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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How to sign a SegWit transaction via NBitcoin?

Most tutorials out there just show how to sign it in the legacy way. And I know that NBitcoin already supports SegWit, so is there a snippet out there on how to sign it this way?
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1answer
3k views

Segwit to legacy address transaction possible?

If I have a segwit address and I want to send BTC to the exchange, which supports only legacy addresses, can I even tranfer the money?
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1answer
353 views

BIP91 is activated, why BIP141 is still dormant?

The moment is BIP91 activated non-SegWit signaling blocks will be orphaned. Since BIP91 is now activated won't that immediately boost BIP9 to 100%? Why is it not happening?
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3answers
424 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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2answers
236 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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1answer
652 views

OP_RETURN in a coinbase transaction?

Hey looking at this transaction I'm confused why there are two outputs and why one of them is labelled with OP_RETURN
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1answer
114 views

Why does P2SH-P2WPKH use DER encoded signatures?

If we simply assumed 32 bytes of r and s each, then signatures can be 64 bytes. Now they are on average 71 bytes in DER plus an additional byte to declare their size, effectively making them use 72 ...
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1answer
707 views

SegWit address to Non-SegWit addresses

If I send from a segwit wallet to a non segwit wallet, does the tx not show up in the other wallet until there is a confirmation?
2
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1answer
179 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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1answer
381 views

How to compute double sha256 shown in examples of bip 143?

How do I compute the double sha256 shown in example of bip 143? The example in Native P2WPKH hashPrevouts: dSHA256(...
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1answer
47 views

Parsing stripped-witness blocks

I've read all the relevant BIPs, and am still confused. Are segwit enabled blocks stripped of witness data and marker and flag bytes when they are propagated to non-segwit peers? Or are they just ...
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1answer
53 views

Why is a library's signature of a segwit tx different from Bitcoin Core signature?

I have been writing a (yet another) Bitcoin python library primarily for educational purposes; for me and my students. Signing a non-segwit transaction results in a signed tx that is identical to ...
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1answer
196 views

What does it mean if TXID and WTXID are the same?

I'm having a tough time understanding what exactly WTXID is and what it means when WTXID and TXID are the same (and vica versa). What I understand is that WTXID includes the witness data. Since non-...
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2answers
133 views

Do legacy nodes receive the witness fields of a Segwit transactions?

My question comes from not understanding how BIP 144 works? Regarding the BIP what I ask is, whether legacy nodes support the new parser, so that they treat Segwit tranasctions as valid? There it is ...
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1answer
158 views

Extract lightning network funding transactions with python bitcoin blockchain parser lib

My ultimate goal is to parse funding transactions (as well as channel closes in a later step) from the blockchain. In order to do so I wanted to start with a funding transaction and disect it. ...
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2answers
1k views

Why is my segwit private key generating a 3 address vs a bc1 address like how I originally generated?

I have the following btc private key that I generated from another application: 5KCPzu4tEAnFqwLrXUbW3GKMDSnUYY8CMie2HMRuHouSvrFhXA9 That application gives me the following segwit address: ...
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1answer
382 views

Creating a new electrum 3 wallet file with an imported segwit private key

I have a segwit private key that I generated from another app. How can I create a new electrum wallet file with just this private key in there? I tried creating a new electrum 3 wallet with this ...
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1answer
122 views

Bitcoin Core - When is fAllowWitness evaluated to true?

In Bitcoin Core, when is fAllowWitness evaluated to true? transaction.h const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS); In particular, I cant figure out the ...
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1answer
271 views

Legacy blockchain after upgrade to SegWit

Let's suppose I run a legacy (non-SegWit) node after SegWit gets activated. My blockchain doesn't store any SegWit data. What happens when I upgrade my node? Will I have to re-download the blockchain ...
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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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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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1answer
68 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 ...
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1answer
235 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
842 views

Is there an address format for P2WPKH or P2WSH?

Is there an address format for P2WPKH or P2WSH? If P2WPKH uses the same address format as P2PKH, how does a wallet know which one to use?
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1answer
53 views

Why does witness use count instead of length?

In legacy transaction (without SegWit) the scriptSig is easily parsed by knowing the length of it (a CompactInt value) and without needing to read the script in place. However in SegWit transaction ...
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1answer
49 views

Does my segwit node only have segwit blocks?

My segwit node makes a gettxout RPC query and checks the scriptPubKey.type is "witness_v0_keyhash" and does things accordingly. To my understanding old nodes have different blocks and if I happened ...
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1answer
177 views

How to set custom segwit change address in v0.15 Core via config

We generated segwit addressess via addwitnessaddress command in v0.15 core client. Therefore receiving funds to our segwit addresses. When spending those segwit UTXO, wallet creates a standard change ...
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1answer
168 views

Who witnesses a Segregated Witness transaction and what incentive do they have to witness the extended block containing signatures?

