What is SegWit?

[solarcrypto]

Novice Question. What is SegWit? Why is it a big deal

 

[Manfred]

Segregated wittiness is the offspring when breeding Bitcoin with xrp by establishing (banking) connection, which can be declined, like a bank account)

Bitcoin SV and (Bitcoin Cash) are pure breed Bitcoin. (Thoroughbred versions, Pedigree Bitcoin)
Segregated Witness Bitcoin is a half-breed mongrel

 

[solarcrypto]

@Manfred interesting. I've been seeing it a lot lately with most asking for support of it. What do you think about it?

 

[Manfred]

^^^ Who is asking for support of it?
Segregated witness (lightning) is pure slave money. A payment channel is for life. So in 10 years time when you want life insurance the insurance company will tell you so many cigarettes did you buy, this and that brand and this many crates of beers, so it will cost you ....
You have to do anything to keep every established channel, losing one can mean losing another or worst case all. Without payment channel you literally starve to dead.
Now when you have open bills on one phone company the other will refuse to deal with you (some countries). In a digital environment everything is interconnected not just particular branches.
With Satoshis Bitcoin you create a new addresses and the simple filtering of the database features of segregated witness (lightning) is not possible, especially if you start mixing .......
At least 6 exchanges it dialed with which no longer exist, manual tracing is cumbersome and can not be compered to all payment channels i would have with segwit.
At this stage i think Bitcoin cash is implementing something like lightning, so the number of coins free of it is thinning especially if you take in long term (guaranteed) deflation aspect of satoshi bitcoin.
How far down the list of thousands of coins you have to go to find 5 coins with just this 2 attributes?
With atomic swaps the whole thing becomes the biblical "one world currency"

 

[Robin Hood]

What is SegWit?

Well the man with the beard who more or less single-handed wrote the code could tell you.
If you get a honest answer is another matter.

 

[TierNolan]

Novice Question. What is SegWit? Why is it a big deal

Segregated witness is a method to fix transaction malleability. Malleability makes chains of transactions unsafe.

Imagine you had a chain of transactions that weren't submitted to the blockchain.

A spends from B and B spends from C

With transaction malleability, they can be changed after you submit them. Anyone who gets a transaction can modify it to make a different version. This means that as your transaction propagates over the network, some nodes could modify it before sending it onwards.

They can't change where the money is sent, but they can alter a valid signature into another valid signature.

Transactions refer to each other using txids. B would refer to C using C's txid (transaction id).

When you submit C, if it is modified by someone before it makes it to the miner, then it will have a different txid (even a tiny change alters the txid).

C' (modified C) could get accepted by the block chain if that miner gets the next block.

This means that B and A are now worthless. B spends from C, not from C', so it won't be accepted, even though it has a valid signature.

The way to fix this problem is to ignore signatures when referring to other transactions.

C and C' are identical, except for signatures. The unsigned txid is identical for both and can't be changed without invalidating the signature. If transactions referred to each other using the unsigned txids, then the malleability problem would go away.

This is a hard forking change, so was resisted by those who have object to hard forks on principal.

An alternative is to just remove all the signatures from the transactions. If transactions have no signatures, then inherently, the unsigned txid is the same as the normal txid.

Obviously, if people didn't have to sign their transactions, then the security of the whole system would fail.

Segregated witness was born. It has two parts. First, all signatures are remove from the (segwit) transactions and second, the signatures (witnesses) are all placed in a separate (segregated) data structure.

Note: the signatures are still checked with segregated witness. That is part of the point.

This is a soft fork and so was promoted by those who want to avoid unnecessary hard forks.

Fixing malleability is a reasonable goal. The objection was mostly that it would have been better to simply fix it with a hard fork.

The easiest change would have been to allow transactions to refer to the previous transactions by either the signed or unsigned txid. This would have required an extra database key for the unsigned tx though, so it wouldn't have been free.

Note2:
Segregated witness transactions actually include both the normal (legacy) transaction and the witness data as a expanded transaction.

These combined transactions are placed in the block as a single unit. These transactions have to be split apart and the witness goes into one merkle tree and the legacy transaction is used for the main merkle root.

 

[Peter R]

@TierNolan

It's funny I see this comment from you this morning. Last night I spent hours going over old bitcointalk threads, and I was asking myself "what happened to TierNolan?"

When reading your comments from 2012 - 2015, I am always amazed at how much thought you gave to bitcoin and the foresight that you had. Everything I work on seems to have been already thought about in detail by yourself.

 

[TierNolan]

It's funny I see this comment from you this morning. Last night I spent hours going over old bitcointalk threads, and I was asking myself "what happened to TierNolan?"

Nothing specific. My interest waned somewhat, especially when progress basically stopped due to the block size debate.

I wonder if the big block side should have formally proposed the extension blocks hard fork. It would have only required majority miner support. It would have given potentially unlimited block size. It would have meant accepting that avoiding hard forks is worth an increase in complexity/technical debt.

Heh, maybe you could get miners to support it even Today .

When reading your comments from 2012 - 2015, I am always amazed at how much thought you gave to bitcoin and the foresight that you had. Everything I work on seems to have been already thought about in detail by yourself.

Those were really interesting discussions. The high quality was due to lots of smart people and a very high signal to noise ratio.

Bitcointalk was such an awesome forum in its day. The torching of a neutral meeting point was such a loss. Any new location is always going to be seen as for one side or the other.

With hindsight, I think that the blocksize debate was an example of "compromise is not an option". The disagreement was between those who prioritize personal chain audibility and those want a low fee currency. This is something that reasonable people can disagree on.

A compromise would be to increase the block size but at a slower rate. That is what segwit2X attempted.

Eventually, that gives a block size that is to small for low fees and a block size that is to large for home users to verify the chain back to genesis. It is a lose/lose option. Neither side gets what they want in the end.

A compromise is worth it when it benefits both sides. It is better to get 70% of what you want by compromising then to "go to war" and have a 50% chance of getting 100% of what you want. In this case, compromise would mean neither side gets what it wants. The small block side realised this early, I think.

Any compromise would have had to acknowledge the inevitable chain split. A negotiated splitting fork would have meant much less disruption. They could have shared the ticker symbol (e.g. 1 BTC counts as 1 of each of the two forked chains). They could even have released a client that works for both chains with a command line flag (or even both at the same time).

This would have kept the network effect rather than dissipating it. The chains could have been identical except for the size. Software that was compatible with one would automatically be compatible with the other.

 

[Roger Kruger]

SegWit is the process by which the block size limit on a blockchain is increased by removing signature data from Bitcoin transactions. When certain parts of a transaction are removed, this frees up space or capacity to add more transactions to the chain.

 

[AdrianX]

Segwit is a change to the Bitcoin consensus rules, a change made by a "soft: fork resulting in a change to teh consensus rules that most nodes can't detect. It segregates signatures from transactions and introduced other features not necessarily good for incentivizing on-chain transactions.

This talk by @Peter R does a good job of discussing some of the pre Segwit concerns.