Questions tagged [segregated-witness]

This tag should be used for questions regarding Segregated Witness (segwit), an activated softfork that defined a new transaction format which doesn't include signatures in the transaction identifier (txid).

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5
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3answers
258 views

Why is the witness data fee discounted by a factor of four?

I've read that it encourages users to consolidate UTXO sets. How would it be doing that?
5
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2answers
285 views

Can unupgraded nodes that accept zero confirmation be fooled after SegWit?

Considering the following scenario: After deployment of SegWit, there remain two old clients (with software that is unaware of SegWit) A & B. A funds a transaction to pay B using a SegWit ...
5
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2answers
2k views

P2WSH, witness_v0_scripthash: how to derive an address

Is there an address associated with P2WSH scripts? for testnet txid =6717c8971dccbf826790efc16fb357f1e225fed3448247b8556c9f13a6c0ce42, i get: "vout": [ { "value": 0.05994165, "n": 0, ...
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2answers
166 views

What were the main technological reasons that Bitcoin Cash did not want to adopt SegWit?

What are the key risks/drawbacks to SegWit and why did the Bitcoin Cash community conduct a risky hard fork to avoid it?
5
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2answers
461 views

Has UTXO selection methods changed since activation of Segwit?

Before Segwit, transactions were penalized higher fees for having more inputs than outputs due to the input size being larger despite those transactions actually decreasing the global UTXO set. Segwit ...
5
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1answer
377 views

SegWit and previous hash: txid or wtxid, or either?

With segwit there will be two transaction ids wtxid and txid Can either one of them be used as previous hash or only txid?
5
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2answers
205 views

What is the point of including the scriptCode of the input in the transaction digest of segwit?

BIP143 specifies "a new transaction digest algorithm". scriptCode of the input (serialized as scripts inside CTxOuts) What problems could arise if the scriptCode of the input were not ...
5
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2answers
320 views

Why didn't Bitcoin implement segwit in the first place?

Why didn't Bitcoin implement segwit in the first place? Why and how does non-segwit Bitcoin enable a miner to change a transaction's txid? From Mastering Bitcoin ch. 7 § "Transaction identifiers": ...
5
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1answer
772 views

Qualities of “Pay to Nested Witness Key Hash”

The lightning dev tutorial mentions the np2wkh or Pay to Nested Witness Key Hash address type, and I would like to find out more about it, so far without success. Can anybody explain how they are ...
5
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1answer
547 views

What are the standard formats of transaction outputs?

A transaction output can have the type Pay to public key hash, P2PKH, where the ScriptPubKey field has the format: 76 a9 14 <20-byte hash of pubkey> 88 ac Pay to script hash, P2SH, used for e.g. ...
5
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1answer
2k views

Segwit address creation

I'm unable to create a segwit address in Bitcoin Core 15.0.1 64-bit Windows I have tried multiple times but keep getting the same error. The following is the output from the console $ getnewaddress ...
5
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1answer
831 views

Why does BIP141 define both virtual transaction size and weight?

Why does BIP 141 (segwit) define both virtual transaction size and weight? Weight seems to be just four times virtual transaction size (or vice versa, depending on what you define first). Why are ...
5
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1answer
752 views

Can old wallets redeem segwit outputs it receives? If so how?

There's some conflicting information out there on whether this is true or not. I'm looking for a technical answer to this in the hopes of clearing up future potential confusion over the matter. The ...
5
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2answers
71 views

Why SHOULD the funding tx consume BIP 141 inputs?

In BOLT 02 we read that the funding TX should only consume segwit inputs. The sender: when creating the funding transaction: SHOULD use only BIP141 (Segregated Witness) inputs. What is the reason ...
5
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1answer
651 views

(dis)Advantages of migrating funds to segwit?

For offline pre-segwit wallets (addresses starting with 1) what might be the advantages of migrating or not migrating to segwit (addresses starting with 3)? Even though segwit miner fees are or will ...
5
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1answer
508 views

What is 'ScriptCode'?

I don't understand what the 'ScriptCode' thing is. Is it a part of transaction format? The wiki https://en.bitcoin.it/wiki/Transaction describes scriptPubKey and scriptSig, mentioning nothing about '...
5
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1answer
755 views

Why does the Segwit developer guide recommend to estimate fees on basis of vsize instead of weight?

