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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138 views

Parsing a SegWit transaction, what are stack items in witness data

For every input we can have multiple stack items, what do these represent? As a reference this question is helpful Are these defined here? For eg. P2WPKH would have a signature followed by a pubkey, (...
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2answers
342 views

Can BIP91 cause a chain split?

BIP91 forces BIP141 signaling, the blocks that do not signal BIP141 will be rejected by those who are pro-BIP91. The minority of miners that do not support BIP91 (and by extension BIP141), could start ...
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2answers
273 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 ...
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1answer
436 views

BIP91 Activation Period

I understand that BIP91 needs 269/336 signaled blocks. My question is is it a rolling window of any 336 blocks or are there activation periods of 336 blocks that start and end at predetermined block ...
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3answers
423 views

When is the earliest we will see SegWit transactions on main net

I am assuming that only after SegWit activation SegWit txs will be on mainnet, what i cannot determine is the date for that event. Can anyone help? So far i have seen references to late August.
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144 views

How to track UASF support?

It's easy to see that currently 50% of the hashrate supports Segwit. It's also simple to find that about 1000 nodes are supporting it. But I can't seem to figure out how significant that amount is, ...
2
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1answer
75 views

What is the difference between mauling and transaction malleability?

http://stevengoldfeder.com/papers/ZKCSP.pdf notes: The protocol presented in [5] is vulnerable to the so-called mauling problem, where an adversary which knows the hash identifier T of a ...
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1answer
347 views

Why is there so much uncertainty with SegWit2x when it has 85%+ mining support?

I'm confused about the uncertainty and pessimism about the Bitcoin scaling debate. I see coindance https://coin.dance/blocks is signalling a 85% support for SegWit2x. As far as I know SegWit kills 2 ...
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1answer
2k views

How does Segwit prevent ASICBOOST?

I know that ASIC BOOST exploits the fact that the blockheaders are not a multiple of 64 bytes, but what is the change in Segwit that prevents this? Are they always a multiple of 64 bytes now for ...
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2answers
1k 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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1answer
81 views

Do sigops count towards the block weight in SegWit?

I was just rereading the SegWit benefits page and noticed that the section Moving towards a single combined block limit contains an example in which sigops count towards the blockweight. Did this ...
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1answer
354 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?
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2answers
674 views

SegWit witness commitment merkle root location

BIP 141 defines the commitment structure here What i am unsure about is the location of this data. I know it will be in scriptPubKey. Does this mean Coinbase tx will have more than one output? Also is ...
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1answer
553 views

Parsing a SegWit transaction - what is the size of witness data?

I'm parsing s SegWit transaction, I got it done until i reach the witness data. How big is the witness data?
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1answer
70 views

Which BIP-148 branch is the most recommended?

I want to run an BIP-148 ("segwit UASF") node. However, I am not sure which of the various branches is most maintained and recommended to run. There is this pull request by earonesty (386 commits ...
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1answer
177 views

What are the positives and negatives of “Flexible transactions”?

What are the positives and negatives of Bitcoin Classic's Flexible Transactions? (related BIP 134) Why aren't they used instead of Segwit? It seems that they solve the exact same issues as Segwit, in ...
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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,...
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1answer
145 views

Blocks, scaling and segwit question

Somewhat new to bitcoin, trying to understand the tech... For my understanding all the transactions go into a block, every 10 minutes the block is mined and all transactions in it are confirmed. With ...
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1answer
651 views

After Segwit Activation, what is the largest block size possible?

The code says MAX_BLOCK_SERIALIZED_SIZE = 4000000, but that is actually not a actually consensus rule as stated here: https://github.com/bitcoin/bitcoin/issues/10289 The actual consensus rule is ...
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1answer
281 views

Segwit: Arbitrary data storage in witness?

Let's say I want to encode the text of the King James version of the Bible into the block chain, one piece at a time (replace this with any zany idea to consume copious quantities of block space). ...
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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). ...
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2answers
133 views

What is the weight of a block that contains no pay-to-witness scripts?

I'm trying to understand block weight, a metric introduced by segwit (BIP-141): block weight = 3 * base size + total size "base size" is the length of a pre-segwit block, which contains only ...
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1answer
241 views

Why is BIP-147 (Dealing with dummy stack element malleability, part of segwit) necessary?

Given BIP-11 (M-of-N Standard Transactions) it's not clear why BIP-147 (Dealing with dummy stack element malleability) is necessary. BIP-11 states: OP_CHECKMULTISIG transactions are redeemed using ...
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1answer
177 views

What is impact of the possible nitwit fork on August 1? Will it double the coins I have?

If the Nitwit proposal is activated at the end of July then as I understand a hard fork will occur because miners and nodes that continue using the old software will generate blocks in the old format, ...
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0answers
161 views

What is UASF, BIP148, Segwit, Segwit2x? [duplicate]

I keep reading these terms and I don't follow this everyday. Last I heard was that segwit was suppose to solve the block size debate. What are all these new terms like segwit2x and UASF?
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1answer
13k views

How is segwit2x different from segwit?

