Gregory Maxwell

At a recent SF Bitcoin Developers meetup, Bitcoin Core contributor and Blockstream CTO Greg Maxwell provided a technical presentation on the upcoming 0.15 release of Bitcoin Core. During the Q&A portion of his talk, Blocktime co-host Michael Tidwell asked Maxwell for his thoughts on SegWit2x and specifically what he thinks would happen in a situation where the hard fork portion of the proposal gains majority support from the network hashrate.

SegWit2x came out of the New York Agreement where large Bitcoin companies and the vast majority of the network hashrate agreed to implement a hard-forking increase to the block weight limit in November; however, some signers have already backed out of the deal or clarified that they were never for the hard fork portion of the agreement.

In his response to Tidwell’s question, Maxwell noted that the major contributors to Bitcoin Core are not interested in SegWit2x and will not implement it.

“I think it’s unlikely that [SegWit2x] will get more work behind it for the same reason that miners are mining [Bitcoin Cash] right now,” said Maxwell of the prospects of the proposal. “Miners are going to follow the money.”

The ‘Most Work’ Chain is Not What Matters

From Maxwell’s perspective, Bitcoin is defined by the rules of the system rather than the desires of the majority of the network hashrate.

“More work is always secondary to following the rules of Bitcoin, said Mawell.”

To further his point, Maxwell noted that there may have already been situations where Ethereum has had more joules of energy pumped into its mining process than Bitcoin.

“I don’t just suddenly go, ‘Oh, Ethereum is Bitcoin now because it’s got more joules of energy pumped into its security,’”

It is Possible for Bitcoin to Hard Fork, But It’s Hard

Although Maxwell is against the SegWit2x proposal, he did concede that it is possible for Bitcoin to hard fork in the future.

“But it has to be a hard fork the users as a whole choose to do,” Maxwell clarified. “Maybe that’s really hard to achieve, especially since we can do so many things without hard forks.”

The contributors to Bitcoin Core tend to prefer soft forks over hard forks because they’re backwards compatible and can be rolled out on an opt-in basis.

“That’s an important part of the security model because if you can easily change Bitcoin to take one controversial, probably okay change, then you can change it in lots of other ways as well,” Maxwell added.

According to Maxwell, bitcoin’s value proposition is as a “digital asset that isn’t going to change out from under you”.

In terms of the types of hard forks that could work, Maxwell noted that one potential process is to add a soft-forking change to Bitcoin and then use a hard fork to clean up the technical debt related to the change at a later date. Maxwell believes it would be much easier to gain social consensus around these sorts of hard forks.

“There is a proportional relationship [between] the distance you have to the code — and the operation of the system — and how viable you think some of these proposals are,” Maxwell later added about hard fork proposals more generally.

How Would Bitcoin Core Contributors React to SegWit2x?

In terms of how the contributors to Bitcoin Core may react to SegWit2x gaining the majority of the network hashrate, Maxwell first reiterated that the proposal would probably only gain majority support from miners if users as a whole were adopting it.

“I think that if users as a whole were adopting it, then the people that are developing Bitcoin today would go and do something else instead, said Maxwell”

In a situation where the majority of miners are supporting SegWit2x and users still prefer the original chain, Maxwell noted that a change to Bitcoin’s proof-of-work algorithm (SHA-256) would “make sense”. The Blockstream CTO does not view SHA-256 as a defining trait of the Bitcoin system, and he noted that it may need to be changed in the future for security reasons anyway.

Changing the proof-of-work algorithm would effectively destroy the investments bitcoin miners have made into specialized hardware used for the mining process. Maxwell referred to this as a “nuclear option”.

“When you have no other choice, you do it because duh,” Maxwell added. “Do you choose a system that’s non-functional and insecure or do you choose a system that works?”


    • You guys are welcome to create as many altcoins as you want. Bitcoin will still be Bitcoin. You are delusional if you think either Bcash or JeffCoin is going to become Bitcoin just because some malicious miners decide to mine it.

      • Your answer means you didn’t understood what bitcoin is all about.
        It means that anyone have the FREEDOM to clone it.
        It means that anyone can IMPROVE it.
        And lastly, it means that if the miners (how come miners are “malicious”?) are going to mine this clone, the legacy chain could die.
        And if that happens, you can thank the devs of the legacy chain.

