Hard fork contingency plans and SegWit readiness - a challenge to solution evangelists

Currently, the biggest discussion in the Bitcoin community concerns the possible forks we might see this year - Bitcoin Unlimited and SegWit. Whether those forks should or should not be activated and whether they will create a network split is an important discussion, but what is less discussed is the risk mitigation in case either of those forks happen. I would like to post a challenge to the various solution evangelists to see if their software is ready for any outcome.

Note - some questions apply to more than one scenario. Duplicates have been omitted for conciseness.

Scenario 1 - SegWit activates before Bitcoin Unlimited

Lets say SegWit activates before Bitcoin Unlimited or any other block scaling solution takes place.

First, some questions to the Core team:

How much extra transaction throughput are you expecting to see with this solution?
Do you have any estimates as to how many transactions should move off-chain in the near future? When do you expect this solution to start reaching critical mass to alleviate the block congestion?

How many of the big Bitcoin companies will be ready for SegWit?
This important question is somewhat answered by a handy spreadsheet or two. Let's have a look and see if some important players are missing... Coinbase is "planned" so far. BitPay is nowhere to be seen. BitGo is "wip". Top exchanges - Poloniex, bitFlyer, BTC-E, OKCoin are missing. For the wallets - Armory, BreadWallet are wip, Bither, Exodus and Multibit HD are planned.

All in all, the coverage looks good, but some top players still need to get on board.

What are the fees users should be expecting?
A large pressure for the increase in the network capacity comes from the high fees to the average user. What fees should the users expect under SegWit? I've seen mention that on-chain fees will drop from 0.5BTC/block to about 0.2BTC/block, but some numbers on the off-chain fees would also be interesting.

What is the block scaling plan going forward?
Are you planning on changing the block size following SegWit? If so, when are we likely to see the size change and what would it be?

And a big question for the Bitcoin Unlimited team:

Is your client SegWit ready?
Are you ready to integrate SegWit into your client? Will it have some issues in case SegWit activates?

Scenario 2 - Bitcoin Unlimited activates first, network splits

In this scenario, Bitcoin Unlimited activates first and the network splits itself into Bitcoin Core and Bitcoin Unlimited.

Question to both sides:

How are you mitigating the damages of the split for your users?
There are many things that need to be considered when the network splits. How are you mitigating the cross-split replay vulnerability? How will you avoid the confusion when it comes to addresses being the same on both networks?

Bitcoin Unlimited devs:

Is your code ready to be pulled to Bitcoin Core?
A lot of people consider Bitcoin Core to be the "gold standard" when it comes to Bitcoin clients. Developing a different client without allowing the options to be pulled into Bitcoin Core cleanly will only make the adoption of your client harder.

So, is your code ready to create a pull request to Bitcoin Core? Do you have a branch that is up-to-date with the latest commits to Core, or will you need to catch up? If you don't have these ready, it is almost inviting a network split, rather than working on keeping the network unified.

Will you be activating SegWit on your network?
There are some good use cases for off-chain transactions - will you be activating SegWit or other soft forks required to run off-chain transactions on your network anytime soon?

How are you planning to convince more exchanges to adopt Bitcoin Unlimited?
Some developers have sworn off BU completely - for example, BitGo (and thus indirectly - BitStamp, OKCoin, Kraken, etc.), while others might be on the fence. Do you have any plans on convincing them to start supporting your software?

Bitcoin Core devs:

Will you make your client opt-in compatible with Bitcoin Unlimited?
This question was originally asked by Gavin - since "Bitcoin Core does not want to and does not make decisions on Bitcoin’s consensus rules", is Bitcoin Core prepared to let the users op-in to be able to connect to the Bitcoin Unlimited network? It shouldn't be that much work to add a flag disabling the block size check at the very least.

Scenario 3 - Bitcoin Unlimited activates first, minority network gets attacked

In this scenario, Bitcoin Unlimited activates first, the network splits, but the minority chain gets attacked by miners in hopes of preserving only one side of the fork.

Bitcoin Core devs:

What is your contingency plan for such an attack?
As I understand, the current plan is to change the PoW algorithm in a hardfork. Is that hard fork already in the works? Is the new PoW algorithm decided on yet? Has the hardfork been tested? It is a large change - you don't want to be scrambling around trying to figure this out while an attack is ongoing. Do you have your legal side of things covered? Will you be coordinating actions with important Bitcoin players, such as exchanges?

Since hardforks don't come as often, are you planning on implementing any of the hardfork wishlist items while you're at it? Will the hardfork also include SegWit?

Bitcoin Unlimited devs:

What is your plan for such an outcome?
Will you be endorsing the attack, or will you be disowning it? Are you prepared for potential legal, community, etc. backlash you might receive if the attack takes place (even if it's not of your own doing)?


There are many important questions that need to be addressed early on before Bitcoin starts forking. While we might still have some time before either fork activates, it's better to mitigate the potential risks early on than to scramble when they actually take place. I'm looking forward to developers from either of the sides sharing their thoughts on the issues raised here.


