To: Gregory Maxwell <greg@xiph.org>,
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
References: <d43c6082-1b2c-c95b-5144-99ad0021ea6c@mattcorallo.com>
	<CAAS2fgRF-MhOvpFY6c_qAPzNMo3GQ28RExdSbOV6Q6Oy2iWn1A@mail.gmail.com>
From: Matt Corallo <lf-lists@mattcorallo.com>
Message-ID: <22d375c7-a032-8691-98dc-0e6ee87a4b08@mattcorallo.com>
Date: Thu, 17 May 2018 12:59:22 -0400
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Subject: Re: [bitcoin-dev] BIP 158 Flexibility and Filter Size
Precedence: list

Yea I generally would really prefer something like that but it
significantly complicates the download logic - currently clients can
easily cross-check a filter in case they differ between providers by
downloading the block. If we instead went with the script being spent
they would have to be provided all previous transactions (potentially
compressed via midstate) as well, making it potentially infeasible to
identify the offending node while remaining a lightweight client. Maybe
there is some other reasonable download logic to replace it with, however.

Matt

On 05/17/18 12:36, Gregory Maxwell wrote:
> On Thu, May 17, 2018 at 3:25 PM, Matt Corallo via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> I believe (1) could be skipped entirely - there is almost no reason why
>> you'd not be able to filter for, eg, the set of output scripts in a
>> transaction you know about
> 
> I think this is convincing for the txids themselves.
> 
> What about also making input prevouts filter based on the scriptpubkey
> being _spent_?  Layering wise in the processing it's a bit ugly, but
> if you validated the block you have the data needed.
> 
> This would eliminate the multiple data type mixing entirely.
>