This video claims Segregated Witness is insecure because no one has an incentive to process (witness) the extended signature block. https://www.youtube.com/watch?v=VoFb3mcxluY It claims that as the ...
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1answer
78 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
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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2answers
143 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
1k views

Using segwit and creating Pay-To-Witness (P2WPKH) addresses

I'm going through this guide: https://bitcoincore.org/en/segwit_wallet_dev/ I might be understanding this incorrectly, but it sounds like the users and/or wallet custodian (coinbase, blockchain.info, ...
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1answer
167 views

What's the segwit transaction serialization “flag” field for?

According to bip 141, the segwit transaction serialization format (used to compute the wtxid) is: [nVersion][marker][flag][txins][txouts][witness][nLockTime] The bip mentions that the flag field ...
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1answer
71 views

Why is the wtxid considered malleable?

Why is the wtxid considered malleable since the transaction is unconfirmed? How can a third-party modify it?
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1answer
448 views

How can a third party spend BCH accidentally sent to a BTC address?

I transferred BCH to an Electrum wallet address and haven't ever received it because Electrum uses only BTC. As I have been trying to recover it, I looked up the transaction on explorer.bitcoin.com ...
2
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1answer
279 views

Derive the bech32 address from the transaction 'txinwitness' witness data in Bitcoin Core 0.16

I'm trying to extract the bech32 address associated to an input or output using the txinwitness field included in every pure SegWit transaction. An example with transaction ...
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2answers
67 views

Do lightweight wallets validate signatures? If not, why?

I've learned that "some SPV clients simply don’t check signatures themselves at all": https://bitcoincore.org/en/2016/01/26/segwit-benefits/#efficiency-gains-when-not-verifying-signatures I wonder if ...
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2answers
1k views

Bitcoin - Technical difference between P2PKH and P2SH address generation?

I was convinced that the only difference between the generation of addresses starting with '1' and '3' was simply changing the prefix added to the digest from 0x00 to 0x05 after the ripemd160 part. ...
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1answer
143 views

How does a non-segwit full node ensure validation of the blockchain?

Let's say a block been created with most tx are segwit , now the block is more then 1MB and will be near to 4MB, I understand that a non-SegWit node ( let's say bitcoin-core 0.15 ) cannot get a block ...
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2answers
612 views

what is the explanation of “witness version” and its usage?

What is the witness version and how is it used? A segwit transaction is comprised of: [nVersion][marker][flag][txins][txouts][witness][nLockTime] From the BIP: "A witness field starts with a var_int ...
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1answer
1k views

What Do SegWit Addresses Look Like?

Probably a question that has been asked a lot before, but how do I know if an address I generate with bitcoind and bitcoin-cli is SegWit? I take the following steps to (attempt to) generate a SegWit ...
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1answer
396 views

Generate Bech32 addresses to receive customer funds

I would like to use Segwit addresses however I seem to be finding mixed information on compatibility. As I currently understand it, older clients will not be able to send to a Bech32 address. Is this ...
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1answer
212 views

Where does the extended block in a segwit transaction get stored?

I understand where normal blocks get stored. They’re passed along and saved by various nodes. What about the extended blocks of a segwit transaction.
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1answer
569 views

How to properly backup a address with private key after 'addwitnessaddress' command

I've received my balance to my addresss that starts with 3 which is after 'addwitnessaddress' command. I'd like to know that how do I properly backup my balance to keep safety. Bitcoin Core has a ...
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1answer
155 views

Would fees go down once more people start using segwit addresses for day to day activity?

Since the fees are high today, when more wallets and people start using segwit (bc1) addresses. Would sending from legacy address fees go down as everyone is using the newer address? Or it doesnt ...
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1answer
602 views

What was the number of the block in which SegWit got activated? And first transaction?

It was definitely on August 24th 2017, but not sure about the block number. Many sources reference block 481,822; but others state 481,824. Also, even if this was the first block to allow segwit ...
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1answer
111 views

BIP9: What happens if I make a segwit transaction after lock in but before activation?

Will it be treated a anyone-can-spend or do the nodes enforce the new rules? Along the same lines, what exactly happens when we say a soft fork is activated? Are the enforced at the time SF becomes ...
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1answer
497 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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1answer
341 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 ...
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1answer
63 views

Can Segregated Witness function in an Emergent Consensus environment?

Same as subject. I've been finding it difficult to find any discussion on the current Emergent Consensus implementation and theory, but I have seen reservations. Does it adversely impact the ...

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