Questions tagged [consensus]
Questions about the consensus system of Bitcoin and the protocol rules that are consensus critical.
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Why can’t the genesis block coinbase be spent?
According to the bitcoin wiki:
The first 50BTC block reward went to address 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa, though this reward can't be spent due to a quirk in the way that the genesis block is ...
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What happens if two miners mine the next block at the same time?
The process of mining as described in the answer to this question is simultaneously repeated by multiple miners.
Is it possible for two miners to find the next block at the same instant? If it is, ...
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What does the term "Longest chain" mean?
What does the term "Longest chain" mean, as there is only one 'right' blockchain exists? How another longer chain would make the 'right' chain invalid?
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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 ...
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How is a blockchain split resolved?
Let's say two miners created 2 different blocks and broadcast them into the network. Now some clients see blockchain 1 and other blockchain 2 which are different from each other.
I would like to ...
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What is proof-of-stake?
As we know one of the important mechanisms of Bitcoin is proof-of-work.
How does the concept of proof-of-stake work? How does it differ from proof-of-work?
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What happens when a miner does not claim all fees/generated coins?
Suppose that a miner for some reason has the generation transaction of their blocks not take all the possible coins. This can happen for a variety of reasons, almost all of which are bugs:
An off-by-...
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Do "the official bitcoin developers" control Bitcoin?
Is there one person or organization that controls Bitcoin?
What if Gavin Andresen, the lead developer, or Bitcoin Foundation, "the official bitcoin organization", decide to change something? What if ...
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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 ...
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What are the pros and cons of Ripple's consensus as compared with Bitcoin's proof-of-work?
One of the major differences between Bitcoin and Ripple is how they process transactions. I can think of three ways in which Ripple's "consensus" scheme is superior to Bitcoin's proof-of-work:
Less ...
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Are there alternatives for proof of work?
Bitcoin uses proof of work to secure the network, Ripple uses a global consensus system and PPCoin uses proof of stake.
Are there any known alternatives to the above methods?
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Byzantine fault-tolerant consensus - Why 33% threshold
Can somebody tell me why in dbft the threshold is 1/3 for malicious nodes? I mean that seems pretty abitrary. I have no problem if it is abitrary but is it?
Note: I'm not referring to Bitcoin. I chose ...
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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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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 ...
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Bitcoin without mining
Several months ago I've stumbled an interesting question about the Ripple system: How does Ripple solve the double-spend problem?
Specifically about how double-spending is solved in Ripple. As you ...
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Why are banks and other centralized entities interested in block chains?
Apparently banks and other centrialized entities are interested in block chain technology. My question is, why?
The whole point of block chains is for decentralized, trustless, consensus. Bitcoin, ...
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Why exactly would adding further divisibility to bitcoin require a hard fork?
There are quite a few threads already on this topic, but they all focus on the necessity or possibility for such a change. I understand that, even though it is difficult and would obviously require ...
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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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What is the exact consensus protocol Ripple uses? [closed]
Ripple supposedly incorporates transactions into the ledger using a consensus protocol. I have been looking everywhere for a clear, formal, and precise specification of the protocol and could not find ...
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Who decides the block reward in Bitcoin?
I know that when a miner mines a block, he will be rewarded with some bitcoins. But who decides how much bitcoin he will get? If it is decided by all the miners (as they are the ones verifying ...
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Why isn't the upper bound (+2h) on the block timestamp set as a consensus rule?
Why isn't the +2h acceptance rule part of the consensus? Of course, then it couldn't be based on network-adjusted time + 2h because, in edge cases, one part of the network might accept something while ...
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How to calculate the BIP34Hash?
I know this going to be a repeat question, however I am still puzzled with the implementation of the BIP34 especially where it come to its hash.
Referring to the chainparams.cpp at github :
https://...
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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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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?
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Restarting mining on new transaction
I understood that when a new transaction comes in, the miners have to start over, or at least change their merkle-tree to include the new transaction, essentially starting from scratch again.
