From: Peter Todd <pete@petertodd•org>
To: Ethan Heilman <eth3rs@gmail•com>
Cc: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] A proposal to reintroduce the disabled script opcodes
Date: Mon, 22 May 2017 12:14:04 -0400 [thread overview]
Message-ID: <20170522161404.GA18885@fedora-23-dvm> (raw)
In-Reply-To: <CAEM=y+XbHsCQ__u-oVqp8AjWoR29G45ZRDRDdFAMYJhqtRN0Pg@mail.gmail.com>
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On Mon, May 22, 2017 at 10:41:40AM -0400, Ethan Heilman wrote:
> >It'd help your case if you gave us some examples of such scripts being
> used.
>
> I want OP_CAT so that I can securely and compactly verify many hashes and
> hash preimages. This would shrink offchain Tumblebit transactions
> significantly.
>
> For instance if I want a transaction TxA which checks that a transaction
> TxB releases preimages x1,x2,...,x10 such that
> y1=H(x1), y2=H(x2),...,y10=H(x10). Currently I just put y1,...y10 and check
> that the preimahes hash correctly. With OP_CAT I would only have to store
> one hash in TxA, yhash
>
> ytotal = H(OP_CAT(H(OP_CAT(y1, y2)),y3)...y10)
>
> TxA could then just hash all the preimages supplied by TxB and confirm they
> hash to TxA. This would reduce the size of TxA from approx 10*32B to
> 32+10*16B. I have a version which improves this further but it is more
> complex.
>
> Most of the math OP codes aren't particularly helpful due to their 32bit
> nature and their strange overflow behavior.
Great! That's exactly the type of justifying use-case we need for a BIP.
An OP_CAT will have to have limits on maximum output size; how big an output
does your application need?
--
https://petertodd.org 'peter'[:-1]@petertodd.org
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next prev parent reply other threads:[~2017-05-22 16:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-19 6:07 Mark Boldyrev
2017-05-19 13:13 ` Hampus Sjöberg
2017-05-22 14:09 ` Peter Todd
2017-05-22 14:41 ` Ethan Heilman
2017-05-22 16:14 ` Peter Todd [this message]
2017-05-22 16:43 ` Ethan Heilman
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