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From: Achow101 <achow101-lists@achow101.com>
To: Pieter Wuille <pieter.wuille@gmail.com>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Witness serialization in PSBT non-witness UTXOs
Date: Mon, 13 Aug 2018 20:32:33 +0000	[thread overview]
Message-ID: <7A_00K2wcfdgZMimY9aZ4gUFWyVIPOVrnueAFAosM-S-gIIoHXez6v5GcC8OrfTULz0NZ6n1g3T9jfVbgBvU_jKbgmNd-zlVqQVOC00NphA=@achow101.com> (raw)
In-Reply-To: <CAPg+sBgf-qSh0UVZF5RZnO+nygF-HN9=LL1gxE1JfXKrQhBbmw@mail.gmail.com>

Hi,

Since the BIP is already in proposed status, I think that we should specify the non-witness utxo to just be "witness or non-witness" serialization. This maintains compatibility with things that have already implemented but also maintains the forwards compatibility that is needed.

Andrew


‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On August 13, 2018 11:56 AM, Pieter Wuille via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:

> Hello all,
>
> BIP174 currently specifies that non-witness UTXOs (the transactions
> being spent by non-witness inputs) should be serialized in network
> format.
>
> I believe there are two issues with this.
>
> 1.  Even in case the transaction whose output being spent itself has a
>     witness, this witness is immaterial to PSBT. It's only there to be
>     able to verify the txid commits to the output/amount being spent,
>     which can be done without witness.
>
> 2.  "Network format" is a bit ambiguous. We can imagine a future
>     softfork that introduces a new type of witness. Network format could
>     be interpreted as including that new witness type, which is clearly
>     unnecessary (by the above argument), and would gratuitously break
>     compatibility with existing signers if implemented pedantically.
>
>     So my suggestion is to update the specification to state that
>     non-witness UTXOs must be serialized without witness. If it's too late
>     for that, it should instead be updated to explicitly specify with or
>     witnout witness, but it's safe to drop the witness.
>
>     Opinions?
>
>     Cheers,
>
>     --
>     Pieter
>
>
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev




  reply	other threads:[~2018-08-13 20:32 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-13 18:56 [bitcoin-dev] Witness serialization in PSBT non-witness UTXOs Pieter Wuille
2018-08-13 20:32 ` Achow101 [this message]
2018-08-13 20:39   ` Gregory Maxwell

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