From: Johnson Lau <jl2012@xbt.hk>
To: Praveen Baratam <praveen.baratam@gmail.com>,
bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Why SegWit Anyway?
Date: Tue, 21 Nov 2017 01:45:18 +0800 [thread overview]
Message-ID: <F392E62C-00CF-4D91-BB6B-706F2A59C63B@xbt.hk> (raw)
In-Reply-To: <CAAQs3wuDPktHc6kiZXqTaatOheX4KP=TRgje0_-ED5h8iNs-MA@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1643 bytes --]
We can’t “just compute the Transaction ID the same way the hash for signing the transaction is computed” because with different SIGHASH flags, there are 6 (actually 256) ways to hash a transaction.
Also, changing the definition of TxID is a hardfork change, i.e. everyone are required to upgrade or a chain split will happen.
It is possible to use “normalised TxID” (BIP140) to fix malleability issue. As a softfork, BIP140 doesn’t change the definition of TxID. Instead, the normalised txid (i.e. txid with scriptSig removed) is used when making signature. Comparing with segwit (BIP141), BIP140 does not have the side-effect of block size increase, and doesn’t provide any incentive to control the size of UTXO set. Also, BIP140 makes the UTXO set permanently bigger, as the database needs to store both txid and normalised txid
> On 21 Nov 2017, at 1:24 AM, Praveen Baratam via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> Bitcoin Noob here. Please forgive my ignorance.
>
> From what I understand, in SegWit, the transaction needs to be serialized into a data structure that is different from the current one where signatures are separated from the rest of the transaction data.
>
> Why change the format at all? Why cant we just compute the Transaction ID the same way the hash for signing the transaction is computed?
>
> --
> Dr. Praveen Baratam
>
> about.me <http://about.me/praveen.baratam>_______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
[-- Attachment #2: Type: text/html, Size: 3379 bytes --]
next prev parent reply other threads:[~2017-11-20 17:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-20 17:24 [bitcoin-dev] Why SegWit Anyway? Praveen Baratam
2017-11-20 17:39 ` Ariel Lorenzo-Luaces
2017-11-20 17:45 ` Johnson Lau [this message]
[not found] ` <CAAUFj10ZRQrtEzB_2wp-WS8Q-FGcSegpc_Z6kqvqnDLzNn=DrA@mail.gmail.com>
[not found] ` <CAAUFj11_Vh2K4MrmuBre5KaX6F16Jg3PYAsj6SSfzoYYRz_WyA@mail.gmail.com>
2017-11-20 18:04 ` Dan Bryant
2017-11-21 13:10 ` Steve Shadders
2017-11-21 13:16 ` Adán Sánchez de Pedro Crespo
2017-11-25 15:41 ` CANNON
2017-11-20 18:07 ` Praveen Baratam
2017-11-20 19:58 ` Johnson Lau
2017-11-20 18:59 ` Gregory Maxwell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=F392E62C-00CF-4D91-BB6B-706F2A59C63B@xbt.hk \
--to=jl2012@xbt.hk \
--cc=bitcoin-dev@lists.linuxfoundation.org \
--cc=praveen.baratam@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox