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Questions tagged [consensus]

Questions about the consensus system of Bitcoin and the protocol rules that are consensus critical.

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How does the 51 percent or 2/3 majority voting rule work?

For a block to be added to the chain, it needs vote from majority of miners, is that correct? If yes, does that mean a single block gets worked upon by all of the miners?
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1answer
20 views

Proof-of-Stake: What if a bad enactor is chosen by random?

My understanding of proof-of-stake is the following: The node that mines the next block is chosen, randomly in proportion to the amount of nodes they have in the network (ex. person who who owns 5% ...
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1answer
23 views

How do nodes come to consensus on whether a timestamp is valid?

From bitcoin wiki: A timestamp is accepted as valid if it is greater than the median timestamp of previous 11 blocks, and less than the network-adjusted time + 2 hours. If a miner submits a block ...
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16 views

PBFT vs. Proof-of-Authority?

based on this answer: https://bitcoin.stackexchange.com/a/79402/41513 : PBFT (Practical Byzantine Fault Tolerance) is a voting based consensus algorithm in which every node must send messages to ...
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1answer
47 views

What are the biggest Proof-of-Stake roadblocks? [closed]

What are the biggest hurdles (technological or otherwise) that the Proof-of-Stake consensus algorithm must overcome to become the de facto consensus algorithm for blockchain? Or put differently, what'...
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1answer
23 views

What is meant with 'the highest PoW'?

What is meant when the nodes select the chain with the highest cumulated PoW? How is the highest highest PoW calculated? I thought the concept itself is called PoW.
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1answer
132 views

Activation of SegWit v1

The segregated witness soft fork of August 2017 included a versioning field which would allow for future incrementation. Anthony Towns has recently posted an early draft of the proposal for the SegWit ...
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0answers
10 views

Ripple: Validators

All the validators need to reach consensus in ripple. Would it that mean that, the more validators there are, the slower the process results? But the less validators there are, the more unsafe the ...
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2answers
29 views

Does a Node connect to all the peers?

Does a Node connect to all the peers in the network? Or just a few? If its just a few, how many? If its just a few, what about if all of those nodes in the list are malicious?
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1answer
12 views

Blockchain: How do nodes know what Data is correct from Consensus process?

How do nodes know what data is correct from consensus? What about if two nodes execute two different consensus with 2 different Valid blocks with the same height at the same time, can that happen? ...
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1answer
22 views

as a individual miner's side, how UASF, UAHF agree or disagree is occurred?

UASF is timestamp-based method. after that time, new rules will start. but i have a few question about this. how this rules is accepted by USER? does miner program contains 'yes' or 'no' about this ...
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Does everything of a Blockchain Network rely on its underlying “Consensus Protocol”?

I have been reading about and researching on Blockchain Technology for quite a while now, and what I can comprehend from the very primitive architecture of these "Distributed Databases" is that ...
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0answers
18 views

How is the fault tolerance measured?

“If the number of nodes that agree exceeds 2/3, the blocks or transactions of clients will be accepted” Practical Byzantine fault tolerance (pBFT) : (n - 1) / 3 I read those 2 things in a PDF that a ...
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0answers
16 views

Byzantine Fault Tolerant - what a benefit? [duplicate]

According to wiki, if we had m generals, than we need 2m+1 to meet consensus. So it's about 66.6% + 1 generals But what the reason to use consensus like BFT? Why we can't get result of the most (50%...
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0answers
15 views

Private Blockchains: Blocks’ validation

I’m a software developer and I’m trying to understand blockchain at a code level I have the following issue: There’s a private blockchain, this private blockchain does not have any relation to ...
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1answer
23 views

Private Blockchains: Validation

I'm a software developer, and I have some questions about private blockchains, I'd like to have technical answers since I'm trying to understand blockchain at a code level. I'm going to write a ...
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2answers
48 views

Proof for “Is an immutable, decentralized blockchain possible without economical incentives?”

Bitcoin is immutable because of economical incentives. Those who are able to 51% the network can't do it, because it'll result in the value of the currency to drop tremendously, which causes waste of ...
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1answer
23 views

Bitcoin Pluggable Consensus with Algorand? [closed]

Algorand is an extremely promising consensus protocol -- Could Bitcoin be configured to use Algorand?
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34 views

On blockchain scalability bottleneck

It is often said that the major bottleneck of blockchain scalability is that every (honest) node has to process every (valid) transactions. But the progress of a blockchain is how fast it reaches ...
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0answers
114 views

Did the introduction of VerifyScript cause a backwards incompatible change to consensus?

My question is about the changes to bitcoin done by commit range [a75560d8, 6ff5f718], and their effect on consensus. Out of this range of four commits (all attributed to satoshi) during the dates ...
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0answers
32 views

Why is PoW 51% attack resistant?

I was trying to understand why PoW makes the blockchain 51% attack resistant. From my understanding, we can think of PoW as a way to assign a leader who would decide what the next block is. I can see ...
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0answers
39 views

What is the best way to test new consensus protocol?

I wanted to test a new consensus protocol. However, the bitcoin core is a large codebase (>100k lines). Is there any small codebase which is designed to test new consensus protocols and includes only ...
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0answers
43 views

Why Spectre has a “weak” liveness?

According to this article: (https://medium.com/@avivzohar/the-spectre-protocol-7dbbebb707b5) written by one of Spectre's author (Aviv Zohar), it is mentioned that Spectre has weak liveness. What is ...
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2answers
133 views

Exact definition of “Liveness” and “Safety” properties in a consensus?