The Segwit Wallet Development Guide has a small section on fee estimation: Transaction Fee Estimation Instead of transaction size, a new metric is defined, called “virtual size” (vsize) ...
5
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1answer
318 views

What is it that makes BIP149 safer to activate than BIP148?

There are currently two BIPs floating to enable a "user activated softfork" of Segregated Witness. BIP148 is meant to activate by flag day on August 1st 2017 whereas enforcing nodes stop accepting ...
5
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1answer
1k views

Generate paper wallet SegWit address

I am trying to generate SegWit paper wallet address from WIF: My WIF is L5mHKZsCLS27nSoGM3RdAwuxjvg7XhJdP25LgqdXe6zF11wpWdbT. I am converting WIF to compressed public key: Compressed public key: ...
5
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2answers
468 views

How does a SegWit node verify a block?

I know that non-SegWit node could verify a block without witness. For SegWit node, is witness necessary to verify a block? Because I know witness are committed as wtxid merkle node in coinbase. What'...
4
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3answers
3k views

What is the Witness and what data does it contain?

I've learned about the Segregated Witness but couldn't find info on breaking it down. I know usually when legacy addresses are used the public keys for example will be under Scriptig. With P2SH, I ...
4
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2answers
854 views

Segwit transaction from mixed addresses (segwit and non-segwit)

Is it possible to have partly segwit transactions? I.e. some utxos from segwit addresses and some from non-segwit addresses. Asking for the situation of Bitcoin core v0.15 wallet with coins in segwit ...
4
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2answers
244 views

Is there a reason big Bitcoin companies wouldn't use only SegWit transactions?

As I understand, SegWit allows anyone to create a SegWit address where they can send their bitcoins and transact from that wallet just as easily as they would with a traditional address. The SegWit ...
4
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2answers
1k views

Birthday attack on P2SH

The Segwit Benefits document has this to say about P2SH security for base transactions: Multisig payments currently use P2SH which is secured by the 160-bit HASH160 algorithm (RIPEMD of SHA256). ...
4
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2answers
2k views

What is block weight and how is it different from block size?

While reading about BIP141, I have encountered the following options: Block creation options: -blockmaxweight=<n> Set maximum BIP141 block weight (default: 3000000) -blockmaxsize=<n> ...
4
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1answer
83 views

How has the Bitcoin average block size recently risen above 3 MB?

I was aware that the block size could rise above the 1 MB cap due to SegWit. However, my understanding was that the block size would still be limited under SegWit. My understanding of SegWit is that ...
4
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2answers
187 views

On chain cost of Segwit version 1 versus version 0

How do total blockchain cost for Segwit version 0 compare to version 1 which is being proposed? I'm specifically interested in a single user transactions – both paying to public key (or pk hash) and ...
4
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1answer
106 views

Does v1 Segwit includes v0?

My question is whether the version 1 of Segwit script will allow you to use version 0 scripts types inside of it. In other words, is version 1 superset of version 0? Please include reasoning behind ...
4
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1answer
774 views

In simple terms, what are the major differences between P2WPKH and P2WSH bech32 addresses?

I've read over the bip173, bip141, and bip143 specifications and they're a bit too technical to get at the simple answers I'm looking for.
4
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1answer
845 views

How to compute SegWit txid?

BIP141 says wtxid is SHA256 of [nVersion][marker][flag][txins][txouts][witness][nLockTime]. Is data that hashed as txid includes witness? And will txid be presented in block, e.g. be counted when ...
4
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1answer
564 views

Can a Non-Segwit Miner mine segwit transactions?

I understand that non-segwit nodes interpret segwit txes as Anyone-Can-Spend txes, and they cannot validate txes that spend segwit outputs. But when an old style miner receives a segwit tx to mine he ...
4
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1answer
114 views

Does any current SegWit or blocksize increase proposal also seek an increase in the OP_RETURN byte limit?

Does any current SegWit or blocksize increase proposal also seek an increase in the OP_RETURN byte limit? https://en.bitcoin.it/wiki/OP_RETURN Are there any current pull requests that seek an ...
4
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1answer
71 views

Why is a minRelayTxFee of 1000 sat/kb not equivalent to 250 sat/kw?

