8
votes
Accepted
Why are hashSequence and hashPrevouts computed separately?
The reason is increasing the ability to precompute and/or cache those hash values once for the whole transaction (potentially allowing them to be used for many signatures).
In "normal" (...
- 108k
7
votes
What are the risks of running a pre-SegWit node (0.12.1)?
In addition to Michael's excellent answer, Bitcoin Core v12.1 doesn't include many performance improvements added over the years. Block verification is about twice as slow compared to v25.0 (according ...
- 9,364
6
votes
Accepted
What would happen if we provide witness program different than 32 bytes for SegWit 1?
SegWit version 1 outputs with lengths other than 32 bytes remain unencumbered, which means their validation is unchanged and they remain anyone-can-spend. From BIP341:
A Taproot output is a native ...
- 9,364
6
votes
Accepted
What are the risks of running a pre-SegWit node (0.12.1)?
Is it safe to assume that Bitcoin is not soft-fork backward compatible?
The only benefit of a soft fork over say a hard fork is that old nodes aren't forked off the network if they fail to validate ...
- 15.7k
6
votes
What are the risks of running a pre-SegWit node (0.12.1)?
Pre-segwit nodes consider segwit transactions non-standard and will not accept them to their mempool and therefore also not forward them. They would only participate in relay of unconfirmed non-segwit ...
- 76.9k
5
votes
Accepted
Are all transactions, whether SegWit or non-SegWit, part of the commitment in a coinbase transaction?
The wtxids of all transactions are committed to by the witness commitment tree in the coinbase transaction (except the coinbase wtxid itself, as that would be a cyclic dependency). This includes non-...
- 108k
4
votes
Accepted
Is a BIP required for the removal of SegWit Discount for Inscriptions?
The removal of the witness discount would be a consensus change, specifically a soft fork. Changes to consensus rules have always been standardized as BIPs ever since the BIP process was created and I ...
- 9,364
4
votes
Why are some bc1 addresses 42 characters and others 62 characters in Base58?
P2WPKH (pay-to-witness-public-key-hash) addresses are 42 characters in length and P2WSH (pay-to-witness-script-hash) addresses are 62 characters in length (see here). bc1 addresses also use bech32 ...
- 15.7k
4
votes
How could a 2 byte witness program make sense?
Gregory Sanders proposed Segwit Ephemeral anchors, in which a 2-bytes witness program in a transaction's output to make it opt in to different relay rules (BIP, Optech).
- 8,911
4
votes
Accepted
Is it possible to "label" Segwit spendable output ScriptPubKeys with arbitrary bytes?
Would it be valid; spendable by a Segwit transaction?
It is valid to create such an output, but it would not be considered a segwit output (see BIP141), and thus not spendable using a segwit input.
...
- 108k
3
votes
Accepted
How do pre-Segwit nodes interpret transactions containing Taproot OP_CHECKSIGADD?
Tapscript can only appear in leaf scripts. Leaf scripts can only appear in the witness stack of a P2TR script path spend. Pre-segwit nodes don’t see witness data. Ergo, a pre-segwit node will never ...
- 76.9k
3
votes
Accepted
What is the default private key type for legacy and segwit addresses?
The term "compressed private key" is a misnomer; it's not the private key that is compressed. Instead, it is an indication about whether the corresponding public key is to be in compressed (...
- 108k
3
votes
SegWit Version - is there a proposal for new versions?
Taproot is implemented as SegWit version 1.
Another proposed feature that would most likely be implemented as a new SegWit version is cross-input signature aggregation.
- 9,364
3
votes
Accepted
How are the block header bytes treated when calculating the block size in weight?
Are these header bytes treated as non-segwit bytes, i.e. cost 4 WU, so we actually have 3,999,668 WU (4,000,000 - 320 WU for header - 12 WU for tx counter) for transactions?
Yes. The header weighs ...
- 108k
3
votes
Accepted
What happens when we send MSG_WITNESS_TX/MSG_WITNESS_BLOCK to non-segWit node?
That would be a violation of BIP144.
Support for segwit is signalled by having NODE_WITNESS in the services advertized in the version packet. If a peer does not signal NODE_WITNESS, it cannot be sent ...
