Questions tagged [consensus]

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

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12
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3answers
6k views

How can we trust supply won't be increased in 2140 by just a few lines of code?

How can we trust supply won't be increased by just a few lines of code?
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1answer
1k views

If two miners come up with two valid nonce's, how does consensus take place?

I am trying to understand how the consensus mechanism works. My understanding is that multiple nonce's can satisfy the target hash requirement. What I'm trying to understand now is: if two miners come ...
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4answers
86 views

If the nodes are what keep Bitcoin decentralized, what if some big internet company spun up 60%+ majority nodes?

If the nodes are what keep Bitcoin decentralized, what if some big internet company spun up 60%+ majority nodes? What’s stopping them from manipulating the blockchain to change transactions?
0
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1answer
40 views

How many people are needed to make a decision to increase Bitcoin money supply? [duplicate]

Yes, it is currently capped at 21m. But it is just a line of code. Anybody can go and change it to whatever they want and what is needed then is to persuade the miners to accept it. Blockchain ...
7
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1answer
152 views

CVE-2012-2459 , possible code and performance improvement, is my logic correct?

ok so, in my effort to create a fullnode from scratch both for learning purpose and need (not a topic for discussion, thanks), I was looking at the code that check Merkle Root to not be vulnerable to ...
2
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2answers
380 views

Can Bitcoin nodes vote to increase the money supply beyond 21 million?

Is it possible for 51% of the Bitcoin nodes to pool and vote to increase the money supply limit? Is that allowed in the protocol?
2
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3answers
245 views

Could the threat of centralization be realized if a sufficiently large entity acquired enough Bitcoin?

This is primarily a hypothetical, but not an impossible one. If a sufficiently large entity such as a massive company with a lot of cash or the U.S. Federal Reserve were to acquire more than half of ...
5
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4answers
2k views

Would Bitcoin still work without a target difficulty?

Suppose that Bitcoin nodes had no target difficulty at all, and instead just accepted the block with the largest PoW every 10 minutes. Ignoring the increased bandwidth (since nodes would be ...
1
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2answers
196 views

Would an optimization proof-of-work problem where the entity with the lowest hash wins have any security weakness or other disadvantage?

I am wondering if there would be any security deficiencies if cryptocurrencies such as Bitcoin were to change their proof-of-work problems to optimization contests. For example, suppose Bitcoin were ...
1
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2answers
44 views

Will Nakamoto consensus work if a nontrivial portion of miners/nodes are on the moon? [duplicate]

Will Bitcoin (or Nakamoto consensus) work if a non trivial portion (say 5%) of miners/nodes are on the moon? What about mars? How about one of the moons of Jupiter? If not, why not? If yes, how does ...
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1answer
48 views

Noob question: Why is there not a limit of the number of blocks in a chain revision?

I have a noob idea and I want to understand where I'm going wrong :) Say nodes agreed on a block revision limit, say, 6. This would mean that if they see an incoming chain that is longer than the ...
0
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0answers
21 views

What are the options to recover from 51% attack purely from algorithmic standpoint

Assuming there exists a malicious entity, they have managed to own 51% hash power, and executed a sustained 51% attack on Bitcoin, say 24 hours. In this case : What are the options then to recover ...
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3answers
527 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 ...
7
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4answers
1k 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,...
0
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1answer
71 views

1-CPU-1 Vote Bitcoin confusion

How does the 1-CPU-1 vote works because if we're talking about miners doing computation power to vote, then successful solver of the hash wins the block, so basically only the single cpu (considering ...
0
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2answers
50 views

If there was an easy way to check for double spends, will consensus algorithms be needed?

Currently, checking for double spends is very computationally expensive, so consensus algorithms, like POW, were put in place to more easily prevent double spends among other things. Ignoring the fact ...
2
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1answer
96 views

What is the benefit of having a fixed target block interval?

By design Bitcoin targets a block interval of 10 minutes. How does the blockchain benefit from maintaining a bounded block time?
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2answers
133 views

Decreasing Energy Consumption of Bitcoin's PoW with paired mining rounds

I found the following whitepaper on an algorithm called "Green-PoW" by the authors and i'm quite sure this would be a perfacet solution and also would get acceptance by the miners and the ...
1
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1answer
327 views

Does pruning affect a node's security or consensus ability?

An SPV node certainly is a compromise of security because the full set of consensus rules are not verified by the node (for example block size or subsidy rules). A pruned node seems like a win-win, ...
1
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1answer
47 views

Who enforces new consensus rules in Bitcoin?

I have been reading at few places that miners will enforce new consensus rules. Examples: https://twitter.com/BitMEXResearch/status/1391014115968274433 https://twitter.com/ajtowns/status/...
1
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1answer
164 views

51% attack, miners, nodes or both

If 51% of the hashrate was controlled by bad actors mining invalid blocks, this would become the longest chain. Where do nodes come into the 51% attack? The canonical chain is the longest chain. Is ...
11
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2answers
6k views

Bitcoin without mining - what needs to be implemented

I have read this related question - Bitcoin without mining and I am trying to understand the very basics of Bitcoin network and the blockchain. I wonder, if we take the mining out of Bitcoin, what ...
9
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2answers
3k views

Is there a maximum size of a scriptSig/scriptPubKey?