Naively, we would expect a minRelayTxFee of 1000 sat/kb to correspond to 250 sat/kw. However, apparently this is not so according to this issue (ACINQ), which also references this issue (c-lightning). ...
4
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1answer
105 views

What differences exist between the Lightning Network implementation versus the white paper?

I'm reading the Lightning Network WP and came across SIGHASH_NOINPUT, then came across this: Lightning network: how was malleability actually fixed? Are there any other design considerations in the ...
4
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2answers
876 views

Can someone explain how this person hacked bitcoin?

I'm trying to fill a few gaps in my understanding how this transaction happened! It all started with this article In short, some vigilante/miner was able to scoop up all of the BCH sitting in ...
4
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1answer
1k views

What does “NODE_WITNESS (12)” mean as it is shown in bitnodes.21.co?

I'm running a pruned full node of bitcoin core version 0.14.0 and checking on https://bitnodes.21.co/nodes/ I can see that my node was labelled "NODE_WITNESS (12)" unlike of the others nodes shown, ...
4
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1answer
177 views

How do you tell if witness data has been tampered with?

If you receive a block, how can you tell whether the witness data has been tampered with between when it was mined and when you received it? Where in the block is the wtxid root, and how do you ...
4
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1answer
154 views

Does segregated witness allow to securely create LN channel opening transactions?

In Rusty Russell's paper about the simplified version of the Lightning Network, some problems about the practical implementation of the opening channel method from the original LN paper are mentioned: ...
4
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1answer
871 views

Does the bitcoin testnet3 network support Segwit and OP_CSV?

As far as I know, Segregated Witness and OP_CHECKSEQUENCEVERIFY are the last features needed to be able to fully implement a trustless bi-directional payment channel, from start to finish. (...
4
votes
1answer
414 views

What is the status of the “Hong Kong Agreement”

Are the bullet points below still valid? We understand that SegWit continues to be developed actively as a soft-fork and is likely to proceed towards release over the next two months, as originally ...
4
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2answers
364 views

How segwit blocks are seen by segwit and non-segwit nodes?

Let's say a miner mines a block. In this block some transactions will be non-segwit and some will be segwit? The block contains two parts: The part with transactions The segregated part with ...
4
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6answers
390 views

Is the SegWit2X success due to concentration of mining power?

SegWit2X has been called a short-sighted & severely lacking proposal. There is nearly universal preference for its alternative among those listed on the segwit support overview (SegWit, BIP 141,...
4
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1answer
1k views

Redeem script for segwit addresses

How does one derive the Redeem Script for the new Pay-to-Witness Pubkey Hash addresses? With existing P2SH it's revealed after providing N number of Public Keys through a createmultisig function in ...
4
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1answer
236 views

If a block contains no SegWit transactions, does a miner send an (empty) witness?

Also, would that block's Coinbase contain some kind of empty witness commitment?
4
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1answer
220 views

Activation of SegWit v1

The segregated witness soft fork of August 2017 included a versioning field which would allow for future incrementation. Anthony Towns has recently posted an early draft of the proposal for the SegWit ...
4
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1answer
235 views

What library or wallet can be used to test segwit transactions on testnet?

Is there any code snippets / wallets to send segwit transactions on the testnet at the moment? I'm more looking for a code snippet or any library to support this to do some tests and make them ...
4
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0answers
706 views

To sign raw transaction in Segwit

I am using Bitcoin core 0.14.1 testnet. I created a Segwit address. transfer some coins to this address. Now I want to spend it. I created a raw transaction using console command i.e. ...
3
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4answers
2k views

Vanity address generation for Segwit?

Vanity address generation is currently strightforward for "old" Bitcoin addresses (starting with 1) with multiple software options available (oclvanitygen e.t.c). Is there any options to generate ...
3
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2answers
278 views

Can there be a half segwit, half normal Bitcoin transaction?

I was wondering if it's feasible to compile a bitcoin transaction that is somewhere in between (segwit and non-segwit), maybe one of these scenarios. I'll call the non-segwit inputs, normal inputs ...
3
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1answer
83 views

Can a coinbase transaction have a segwit output?

And more generally speaking, are there any restrictions on the output of a coinbase transaction?

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