Bitcoin Forum

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I haven't heard one good reason to upgrade to SegWit. Just a bunch of nonsense about the network not being able to scale. Seems to be scaling just fine to me....

Is the whole network going to crash if there is a million unconfirmed transactions? I don't think so.

Where did all the SegWit supporters come from all of a sudden? Many users registering in the last month all of a sudden know everything about why Bitcoin needs SegWit.

Segwit fixes transaction malleability, which means that a transaction composed entirely of segwit inputs will have only 1 txid. This makes it easier for services to track deposit transactions because then there is no need to actively watch for any malleated transations and track those as well. Those malleated transactions would be considered a double spend and ordinarily rejected.

Segwit also makes sighashing[1] a linear operation instead of quadratic with a new algorithm. This reduces the effect of a large transaction taking a long time to verify. Note that such a large transaction has happened before. A transaction was created a few months ago that was 1 MB in size. It was created by a miner and included in the miner's next block, i.e. not broadcast until confirmed. This transaction took ~30 seconds to confirm, which, in computer time, is an incredibly long time.

Segwit makes hardware wallets to their jobs better. The new segwit sighashing algorithm includes the value of the output being spent from so hardware wallets can easily verify whether the transaction that it is signing is valid. This helps with further verification done by the wallet itself prior to signing the transaction.

For the full list of what segwit does and its benefits, see https://bitcoincore.org/en/2016/01/26/segwit-benefits/

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[1] Sighashing is the process where all of the transaction details are prepared and then hashed. The hash is then signed and the signature goes into the transaction.

What's wrong with a rejected transaction due to double-spend?

It's only happened to me 3-5 times in over 3 years after thousands upon thousands of transactions. And usually it is because I am impatient and I broadcast a new transaction before downloading the entire blockchain.

In regards to malleability that is such a non-issue that it does not warrant switching Bitcoin into a completely new Altcoin "SegWit"

When you complicate things even more that are "highly technical" you end up with more issues like "malleability" that compound problems later.

Bitcoin is working just fine, who is to say SegWit does not open the door for other problems that you people who think you are smarter than Satoshi fail to foresee...

The issue is that there are two or more transactions, and the service is only watching one of them because it only knows about that, the malleated ones are rejected. If a malleated version of that transaction confirms, the service does not know about that because it does not see the original non-malleated one in the blockchain and does not credit any deposit even though the Bitcoin has been sent and confirmed.

Additionally, when a transaction is malleated, you actually run into an issue with wallets. Most wallets allow you to spend unconfirmed change because it is reasonably sure that the unconfirmed transaction to be spent from is trustworthy and will confirm, because you are the one that sent it. A lot of wallets do that. The problem happens when you go to spend, and you end up spending from unconfirmed change. If the original transaction is malleated and then the malleated transaction confirmed, whatever transaction you just created is now invalid and the recipient now will not receive any Bitcoin, and if they spent from that unconfirmed transaction, then neither will anyone else down the chain.

This case with the wallets is an issue and is hard to deal with when writing wallet software. This has happened to me a few times when people were malleating every single transaction they received and broadcasting those.

Compound what problems?

Satoshi failed to foresee a lot of things. Satoshi is not a god and all knowing creator that we should worship. We should not just take what he gave us and use only that, we should fix things that we see are broken and iterate on and improve what he gave us.

It is not necessary.
But would surely be more useful than e.g. the payment protocol.

What is it about malleability that is such a big problem? In the almost 7 years of Bitcoin's existence, I am only aware of two "companies" that have claimed to have been negatively affected by malleability, and I believe both of them are/were lying (I know for sure that at least one of them is lying).

I would think that a more common sense fix to the sighashing "problem" would be to limit the number of SigOps allowed in a transaction, as I do not think there are many "business reasons" why any given transaction would ever need to have a large number of SigOps.

Malleability is an issue for off-chain scaling solutions such as the Lightning Network.

I understand that, but that is not how SegWit is being "sold" to Bitcoin users! What achow101 et al is saying is that SegWit is fixing his horrible malleability "problem" and will help Bitcoin scale with a defacto block size increase (via a discount in how much space SegWit signatures take up), but are leaving out the fact that LN/thunder cannot function without SegWit.

LN can function without segwit. It is just a lot more complicated and has a few more failure scenarios. With segwit, its implementation is much simpler.

If there are failure scenarios then I don't think it will work very well, nor do I think many people will be willing to even give it a try.

There are failure scenarios in everything. Not having segwit for LN introduces a few more possibilities for failure (if coded improperly) than without segwit. Not having segwit requires more complexity and thus a higher possibility of a bug.

I have thought about this, and I cannot think of a way that LN can work without malleability being removed from Bitcoin, and without additional forks of any kind, and meeting the criteria of the ability to have instant, trustless, two-way transfers. If you want to explain how LN might work, then be my guest.

From a technical perspective, in a vacuum, LN should work once malleability is removed, assuming a client can be programmed in a way that it cannot be tricked into signing transactions "out of order". From an economical perceptive, I am not so sure for a couple of reasons.

Here's my position, if Bitcoin is not good enough As-Is then why don't you all get together and create a better Alt-Coin?

