Who decides if a code change is a "hard" fork or a "soft" fork?

ranochigo

legendary

Activity: 3038

Merit: 4418

Crypto Swap Exchange

Quote from: BlackHatCoiner on May 16, 2021, 12:58:34 AM

Yes, it seems that in Bitcoin, the miners can actually vote for a network rule change, in contract with what this forum says. Roll Eyes

Quote from: bitcointalk

It is a common myth that Bitcoin is ruled by a majority of miners. This is not true. Bitcoin miners "vote" on the ordering of transactions, but that's all they do. They can't vote to change the network rules.

Technically, it is not wrong. Miners can signal their support for various protocol changes to ensure a smooth transition for any soft forks or hard forks. It is always better to have support for all of the parties involved in the network before implementing any significant changes. But it doesn't necessarily mean that we need their consent in order to change any network rules. UASF was something that was proposed after the miners were not willing to signal support for Segwit and it would've resulted in a forced activation of segwit without the participation of majority of the miners.

Most of the soft forks were MASF, up to this day. But it doesn't mean that we strictly require the miner's consent to implement any network changes, though that would potentially introduce certain side effects for non-upgraded nodes, etc.

pooya87

legendary

Activity: 3472

Merit: 10611

Quote from: BlackHatCoiner on May 16, 2021, 12:58:34 AM

Quote from: pooya87 on May 15, 2021, 10:42:47 PM

For example if all miners decided to do a malicious fork today it won't be accepted by anyone and they would be mining something worthless and their chain won't grow because all nodes (except the ones that they run) will reject their chain.

Wouldn't that be a special case? If all miners decided to do that, then there wouldn't be any miners left for the “correct” chain. Even if the Bitcoin nodes left, that simply relay information, reject the malicious change, how would the old chain be extended? Wouldn't they be forced to either accept the new miners' chain or hard fork the already existent?

That is an extreme example for an extreme case so obviously it would also require extreme actions to mitigate it, something such as an emergency patch to do something about the difficulty manually or even in a more extreme case to change the mining algorithm.
In reality malicious changes only have a minority support (eg. bitcoin unlimited or bitcoin cash) and they are simply rejected by the super majority. Worst case scenario is a slower main chain until the difficulty adjustment.

Pmalek

legendary

Activity: 2730

Merit: 7065

Quote from: bitcointalk

Bitcoin miners "vote" on the ordering of transactions, but that's all they do.

This isn't really the best place to talk about this, so hopefully OP wont mind that I am kind of hijacking his thread to ask this question. But since you mentioned the ordering of transactions, something crossed my mind.

I was reading about PoH yesterday. I am not sure whether to call it a new type of consensus mechanism or a type of hybrid PoS model. Anyway, the idea is that each transaction is ordered based on a timestamp by a decentralized network-wide clock within milliseconds. Thus, miners don't have to vote on the ordering of those transactions and the network is lightning fast. I am not going to mention which alt uses such a model, but I did find it an interesting approach. Would like to hear what those with more technical expertise think about it.

BlackHatCoiner

legendary

Activity: 1512

Merit: 7340

Farewell, Leo

Quote from: pooya87 on May 15, 2021, 10:42:47 PM

For example if all miners decided to do a malicious fork today it won't be accepted by anyone and they would be mining something worthless and their chain won't grow because all nodes (except the ones that they run) will reject their chain.

Wouldn't that be a special case? If all miners decided to do that, then there wouldn't be any miners left for the “correct” chain. Even if the Bitcoin nodes left, that simply relay information, reject the malicious change, how would the old chain be extended? Wouldn't they be forced to either accept the new miners' chain or hard fork the already existent?

Quote from: rekumit on May 15, 2021, 10:23:28 PM

I think I understand - so a soft forked version of the protocol will only be accepted if a threshold of miners broadcast the version with their block.

