Questions tagged [consensus]

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

Filter by
Sorted by
Tagged with
39
votes
3answers
16k views

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 ...
49
votes
2answers
22k views

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, ...
26
votes
2answers
15k views

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?
3
votes
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 ...
5
votes
2answers
2k views

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 ...
28
votes
1answer
12k views

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?
17
votes
1answer
1k views

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-...
11
votes
3answers
1k views

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 ...
6
votes
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 ...
23
votes
2answers
5k views

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 ...
11
votes
3answers
4k views

Byzantine fault-tolerant consensus - Why 33% threshold

Can somebody tell me why in dbft the threashold 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 ...
18
votes
3answers
5k views

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?
9
votes
2answers
1k views

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, ...
7
votes
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,...
7
votes
1answer
1k views

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 ...
3
votes
1answer
356 views

Difference between PoW and BFT

What is the difference PoW algorithms (as used in Bitcoind) and BFT (used for instance in Libra) ?
12
votes
2answers
2k views

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 ...
9
votes
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 ...
4
votes
1answer
457 views

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 ...
3
votes
1answer
2k views

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://...
1
vote
2answers
253 views

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 ...
13
votes
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?
11
votes
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
votes
3answers
6k views

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 ...
9
votes
3answers
904 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 ...
6
votes
2answers
520 views

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?
4
votes
1answer
986 views

Ripple Distributed Consensus Algorithm

What kind of a Consensus Algorithms does ripple use? Is that a leader or leaderless distributed consensus algorithm? Then what?
3
votes
2answers
1k views

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 ...
2
votes
1answer
1k views

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, ...
7
votes
2answers
596 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 ...
4
votes
1answer
496 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 ...
4
votes
4answers
3k views

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 ...
3
votes
1answer
97 views

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 ...
2
votes
1answer
63 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 ...
0
votes
1answer
92 views

Some miners set the nVersion field of the block header to 0x8000004. What were they signalling for? Was this an error?

Some miners set the nVersion field of the block header to 0x8000004. What were they signalling for? Is this an error? I have been through a lot of the BIP documentations, but cannot seem to find any ...
0
votes
2answers
199 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 ...
-1
votes
3answers
115 views

Vulnerability of Bitcoin Network

Hi all I was wondering if I am doin a wrong assumption here: Let's assume a dezentralized peer to peer network and the bitcoin protocol. If a full node changes a transaction within a block and then ...