Bitcoin hard fork - if you want peace, prepare for war

Over the last few weeks we had a lot of people discussing Bitcoin forks. Every member of the Bitcoin community is voicing their opinions on the matter, so I figured I'd write down my thoughts as well.

Historical perspective

While the debate has picked up a lot recently, it's by no means a new problem. BIP101 proposed increasing the block size in mid-2015 and BIP-141 introduced SegWit in late 2015. Since then we had a number of projects wanting to fork Bitcoin - BitcoinXT, Bitcoin Unlimited and Bitcoin Classic. This is in addition to things like Sidechains, Liquid, user-activated soft forks, etc.

All in all, we can all agree (well, with some exceptions) that we need to expand the Bitcoin network transaction capacity. We can't really wait much longer - this was starting to be an issue in 2015, and now it has become a necessity.

Bitcoin slowing down

Bitcoin for a long while had the first mover advantage - everyone wanted to get into it, develop on top of the platform, etc. Being in the community early was really fun - seeing the first ATM launch, getting merchants on board, etc. However, nowadays it's a different story. Waiting multiple blocks to get one confirmation, paying over 30 cents in fees, etc. - that's not an ideal situation in comparison to what we saw years ago.

If nothing changes, we'll probably see a lot of the big Bitcoin companies expand or migrate to other platforms. Coinbase already doesn't want to pay the fees by themselves, Storj has moved to Ethereum, etc. With Ethereum's growing market cap, there are only so many reasons to stay with Bitcoin...

The fork

So this brings us to the fork situation. There is currently a lot going on in the community, but from what I can understand, there are two main camps when it comes to forking at the moment - those that want to activate Bitcoin Unlimited and soon, and those that want to get SegWit activated sometime this year.

When figuring out what can happen next, we have to keep in mind the scant few examples we had of contentious coin hard forks in the past.

From what I can tell, Bitcoin Unlimited is heading in the direction of activating its hard fork no matter what. It's ramping up in node and mining power count. It is likely that the node count is fake, and there have been some reports about the possibility of attacks on pools that don't signal Bitcoin Unlimited (by orphaning non-signalling blocks in a minority attack). There is also a concern with miners being blacklisted by the effective monopoly in mining ASICs if they signal SegWit.

Lastly, we need to keep in mind the man pushing for Bitcoin Unlimited adoption - Roger Ver. I'm not going to get into discussing his past or personality (there are plenty of trolls that have you covered), instead, lets focus on one fact - he's an early Bitcoin adopter, and he appears to be loaded. Being able to trade 130k BTC loaded. That's more than 4 times the amount of BTC Ethereum raised during its presale. So my guess is, that he could safely pay out of pocket to fund the forking effort, even if it doesn't make economic sense.

So because of this, I think the Bitcoin Unlimited will activate its fork sometime soon. Now, what will happen next?

The aftermath

It was interesting hearing Gavin's exchange with Matt on whether Bitcoin Core should have an opt-in flag to accept the possible fork or not. It looks like the answer for the time being is "no", which means the repository everyone considers to be the "gold standard" for Bitcoin will not accept Bitcoin Unlimited blocks, causing a fork.

If you want to keep Bitcoin network on only one side of the fork, you have to attack the other side. Whether that is a moral or legal way of handling the situation - it's up for debate. At any rate, 51% attack on the Bitcoin Core side of the fork is a possibility that has to be kept in mind. Luckily, there is "a nuclear option" to defend against something like that - PoW change. Since the vast majority of Bitcoin mining power is in ASICs, any change to the mining algorithm makes all of that hardware obsolete. This will mean that an attacker that has been stacking up on ASICs will end up with a large pile of useless hardware, but also that your honest miners will have the same issue.

So if Bitcoin Unlimited forks and tries attacking the Bitcoin Core side of the fork, it is likely we will end up with a PoW change fork and the unchanged, SHA256 fork. The SHA256 fork will either be kept alive by miners that oppose the Unlimited fork, or it will be left by the wayside as they will realise where the wind is blowing and switch over to Bitcoin Unlimited to maintain some income from their hardware.

Early on, the PoW fork would still be vulnerable to an attack. There are a lot of altcoin miners out there ready to put their CPUs and GPUs to work. Whether they will stand with the Bitcoin PoW fork supporters or be mercenaries for hire by the attackers remains to be seen.

If there is no attack on the minority fork, the Bitcoin landscape will probably be more peaceful, but also more divided. A number of exchanges have already signed a statement on the hard fork matter, and it looks like they will either be ignoring Bitcoin Unlimited, or treating it as an altcoin. So all in all, we'll have the Ethereum / Ethereum Classic scenario once more.

If a fork happens and Bitcoin Unlimited doesn't secure key supporters early on (miners, exchanges, developers, etc.), it is possible it will go the way of Elacoin. A coin needs to be traded and developed upon to stay relevant.


Since the fork has not yet happened, there is still some time for preparations. Every Bitcoin business will have to consider the implications of the fork on what they're doing. How will customer BTC balance be handled? How will you prepare for the relay attack? What are the edge cases you need to think about?

Even working for Factom I had a discussion about this issue, and we're not holding BTC balance for our users.