Two main properties of a consensus are "Liveness" and "Safety". What are the exact and precised definition of "Liveness" and "Safety" properties in a consensus ? Are the following definitions ...
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1answer
45 views

Is there a max number of tx outputs allowed by consensus? [duplicate]

It seems good for preventing an UTXO bloat by restricting max number of outputs of TX(or block) can have. Is there such a restriction? if there is, which part of source code should I read? If not, why ...
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0answers
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Does the BFT solution from lamport guarantee liveness?

Solution: https://people.eecs.berkeley.edu/~luca/cs174/byzantine.pdf Although there is a lot of material about this, I am still not sure what the answer is. I found two different statements: Yes, it ...
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1answer
37 views

Bitcoin economic nodes, concensus, and historical nodes

With regards to the recent dos + inflation bug, and seeing that most nodes on the network have still not upgraded with the patch (lukedashjr's chart here: https://luke.dashjr.org/programs/bitcoin/...
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1answer
116 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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2answers
66 views

Do miners become temporary dictators of blocks they mined?

This is something I've read here: https://blockgeeks.com/guides/bitcoin-forks-guide/ "When a group of miners discovers and mine a new block, they become temporary dictators of that block" Can anyone ...
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2answers
274 views

Why didn't Bitcoin implement segwit in the first place?

Why didn't Bitcoin implement segwit in the first place? Why and how does non-segwit Bitcoin enable a miner to change a transaction's txid? From Mastering Bitcoin ch. 7 § "Transaction identifiers": ...
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3answers
177 views

Game Theory in Blockchain?

The blockchain consensus seems to be very related to the Game Theory, when each participant tries to achieve their "favorites", where defining "what favorites means" is not very easy, since a ...
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1answer
61 views

Tendermint consensus: Are validators “known” and “pre-selected”?

What are similarities and differences between Tendermint consensus and Proof-of-Stak? For example, in both consensus, a validator is selected randomly (I think in Tendermint consensus they are ...
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0answers
36 views

Leader election-based Blockchains public?

Consensus protocols such as those of Tendermint, Red Belly Blockchain or Algorand can be of great help when dealing with the problem of Finney attacks, and similar sorts of abusing of excessive 'thing'...
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1answer
26 views

Bitcoin version conundrum

Given that the Bitcoin node software not centrally controlled (auto updated) and many different versions and implementations exist around the world, how would a core change be possible if it is not ...
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1answer
182 views

Is PBFT a consensus algorithm?

Can we consider PBFT (Practical Byzantine Fault Tolerance) as a consensus algorithm ? And if yes, How does it work? And is it similar to other consensuses such as PoW, PoS or PoA ? Or it is totally ...
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1answer
129 views

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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1answer
52 views

Consensus roles for op_return

What is the validation rule, not policy, for op_return? What is the maximum length of the data that can be attached? Is it 514 bytes? As if the maximum script size was 520 bytes -1 byte for the ...
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1answer
84 views

How to select a leader in RAFT consensus protocol

Suppose a network of 5 nodes uses RAFT consensus protocol. Each nodes maintains a transactions log which consists of a list of the log entries. Each log entry again consists of index and term. All of ...
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1answer
101 views

the maximum possible entries a network can accept in RAFT consensus?

Suppose a network of 5 nodes uses RAFT consensus protocol. Each nodes maintains a transactions log which consist of list of log entries. Each log entry again consist of index, term and command. The ...
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1answer
24 views

How is the amount of proof-of-work invested in a chain calculated?

The bitcoin whitepaper (page 3) states The majority decision is represented by the longest chain, which has the greatest proof-of-work effort invested in it. I could not find how exactly this ...
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35 views

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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“consensus over state” vs. “consensus over events”?

Does someone know what is difference between "consensus over state" and "consensus over events" ? I found just title of a reference i.e. "Ian Grigg, blog post “The Message is the Medium,” 2017." ...
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1answer
61 views

Delegated Proof of Stake (DPOS) vs. Proof of stake?

What is the main difference between Delegated Proof of Stake (DPOS) vs. Proof of Stake? Is there any significant advantage for security? (since PoS in general suffers security problems.) And which ...
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2answers
112 views

Do private blockchains need consensus protocols?

My understanding is that in a private blockchain, the participating nodes verify and agree that the block is valid and only then add it to the blockchain.In this scenario, are consensus protocols (...
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3answers
813 views

How is Bitcoin governed by mathematics?

I keep hearing talks from Bitcoin evangelists that claim Bitcoin isn't governed by any central authority, rather it's governed by mathematics. What exactly do they mean when they say "governed by ...
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1answer
73 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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2answers
90 views

Is it logical to use “Proof-of-Authority” for a “public” blockchain?

According parity.io website: Proof-of-Authority is a replacement for Proof-of-Work, which can be used for private chain setups. And also: The chain has to be signed off by the majority of ...
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3answers
447 views

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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39 views

Distributed Consensus

"Distributed" means operating on more than one devices which dont share physical memory and perform their task (which might be storage or computation) to perform one single task (which in our case ...
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145 views

Has PoS really been proven secure under comparable assumptions as Bitcoin?

I am just reading this paper which claims to be a formal proof that Cardano's latest Ouroboros PoS protocol ("Genesis") gives similar security guarantees than Bitcoin's PoW protocol. Unfortunately, it ...