Yes, it seems that in Bitcoin, the miners can actually vote for a network rule change, in contract with what this forum says. Roll Eyes

Quote from: bitcointalk

It is a common myth that Bitcoin is ruled by a majority of miners. This is not true. Bitcoin miners "vote" on the ordering of transactions, but that's all they do. They can't vote to change the network rules.

pooya87

legendary

Activity: 3472

Merit: 10611

Quote from: rekumit on May 15, 2021, 10:23:28 PM

I think I understand - so a soft forked version of the protocol will only be accepted if a threshold of miners broadcast the version with their block.

Essentially that is what it all comes down to, 1 CPU 1 Vote. But it is slightly more complicated than that. You see bitcoin is not just the miners, it is all the people that are using it. More specifically the full nodes that are securing the network and the economy that is built on top of it.
For example if all miners decided to do a malicious fork today it won't be accepted by anyone and they would be mining something worthless and their chain won't grow because all nodes (except the ones that they run) will reject their chain.

rekumit

newbie

Activity: 12

Merit: 0

Quote from: pooya87 on May 15, 2021, 09:56:50 PM

Whenever something is changed in consensus rules through a soft/hard fork, in a decentralized system like bitcoin the consensus has to be reached before that change can be accepted. That means having the majority accept that change by "casting their votes" which is done by miners changing their block versions to show their "vote".

I think I understand - so a soft forked version of the protocol will only be accepted if a threshold of miners broadcast the version with their block.

pooya87

legendary

Activity: 3472

Merit: 10611

Quote from: zbig001 on May 15, 2021, 05:09:37 AM

"A hard fork removes or relaxes consensus rules."
Your old client sees these blocks as invalid, I bet.

"A soft fork introduces a new rule or makes the rules more restrictive."
Your old client cannot validate all block content, but recognizes the block as valid.

This is wrong. A fork can do either whether it is considered soft or hard. The distinctive factor that makes one soft fork and the other hard fork is backward compatibility. In other words if all the nodes have to upgrade to continue syncing then it is a hard fork, otherwise if they can still validate without needing to upgrade then it is a soft fork.

Quote from: rekumit on May 15, 2021, 11:19:17 AM

Thanks, this is helping me understand. So the only way to "soft fork" is to change the validation function and have the majority of miners pick it up? The result being that the most prevalent validation function used by the miners being the most likely to produce the longest chain?

Whenever something is changed in consensus rules through a soft/hard fork, in a decentralized system like bitcoin the consensus has to be reached before that change can be accepted. That means having the majority accept that change by "casting their votes" which is done by miners changing their block versions to show their "vote".

rekumit

newbie

Activity: 12

Merit: 0

Thanks, this is helping me understand. So the only way to "soft fork" is to change the validation function and have the majority of miners pick it up? The result being that the most prevalent validation function used by the miners being the most likely to produce the longest chain?

TryNinja

legendary

Activity: 2758

Merit: 6830

Quote from: rekumit on May 15, 2021, 09:49:14 AM

How does that work? i.e. How does the software determine if a change to the protocol is backwards compatible?

If you change the block size limit to 10 MB and try to mine one with this size, the other nodes will see your block as invalid because they have a rule that says so. Meanwhile, your "10 MB" nodes will see the block as valid and will propagate/keep them between themselves. Congrats, you just forked the blockchain through your own hard fork.

If your change still produces valid blocks (that follows the rules) in the eyes of everyone else (the older versions), then it's a soft fork.

rekumit

newbie

Activity: 12

Merit: 0

Thanks for the answers everyone.

So if I'm understanding correctly, the distinction between a "soft" and "hard" fork isn't made by a human or humans. It's determined by the technical implementation. How does that work? i.e. How does the software determine if a change to the protocol is backwards compatible?

zbig001

member

Activity: 162

Merit: 19

"A hard fork removes or relaxes consensus rules."
Your old client sees these blocks as invalid, I bet.

"A soft fork introduces a new rule or makes the rules more restrictive."
Your old client cannot validate all block content, but recognizes the block as valid.

ABCbits

legendary

Activity: 2870