Previous research: Transaction's maximum size What is the maximum size of a transaction? The maximum size of a standard transaction is 100k bytes. Are there any consensus rules that prohibit ...
6
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4answers
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 ...
1
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1answer
94 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/...
1
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1answer
62 views

How are malicious forks resolved?

I understand that forks are resolved by opting in for the eventual longest chain, preferring the chain with the longest POW. But everything I read on this suggests it's just random chance or that the ...
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1answer
57 views

Preventing secretly mined chains

In order to prevent attackers from secretly mining chains (which they could later publish to perform double-spending attacks), would it be possible to require some information to be included in the ...
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1answer
53 views

Why does the value range of outputs need to be restricted?

In the 'tx messages' section for protocol rules we have Each output value, as well as the total, must be in legal money range For each input, if the referenced output does not exist (e.g. never ...
1
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1answer
25 views

How does the blockchain prevent transaction based on outdated note

This question borders along the line of cryptography and distributed systems, but I guess I have a strong chance of getting an answer if asked here. So here goes: I understand that the blockchain is ...
0
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3answers
332 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 ...
1
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1answer
59 views

Can the forked be unforked?

So: BTC, BCH, BTG and BSV all trade at different prices/values. All have forked off from BTC and have different development teams, theories, practices, technology, etc. I noticed that when you look ...
4
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1answer
307 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
33 views

how is bitcoin network protect itself from malicious nodes? [duplicate]

Can someone explain how does Bitcoin network protect itself from malicious nodes? Lets say someone creates bitcoin core clone and they manipulate it to their need. For example could someone change ...
1
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2answers
731 views

Can a blockchain's transactions be reversed?

Blockchains are often described as 'immutable' (meaning the history cannot be rewritten after the fact), but is this really true? How easy is it to change the history? I have read about the Ethereum ...
-2
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1answer
102 views

Can cryptocurrencies like Bitcoin be turned into a censored payment system under that would be financial regulation framework creating soft forks? [closed]

It s well known mining pools as well as hashing power is centralized in countries where electricity is cheap and using mining farms rather belonging to at least medium sized companies than single hand ...
2
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0answers
157 views

Ripple: only a sub-network reaching a consensus is largely enough to be decentralized&secure system? [closed]

I spent a while reading ripple protocol, specially the consensus process, the protocol works based only on a sub-network ( from a huge network) reaching a consensus for the current state, it's ...
3
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2answers
308 views

Who is the decision body for forking a blockchain ledger?

Is it fair to compare the decision body responsible for forking a blockchain as 'escrow officers'? How can users of the blockchain network dare to the treat the distributed ledger as immutable as long ...
3
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1answer
85 views

What is the difference between Consensus and Distributed Consensus?

This is more of a clarification than as a question. Since I didn't have the rep to post a comment in this question, I'm putting this itself as a question. Sources I've referred till now: A ...
7
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2answers
597 views

How does the BTC protocol guarantee that a "main" blockchain emerges?

I'm reading up on the bitcoin/blockchain technology. Usually, the part about proof of work and how to create a block is well explained. However, what is never explained is how/why the communication of ...
1
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2answers
269 views

Will the 1MB block size increase in the future?

The current Bitcoin block size is 1MB and is generated every 10 minutes, therefore 7 transactions per second. If the use of Bitcoin increase in the future, is the 7 transactions per second going to be ...
1
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4answers
971 views

Is mining the unfair part of bitcoin in the same way banks (or rather, fractionary reserve systems) are to current monetary system?

I've been reading a lot about bitcoin lately and I'm very interested. Especially, when it comes to making a currency that is way more fair, because it avoids a centralized control of it. However, in ...
-1
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1answer
109 views

How does the blockchain know if its block hashes have been tampered?

I'm dealing with some problems to finally understand how implicit consensus works and I've come across with one question. Suppose the following: A malicious miner proposes the following block to be ...
3
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3answers
556 views

How exactly are Bitcoin's consensus rules enforced?

There are some rules called consensus rules, for example the block generation amount. And it is said that "a change to consensus rules is a hard-fork". But how exactly are the consensus ...
0
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2answers
55 views

How is difficulty enforced in the bitcoin blockchain? [duplicate]

Is it through some sort of voluntary acceptance by miners or is it hardcoded into the bitcoin blockchain to not accept a block which doesn't achieve a given difficulty level?
3
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1answer
358 views

Difference between PoW and BFT

What is the difference PoW algorithms (as used in Bitcoind) and BFT (used for instance in Libra) ?
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1answer
49 views

How a transaction is permanently accepted by the blockchain?

If a miner A creates a block containing a transaction A and a miner B creates a block NOT containing the transaction A about at the same time, then some of the other miners will first receive the ...
1
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2answers
76 views

What exactly makes altering of data in non-bitcoin blocks hard?

If leading zeros is only bitcoin requirement, then what makes altering of data in blocks hard? Like now its easy to modify a block and generate new hash for every subsequent blocks since generating ...
8
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2answers
2k views

How do Bitcoin devs make sure that their modifications do not affect the consensus rules or the running network protocol?

I understand that Bitcoin consensus rules are enforced by every single node individually. However, most people run the default version of Bitcoin Core, which makes the implementations done by Bitcoin ...
1
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1answer
161 views

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

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 ...
4
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2answers
242 views

what if the timelock is in the past?

I just started learning about bitcoin scripting and wonder: what if the timelock in CLTV is in the past? what if the timelock in nLocktime is equal to 500.000?

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