oracle Problem definition exactly and briefly?

What is the Oracle Problem definition exactly and briefly? Does it mean "trusting on a centralized Oracle" ? Or "How to reach a consensus between a group of Oracles" ? Is the matter "centralization" ...
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What exactly is an Ethereum client and what clients are there?

What exactly is an Ethereum client? Is it a full network node that can post transactions to the blockchain (if that is the correct lingo?) or could it also be a light JS client that connects from a ...
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2answers
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What is the difference between IBFT(Istanbul BFT) and PBFT?

I recently got to know about IBFT and Quorum and started studying on their consensus protocols. And what is the difference on IBFT and PBFT? Are they pretty much like the same and, when considering ...
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What happened in the Ropsten hardfork from Byzantium to Constantinople?

What were the consensus issues during the Constantinople hardfork in the Ropsten testnet? One noted consensus issue is: geth and parity have been in noticeable disagreement regarding block ...
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Finality in blockchain consensus

Is Absolute/ Immediate Finality a goal in blockchain consensus or does some areas work better under probabilistic finality such as Ethereum's Pow and to be PoS? (I know that some networks using BFT ...
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Block number as part of header rationale

It seems to me that block number is something that can be derived correctly by a node locally (from the parent block relationship). What was the purpose of including it in block header -> making it a ...
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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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Where is the stake amount stored in Proof-of-Stake?

So in the PoS consensus algorithm, the nodes can lock their coins and the node with the highest coins has the highest probability of getting the chance for validating coins. I have two questions: 1) ...
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How does betting on a block work in Casper?

Betting on a block is betting money that effectively says something like: "I believe that this block has at least a 60% chance of being true." Q1. Once a bet is made, is it possible to change the ...

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