Oh that's right you can't. So if you can't create a better Alt Coin then why screw up Bitcoin?

depends on what you consider big -> https://bitcointalk.org/index.php?topic=1198032.0

In pretty much all cases, this was nothing more than a nuisance to end users. I have not read any reports of any entities losing money as a result of that attack (some may have lost potential revenue as a result of not being able to accept 0 confirmation transactions, but I would not consider that in the scope of 'losing money as a result of that attack')

Subsequent to that 'attack' the majority of nodes have been "programmed" to not relay high s-value signature transactions, so malleability has more or less been fixed for the end-user. The only way that I am aware that a high s-value signature transaction to get confirmed is for a miner to accept such transaction directly and the only type of business that remains vulnerable to malleability are gambling establishments that allow for on-chain gambling (businesses that tentatively accept 0-confirmation transactions can ignore transactions in which there is an unconfirmed input to the funding transaction in order to prevent fraud). 

Same as the "spam attacks", yet somehow a lot of people think we need to do something about that in order to advance bitcoin.


No, its not fixed. We just ignore all transactions. This causes issues for users using old software.


Its working, yes. Is that the metric here?

The spam attacks cause everyone to pay more to get their transaction confirmed. If the max block size were increased then the cost of these spam attacks would grow exponentially, and the effectiveness of these transactions to decline. 

You can say the same thing about every soft fork. However users of non-full-node wallets should receive notification that their transactions have been rejected, which should hopefully get them to upgrade. Full node users tend to be more active in upgrading, however they can view their transactions (or that their transactions have been rejected) on one of many block explorers, which might get them to upgrade in addition to the warning message to upgrade.

Non-upgraded users will probably not receive high s-value signature transactions because other upgraded nodes they are connected to will not rebroadcast such transactions, and because the overwhelming percentage of users will not even attempt to broadcast such transactions.

I am not sure what you are saying here? I am trying to describe the small number of businesses that are affected by malleability under current node rules.

A mere inconvenience, same as having to wait for a confirmation in order to make sure you can trust the input. Both have a cost, one in time, the other in coins.


They get messages alright, usually the message gives them no indication what to do though. You can blame that on bad error messages, its still a problem.


38% are currently running the latest version -> https://bitnodes.21.co/dashboard/?days=90

Old data are not shown (or only as other) so I cant say how long it exactly took until the network had upgraded to the mellability quick fix, but thats all it is. Im not inclined to believe that node operators are not more active in upgrading, unless you can show me data to support that statement.


SegWit is not needed, its not necessary, Bitcoin would still exist and work without it. SegWit however properly fixes a long term problem that keeps coming back and is currently crudely fixed. It also offeres many opportunities for a larger number of different transaction types. The increase in transactions per block doesnt hurt either.

Bitcoin is expanding because it is a fantastic payment system, but it does not have the ability to become the dominant world payment system. There would be too many transactions for it to handle. It is the most sophisticated payment sytem in my opinion, and it has the potential to become even more sophisticated. SegWit allows it to incorporate these changes, and to keep the blockchain manageable. For this reason alone, I think SegWit is desirable, the other advantages are icing on the cake.

Take a look at this (not just quote, but whole post):
or at this discussion:

And btw, let's think who is interested in spreading FUD about Segwit and LN, going as far as making ridiculous statements such as 'segwit is an altcoin'?

Should Bitcoin as it is now go mainstream, even with 20 MB blocks it won't be able to process daily payments of average Joe. So business of payment processors such as Visa will be unaffected. Nothing prevents them from being able to process payments denominated in Bitcoin just like they do it now with USD. That means of course that people will have to put their BTC in banks, fractional reserve banks precisely speaking. So Visa's business is unaffected, bank's business is less affected. Well it's a little conspiracy theory, don't take it too seriously.

The way bitcoin works is more akin to a settlement layer, not really a payment processor processing thousands of small-size transactions per second. I think we will need off-chain scaling solution to achieve mainstream if you want to maintain the useful properties that bitcoin has today.

That's what we are more or less talking about.

Why do we need Lightning Network again?

Because we need to scale 1000000x solution. Not fucking 2x or 10x.

We need really cheap micro-payments.
We need INSTANT micro-payments, faster than 0.1 second.
We need SECURE INSTANT micro-payments.

We need BTC for 1 000 000 000 users, not for fucking early adopters, who does not understand how segwit/LN work, but they have their fucking opinion...

Agreed.  I'm sick of paying 25 cents worth of Bitcoins in fees to pay $20 to an online retailer and having to wait 19 hours for 1 confirmation.

It should be fast.
It should be cheap.
It should be perfect.

SegWit and LN are the best proposals so far that I have heard that can help towards achieving these goals.

Any side-chain can do that and it wouldn't need to modify the bitcoin protocol. So. As a maleability "fix" it's a bit of a sledgehammer to crack a nut with a rather large cost in data storage and distribution. The question is then; why is the tail wagging the dog?

Well, would you say that all the knowledgeable people (such as Andreas Antonopulos) are randomly saying that segregated witness is a must to be activated before we plan in increasing block size? those guys make a living out of knowing how bitcoin works, if all the best minds in the game agree that segwit is good, there must be something about it right? im not saying blindly believe the experts, do your research, but the fact the experts agree should tell you something already.

Why does someone have to convince you that progress is necessary for innovation to continue?

Stagnation and it's subsequent results should be enough motivation. Change is a part of life, I prefer to be on the right side of it.