Finally, every Bitcoin user will have to prepare for the fork. Whether you decide to hold onto bitcoins at a responsible exchange, keep it in your wallet, or sell it for now in hopes of buying cheap coins during the turmoil, you should make a conscious decision on what to do, or risk getting some of your coins lost in the process.


Bitcoin needs to address its transaction throughput sooner than leter. It is likely Bitcoin Unlimited will attempt to hard fork soon. The fork will either lead to the community being divided, or an attack on the minority chain to force everyone to switch. The attack will likely lead to another fork and an uncertain future fo the minority chain. Everyone should ready themselves for the fork.

If you want peace, prepare for war.


Fourth year of /r/Bitcoin moderation

Last week marked my fourth year of moderating /r/Bitcoin . A lot has changed in the last year, but also, a lot has stayed the same. So I figured I'd make some post to collect my thoughts on our current situation and a few important events that have transpired recently.

Related topic - On /r/Bitcoin moderation - three years in review

Coinbase and the mod reshuffle

A few more perceptive readers might notice something has changed in the mod team on /r/Bitcoin - I'm claiming to have been moderating for four years, but the page only accounts for seven months. This mod reshuffle has been due to the alleged discussion between Coinbase and Reddit CEOs about removal of Theymos from the /r/Bitcoin mod team. Our top mod reshuffled the mod team to ensure BashCo would be the first in line in case he gets removed, as unfortunately Reddit has some issues when it comes to managing moderators. While not an ideal situation from my perspective obviously, I could get behind BashCo being the top moderator if worse came to worse.

So, why was Coinbase allegedly discussing removal of Theymos? That was most likely spurred by the thread coming from Theymos to label Coinbase as an altcoin service for their support of BIP 101 (the 8MB hardfork), effectively banning it from /r/Bitcoin and bitcointalk, two of the more prominent places to discuss Bitcoin.

My stance on this situation is that companies should be free to make their stance on the hard fork known without fear of being punished for it. Consensus on the hard fork comes from discussion, not from silencing dissident opinion. An opinion of one moderator should not dictate the discussion of the entire forum.

I would love to talk with Coinbase and Reddit CEOs about what issues they might have with our subreddit and how they would like to resolve them.


There is no denying it, Bitcoin blocks are practically filled by now. Some measure has to be taken in order to fix this problem soon. There have been many proposed solutions by now, including:
Unfortunately, the scaling / forking debate has become more heated recently due to a bug in Bitcoin Unlimited that crashed a lot of nodes. Following that, a lot of hostilities in the community have sprung up (along with terms like "North Corea"), and a number of exchanges have released a statement with their take on the situation. Bitcoin Unlimited is forming a Confederation with a president and getting some criticism for it.

All in all, with the rising tensions in the community, I feel like we're headed towards a contentious hard fork and a network split. We will have an Ethereum / Ethereum Classic situation on our hand. While that doesn't bode well for our current situation, it looks like Ethereum has more than recovered since its DAO incident, so there is some hope in long-term recovery...

My stance on the hard fork situation is pretty much the same as it was last year. Bitcoin needs a scaling solution, and it pretty much needs it last year. The block size needs to be increased, or perhaps even abolished one day. That being said, SegWit is also not a bad idea. It by no means should be the only solution, but it would work as a complementary approach.

As for the BU crash and the subsequent fallout, well, people make mistakes. It's unfortunate, but inevitable. Smaller teams are understandably more susceptible to unexpected crashes since there are fewer eyes on the repo and fewer people on at the same time to look out for new exploits 24/7. If any solution becomes the dominant Bitcoin implementation, it will have more scrutiny put on it. If it forks the network and remains its own blockchain, well, that's a different story entirely. It's hard for a small team to maintain a large financial system like Bitcoin.

Too little and too much moderation

A big divide in the Reddit Bitcoin communities is the issue of moderation. /r/Bitcoin moderation is generally seen as heavy-handed for obvious reasons, so a few communities have sprung up that are focused on much lighter moderation - /r/bitcoin_uncensored/ and /r/BTC being the most prominent.

It was interesting to hear some thoughts from /u/jratcliff63367 , a former /r/Bitcoin mod, when he announced his resignation from the /r/BTC moderation team. It seems that neither side of the /r/Bitcoin - /r/BTC split is sunshine and rainbows.

I could take time iterating over the various problems with both subreddits and communities, but that wouldn't be productive really. It seems like there is room for a new subreddit that would attempt to move away from the politics and take lessons from the existing communities on what to avoid, but that is neither here nor there at the moment.

My stance on the situation is that some moderation is needed, but moderation should not be shaping the discussion of potential forks. Oh how I miss /r/Bitcoin from early 2015, before the community grew more divided...


The /r/Bitcoin moderation situation for me hasn't changed much in the last year. Unfortunately, the Bitcoin community has grown more divided over the years, which makes the pressing issue of Bitcoin block debate even less civil. I hope that by this time next year something good will come of this and we'll be able to put some of our differences behind us, but I'm not holding my breath. It feels like we're heading for crossroads that will further drive a wedge between us...