- 108k
3
votes
Accidently sent BTC to taproot wallet on Phantom. Wondering how i can get it back to Segwit so i can buy ordinals with it
Note that addresses are not accounts.
The only way to move your coins to a different address (regardless of type) is to make a transaction. Presumably the wallet you are using allows you to send ...
- 71.5k
3
votes
Accepted
Did Segwit (BIP141) eliminate all txid malleability issues listed in BIP62?
Most of the malleability issues listed in BIP62 stem from the fact that an input script (scriptSig) can be modified and still remain valid for the input, and because the input script is included when ...
- 9,364
2
votes
What is arbitrary witness data and unspent transaction output?
What is arbitrary witness data and unspent transaction output? [...] I'm confused what they mean by UTXO
Arbitrary
Arbitrary means what you think it does - "the data can be anything you choose&...
- 28k
2
votes
Accepted
Can a non-segwit transaction be serialized in the segwit format?
The extended serialization format introduced in BIP144, which is used for serializing witnesses, specifies:
If the witness is empty, the old serialization format must be used.
So, no, using the ...
- 108k
2
votes
Accepted
the purpose of the field before signature in P2WPKH
It is the number of witness items in the witness stack of input #0 of the transaction.
See BIP144 for the serialization format used by segwit transactions:
the only witness objects type supported are ...
- 108k
2
votes
Accepted
Which private key is used in Taproot transactions?
In a key path spend, you always sign with the private key corresponding to the output key. If that key is a tweaked public key (it's recommended to always use a tweaked key), you will also need to ...
- 9,364
2
votes
Accepted
Are there plans to make a script invalid if there is more than one element left in the stack?
This is a consensus rule inside (P2SH-)P2WSH witness scripts, and P2TR script-path spends already.
See BIP141:
The script must not fail, and result in exactly a single TRUE on the stack.
And BIP342:
...
- 108k
2
votes
How do pre-Segwit nodes interpret transactions containing Taproot OP_CHECKSIGADD?
OP_CHECKSIGADD is only defined for SegWit v1 (Taproot). A pre SegWit v1 node that doesn't recognize Taproot rules will treat all SegWit v1 outputs as "anyone can spend" regardless of whether ...
- 15.7k
2
votes
Accepted
Exact witness requirements for a segwit transaction with P2PKH and P2WPKH inputs
From the BIP141 specification:
The witness is a serialization of all witness fields of the
transaction. Each txin is associated with a witness field. A witness
field starts with a var_int to indicate ...
- 958
2
votes
Accepted
Why can I not find my transaction in the mempool?
This transaction appears to not be eligible for confirmation because it spends inputs that do not exist.
You write that you are using testnet, but neither of the two transactions 21f5…a273 and 2275…...
- 76.9k
2
votes
Accepted
marker byte interpretation by legacy transaction parser
Legacy transaction parsers do not consider segwit transactions to be valid. They will fail to parse the transaction when read the marker byte as indicating 0 inputs.
Part of the way that segwit ...
- 71.5k
2
votes
Is Testnet3 Addresses Support Segwit P2WSH P2WPKH transactions?
It's Pay to Public Key Hash(P2PKH) testnet address, which doesn't support SegWit.
P2PKH address(legacy) which starts with “1”, starts with either "m" or "n" on testnet.
You can ...
- 425
1
vote
Accepted
Transaction Validation
Any input spending a non-segwit script type must not have a witness. If it does, the transaction is invalid.
P2SH-P2WSH and P2SH-P2WPKH are the exceptions: if the script type is P2SH and the ...
- 71.5k
1
vote
Accepted
Example of computing segwit txid from raw tx data
what bytes exactly should be removed
Those corresponding to the Segwit data fields:
segwit flag and marker after the version number (bytes 4-5 with zero-based indexing).
segwit witness data between ...
- 28k
1
vote
Creating a raw Segwit transaction from scratch and getting Signature must be zero for failed CHECK(MULTI)SIG operation
OK, finally I got some things to work and there are quite some changes I had to make but it seems to have work.
I need to retrace my steps all over again later on tomorrow as its late now.
Here's the ...
- 207
Only top scored, non community-wiki answers of a minimum length are eligible