Today everybody got the news about the potential segwit2x adoption. However, I am trying to understand: while both of them based on the same segwit principals how they are different? Is it about the ...
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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> ...
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1answer
250 views

What happens to bitcoin when Segwit2MB activates?

Specifically what will happen with bitcoin in wallets. Do I have to try and quickly buy "Segwit coins" if the value of bitcoin core drops? Do I have equal amounts of Segwit and core coins? If so ...
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1answer
669 views

Transaction verification by miner VS full node with & without SegWit

I'm trying to fill a few gaps in my understanding of transaction verification and would appreciate any insight. Without SegWit Miners broadcast new blocks which contain the signature(s) with every ...
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1answer
2k views

What will happen on November 15th 2017, when the Segwit proposal expires?

The time duration for the BIP-148 UASF is from August 1st to November 15th. During this time, the BIP-148 nodes will reject blocks that do not signal for Segwit. Now, after Nov. 15th, even the BIP-...
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1answer
514 views

Litecoin has had SegWit for one month, what impact did that have?

Litecoin activated SegWit about one month ago on May 10th (block 1201536). What impact did the SegWit activation on Litecoin have? How many blocks have a witness commitment? How many SegWit ...
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1answer
239 views

How do we “exchange coins on one blockchain for those on the other”?

With Segwit and BIP-148 coming, I have been trying to figure out what's exactly gonna happen with Bitcoin after August 1, by watching videos and reading articles. One thing (among many others) ...
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1answer
459 views

What is the “witness reserved value” for BIP-141?

BIP-141 defines a witness reserved value as part of a flexible commitment structure: Double-SHA256(witness root hash|witness reserved value) The purpose is to support commitments (i.e., data ...
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2answers
221 views

Which kinds of transactions show quadratic signature-hashing scaling?

It has been stated: A major problem with simple approaches to increasing the Bitcoin blocksize is that for certain transactions, signature-hashing scales quadratically rather than linearly. https:/...
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0answers
53 views

What does the SegWit2MB proposal agreed upon at Consensus 2017 entail for the bitcoin network?

From what I've read, I know this proposal is the combination of a hardfork to 2MB blocks with the activation of SegWit, but I haven't actually seen the code for this proposal to understand what the ...
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1answer
84 views

Once SegWit is implemented, could updated miners still choose to ignore SegWit transactions?

Regular transactions can be ignored. What about SegWit transactions?
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53 views

What is segregated witness? [duplicate]

I have heard increased talk of an idea known as "segwit" or segregated witness. Quite simply, what is "segwit", why are people discussing it now and what are its main implications?
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1answer
63 views

How does BIP9 handle expiration dates over retargeting periods?

Suppose a BIP9 feature is set to expire on day T. Suppose further that the retargeting period before T actually ends on day T+5, but the retargeting period (2016 blocks) actually signals for the BIP9 ...
2
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1answer
234 views

Incentives for Segwit vs BTU

I had the (appearntly wrong) impression that miners as a whole would prefer limiting the block size / scalability / TPS in order to increase fees (basically limiting the supply), and users and ...
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1answer
133 views

Is SegWit a step in the direction toward implementing pegged sidechains into Bitcoin?

Is Segregated Witness a step in the direction toward implementing pegged sidechains into Bitcoin?
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2answers
142 views

Technical problems in deployment of segwit parallely on bit 4

Recently(as of May 24, 2017) segwit2mb HF has been proposed. A core developer has reported that another deployment of segwit via bip 109 on bit 4 would require code duplication. Although the above ...
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1answer
310 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
710 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 ...
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2answers
166 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 ...
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1answer
316 views

How would segwit help bitcoin services like, blockstream profit, and miners to loose?

Segwit in the current form, How would it affect miners except, asicboost? How would blockstream (other than miners) kind of companies benefit from it, in such a way that miners can't? I'm looking ...
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0answers
351 views

Why does segwit save space on the blockchain?

I've had a hard time finding a good source online that explains segwit. I've read the basic idea is to store the scriptSigs separately as the scriptSig is potentially malleable, and then compute the ...
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229 views

How to make Simplecoin's powerpool to support Litecoin Segwit?

I tweek the code transation.py https://github.com/simplecrypto/cryptokit/blob/master/cryptokit/transaction.py#L150 add: if (self.default_witness_commitment is not None): data += b'\x00' ...
2
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1answer
333 views

How does a non-upgraded node read a SegWit transaction? [duplicate]

I'm trying to understand how my node would interperet a SegWit transaction if I do not upgrade. Even if I do not upgrade, I should be ...
3
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1answer
398 views

Does Segwit mean easier government monitoring?

I have noticed a steady stream of PR articles talking ad nauseum of the dangers of a contentious hard fork and how miners refusing to signal segwit are screwing us all. Many are quite well written and ...
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1answer
981 views

Can I get the wallet in bitcoind to use P2SH segwit (on testnet)?

Can I use the wallet functionality in bitcoin cli daemon with P2SH segwit on testnet/regtest? Meaning, can I receive on these addresses and send from them? And if I can, how? I cannot find it ...