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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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If you are building your own blockchain, how would you decide on the right consensus algorithm? [on hold]

Not limited to bitcoin. How does blockchain developers or businesses make the decision on which consensus algorithm to choose? What are the things to consider when deciding on the consensus ...
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31 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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35 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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31 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
33 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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32 views

Proof of Work to Create a Transaction

I make a little bit of context, so if there's something wrong in my assumptions I'll be corrected. We can say that PoW solves essentially two problems: double spending and decentralization, in the ...
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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
18 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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31 views

Byzantine Fault Tolerance Threshold of Bitcoin: 1/2 or 1/3?

According to this answer: https://bitcoin.stackexchange.com/a/58908/41513 a Byzantine Fault Tolerant (BFT) consensus threshold is 1/3, that is contrary to belief that the Bitcoin network is secure (...
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2answers
56 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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3answers
67 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
20 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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17 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
122 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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59 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
37 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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31 views

Ripple Concensus vs PBFT

If ripple only assures a consensus if less than 20% of the node are byzantine then why is it preferred to PBFT or PoW which looks like more reliable consensus algorithm
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1answer
57 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
80 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
19 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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17 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
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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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1answer
33 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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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
52 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
57 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
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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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1answer
36 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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3answers
129 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 ...
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1answer
89 views

Why was BIP34 (Block v2, Height in Coinbase) not implemented via the coinbase tx's locktime or nSequence?

At some point in 2011/12 miners started using custom mining algorithms ignoring the best practise to mine to a different new public key (hash) for each subsequent block. This lead to a lack of ...
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1answer
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Hyperledger consensus protocol

I'm soo deep inside the consensus protocols like PoW, PoS, PoA or other variants used on permissioned/private blockchains such as JPMorgan's Quorum (Based on Raft), Istambul etc.. But I've not ...
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Why is a softfork unable to divide the network?

I was wondering why a soft fork cannot in principle divide the Bitcoin network as a hard fork can. I understand that a soft fork, by definition, involves only tightening the consensus rules, but the ...
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1answer
100 views

Would nine 1MB transactions potentially create havoc on the BitcoinCash network

It appears that the BitcoinCash chain is still on its original BCH main chain, and non-upgraded mines/exchanges/wallets can still transact there. What then would happen if nine (or more) 1MB ...
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1answer
32 views

How can one full node know whether other full nodes added certain block to their blockchain?

How can one full node know whether other nodes agreed a block suggestion of a miner (so it will know whether to add the block to its blockchain too)? thank you
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1answer
48 views

How to: Check whether or not transaction inputs have been previously spent

Maybe I have overlooked it, but I think the "Bitcoin Developer Reference" does not specify how a miner has to check whether or not transaction inputs have been previously spent. How is it done? And ...
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How Ripple ledger behaves in a cross border transaction

While I was reading on Ripple, the following part of in cross border payment handling confuses me. If it's between two banks, it says that once the participating parties agree on exchange rates, the ...
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2answers
175 views

Do all consensus algorithms aim to solve the Byzantine generals problem?

Can I clarify my understanding: Byzantine Fault Tolerance is a characteristic of a system to tolerate a class of failures belonging to the byzantine generals problem. Byzantine Fault tolerance is ...
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46 views

DPOS vs tendermint in Ethereum

what is the difference between DPOS and tendermint? and which one can be used for partially decentralized blockchain ? note i will use ethereum
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2answers
54 views

Has a consensus algorithm where temporary authorities are fairly “elected” via PoW been discussed?

In the usual proof-of-work consensus system, miners constantly compute hashes (“wasting” resources). What if hashing were restricted to a certain time window, e.g., 1 hour per day? This could act as ...
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1answer
48 views

Altering Consensus Rules

How nodes agree to consensus rules? Is it possible for someone to change the consensus rules for his own software and then remain in the previous network? If not, then why?
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1answer
64 views

What happens to the blockchain after the miner wins the puzzle?

I have some problems understanding the flow of consensus mechanism, so far I know, In PoW when validating a transaction the miners will compete with each other to solve a puzzle, the miner who find ...
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2answers
64 views

What happens when a node cannot find the base Block of a newly received Block

This particular question has been bugging my mind for sometime now. Suppose there an adversary miner who mines a Block with one of his transactions. The miner would only send the updated Block to a ...
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Any attack vector for Proof of Witness?

When Alice wants to send Bob some coins all she has to do is sign a transfer of ownership with her private keys and publicize that announcement until Bob is happy with the number of witnesses. For ...
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2answers
91 views

Can an attacker use a modified Bitcoin node to pass fake transactions into the mempool?

Is it possible for a malicious attacker to download a bitcoin software code, modify that code and use that software for his own benefit? I know that any changes implemented in the bitcoin software ...
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1answer
67 views

When does a node mark a transaction as confirmed or unconfirmed?

As new transactions are broadcasted, the nodes keep them in a pool of unconfirmed transactions. One node will add it to a block as soon as it finds a proof of work. At the same time many other nodes ...
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119 views

Proof of Elapsed Time Susceptible to Random number generator attack?

Since Proof of Elapsed Time (POET) uses a Random Wait time to elect a leader, would it be susceptible to Random number generator attack? Nathan Aw
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217 views

What consensus algorithm is MimbleWimble/Grin using? Does it use Zero Knowledge Proofs as well?

Understand that MimbleWimble/Grin is privacy centric. Does it use Zero Knowledge Proofs to achieve the privacy goals? In addition, what consensus algorithm is MimbleWimble/Grin using?
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How do nodes reach consensus on when the target is recalculated?

Due to network latencies, some nodes may think they are at a different block height than the rest of the network. How then does a node decide if the target has been recalculated since that changes ...