If I ...
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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 ...
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How does Proof of Burn work?
I have been trying to make a comparison between PoW, PoS and Proof of Burn. While I understood the other two, I want to know how exactly Proof of Burn helps in attaining the consensus.
One burns ...
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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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Was the addition of OP_NOP codes in Bitcoin 0.3.6 a hard or soft fork?
I'm doing some deeper research into historical consensus changes and it seems like most folks consider the addition of the OP_NOP codes to be a hard fork. Here's the diff for their addition: https://...
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Why bother having limitations on Bitcoin Coinbase Transaction Scriptsigs?
There are a few limitations on the structure of the coinbase (reward) transaction in a block.
There is only one input. vin.size() == 1 (source)
It doesn't reference any previous output. vin[0]....
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What does 'signal' and 'lock-in' mean in a BIP?
I have a vague idea about the jargon used over there, but what exactly do 'signal' and 'lock-in' mean specifically?
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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 ...
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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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Is the minimum fee consensus, just policy, or both?
Intuitively, I think minRelayFee is policy while minBlockTxFee is validation, but DEFAULT_MIN_RELAY_TX_FEE is in validation.h while DEFAULT_BLOCK_MIN_TX_FEE is in policy.h.
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What is the logic (if there is) behind linking the nSequence and nLockTime?
The nSequence transaction field was originally intended for a replacement logic, but since it was never well thought out, it was never implemented. However, it has been implemented since the beginning ...
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Why can malicious miners not award themselves with any number of bitcoins?
Why can malicious miners not award themselves any number of bitcoins? Is that because the award itself is a transaction which has to be confirmed by a random miner? And if so, what if the miner ...
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How many blocks per second can sustainably be created using a time warp attack?
In a time warp attack, an attacker can reduce proof of work difficulty to its minimum, which allows even a single piece of modern mining equipment to create large numbers of blocks per second. ...
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Was it always required for the Coinbase transaction to be the first transaction in a block?
The user tempo mentioned on another topic:
"At least in the early protocol versions it was possible to put the coinbase transaction not on the top of the outputs."
I have never heard about this ...
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Ripple Distributed Consensus Algorithm
What kind of a Consensus Algorithms does ripple use? Is that a leader or leaderless distributed consensus algorithm? Then what?
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where is difficulty target inserted?
All miners at any time must have a consensus on the "difficulty target" to be able to achieve the correct nonce (as answer of proof-of-work).
Assume that the target has been updated (it means that ...
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Where can I find a complete list of Bitcoin forks (soft, hard, intentional and unintentional)
I was looking to study the history of Bitcoin forks including the 2013 incident that may or may not have been a Hard fork depending on your definition.
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Is there actual consensus on the blockchain's tip or only until the next block?
Using this scenario https://bitcoin.stackexchange.com/a/40435
Let's say we have two competing blockchain tips: They both start from
Block A as a parent, but then there are two different blocks ...
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Should a node follow the longest chain, or the chain with most work while syncing?
I'm reading mixed things online - some saying to follow the longest chain, and some say to follow the chain with the most work. But I'm not convinced of the former.
If the node follows the longest ...
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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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What is Delegated Proof of Stake (DPoS)?
I know that it is a consensus algorithm that is different from Proof of Work (PoW) and Proof of Stake (PoS) which is used in a few blockchains including but not limited to STEEM, BitShares and ARK, ...
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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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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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Does the reference client Bitcoin Core determine the consensus rules?
Does the reference client Bitcoin Core determine the consensus rules? Why should we care what is in the BIP if when there is a discrepancy between the BIP and the Core codebase (like we saw recently ...
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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 ...
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Miners setting timestamps up to 2h into the Future
When a miner adds the Timestamp to a block template, it must satisfy two conditions:
Timestamp must be greater than the Median Timestamp of the previous 11 blocks
Timestamp must be less than its ...
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