        Oh and btw, there is no such thing as Bcash.
        Bcash is a term coined SPECIFICALLY to strip the word bitcoin out of Bitcoin Cash.

        • I didn’t understood? lol ok.

          Listen, of course they can clone it as much as they want, but if they don’t include replay protection, and try to pass of either Bcash or JeffCoin as Bitcoin, then it really is an attack, and that makes those miners malicious.

          As long as the trusted devs that have been developing and maintaining Bitcoin, are still running Bitcoin, and the users who trust them, also run Bitcoin. you guys can run whatever you want, but it won’t be Bitcoin unless it’s in consensus with the core nodes. It really is as simple as that.

          I bet Bcash and JeffCoin will survive in some shape or another, and that’s ok, just don’t try to fraudulently pass it off as Bitcoin.

          And as for the Bcash name, yes of course it’s a name real bitcoiners use for the chinese clone coin instead of “Bitcoin Cash”. It is for exactly that reason, strip out the name Bitcoin, simply to avoid confusion.

          This is Bitcoin:

          Bcash and Jeffcoin is not, and never will be, Bitcoin.
          You r/btc numpties should start facing reality lol.

          • “As long as the trusted devs”
            This clearly proves my point.
            In a trustless, open source system you don’t have to trust anyone. You check the code and run it.

            By the way B-I-T-C-O-I-N C-A-S-H (that’s how is spelled for the mentally impaired) actually have replay protection. Did you know it? Of course not, you can’t even spell stuff correctly, probably a sign of your poor reading skills and general understanding of how cryptocurrencies works

    • It can be a mixed POW, with dsha256 in the mix. The scenario is that the hardfork gets not 51% of the hashrate because then you can just keep where you are. They are under the threat of wipe-out, not you.

      If the hardfork gets 60% hashrate, it’s still not dangerous for the original chain, as the forking miners cannot at the same time attack the legacy chain and maintain the new chain. For that they would need at the very least 70% but even a 70%/30% split between HF and legacy would not warrent to go for the nukes right away. It would just warrant to keep the briefcase with the code close by.

  1. Bizarre arguments. The idea of Bitcoin was clearly that the longest chain with most PoW is the valid chain. On the other hand, Maxwell argues that the ‘true Bitcoin’ must follow the ‘rules’. According to this, the longest chain would never be relevant to determine if something should be changed. This is arguing against the core idea of PoW. PoW is no longer how you measure consensus.

    Then he says: “But it has to be a hard fork the users as a whole choose to do. Maybe that’s really hard to achieve, especially since we can do so many things without hard forks.” This is indeed hard to achieve. But that is because there is no way of measuring what users want and absolutely no process around it. PoW is Bitcoin’s process to come to consensus. Of course, it’s impossible to reach consensus if you get rid of the only process you have to reach consensus.

    But it is very convenient to have a nebulous ‘what users want’ sword to wield against anything.

    This soft-fork / hard-fork distinction is also super questionable. So SegWit got activated in a soft fork and now all the wallets will implement it. As a user, I have zero voice in if I want that or not. Maxwell may be able to construct some twisted arguments how this is ‘opt-in’, but it certainly doesn’t feel opt-in to any actual users. On the other hand, in a hard-fork with replay protection like Bitcoin Cash I can sell whichever side I don’t want. There is a real choice there.

  2. Blockstream and friends has ruined Bitcoin. Instead of doing what was necessary (increase the blocksize to handle the increased demand), they worked on SegWit. While SegWit might be a good thing in the long run, it was not what was necessary for the health of Bitcoin, and they should have postponed it. If they had increased the block size and done a hard fork (which they seem to be petrified to do), then we wouldn’t have Bitcoin Cash or the possibility of another hard fork (SegWit2x). In my opinion these guys let the Bitcoin community down for the last 2 years and should be removed from having any authority in the Bitcoin community. They do what THEY think is in THEIR best interest, not what the community wants.

  3. let’s get back to 3D cards:
    block -> huge translucent multicoloured polygon set -> OpenGL rendering -> SHA256 on top of that

  4. The users have chosen to hard fork.

    Why do you give airtime to the prat who with the help of a few other idiots has been instrumental in dividing the bitcoin community and handing market share to Ethereum and other players ?

    Greg and luke deserve to be ostracised for the damage they have done to our community.


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