From: Peter Todd <pete@petertodd•org>
To: Jeremy <jlrubin@mit•edu>
Cc: Bitcoin Protocol Discussion
<bitcoin-dev@lists•linuxfoundation.org>,
"lightning-dev@lists•linuxfoundation.org"
<lightning-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] [Lightning-dev] OP_CAT was Re: Continuing the discussion about noinput / anyprevout
Date: Sat, 5 Oct 2019 11:49:02 -0400 [thread overview]
Message-ID: <20191005154902.ck236q65xha25ore@petertodd.org> (raw)
In-Reply-To: <CAD5xwhhLd9Ufv50kOi+yaJ5dTX9LhB1dPsK_0bqjz038tChcjw@mail.gmail.com>
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On Fri, Oct 04, 2019 at 11:40:53AM -0700, Jeremy wrote:
> Interesting point.
>
> The script is under your control, so you should be able to ensure that you
> are always using a correctly constructed midstate, e.g., something like:
>
> scriptPubKey: <-1> OP_SHA256STREAM DEPTH OP_SHA256STREAM <-2>
> OP_SHA256STREAM
> <hash> OP_EQUALVERIFY
>
> would hash all the elements on the stack and compare to a known hash.
> How is that sort of thing weak to midstateattacks?
Obviously with care you can get the computation right. But at that point what's
the actual advantage over OP_CAT?
We're limited by the size of the script anyway; if the OP_CAT output size limit
is comparable to that for almost anything you could use SHA256STREAM on you
could just as easily use OP_CAT, followed by a single OP_SHA256.
--
https://petertodd.org 'peter'[:-1]@petertodd.org
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next prev parent reply other threads:[~2019-10-05 15:49 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-30 13:23 [bitcoin-dev] " Christian Decker
2019-09-30 16:00 ` ZmnSCPxj
2019-09-30 23:28 ` ZmnSCPxj
2019-10-01 14:26 ` Christian Decker
2019-10-01 14:45 ` Anthony Towns
2019-10-01 15:42 ` ZmnSCPxj
2019-10-01 14:20 ` Christian Decker
2019-10-01 15:35 ` ZmnSCPxj
2019-10-03 9:42 ` Christian Decker
2019-10-01 12:23 ` Chris Stewart
2019-10-01 13:31 ` [bitcoin-dev] [Lightning-dev] " ZmnSCPxj
2019-10-03 10:01 ` Christian Decker
2019-10-03 9:57 ` Christian Decker
[not found] ` <CACJVCgJ9PL-2jTS71--tXsa=QkK+f5_ciYLwv468WUno=XXAig@mail.gmail.com>
2019-10-01 14:27 ` Ethan Heilman
2019-10-01 15:14 ` Chris Stewart
2019-10-03 10:30 ` Christian Decker
2019-10-01 15:59 ` [bitcoin-dev] " Anthony Towns
2019-10-02 2:03 ` ZmnSCPxj
2019-10-03 1:47 ` [bitcoin-dev] [Lightning-dev] " Anthony Towns
2019-10-03 3:07 ` ZmnSCPxj
2019-10-03 15:05 ` [bitcoin-dev] OP_CAT was " Ethan Heilman
2019-10-03 23:42 ` [bitcoin-dev] [Lightning-dev] " ZmnSCPxj
2019-10-04 0:48 ` Ethan Heilman
2019-10-04 5:02 ` Jeremy
2019-10-04 7:00 ` ZmnSCPxj
2019-10-04 18:33 ` Jeremy
2019-10-04 11:15 ` Peter Todd
2019-10-04 18:40 ` Jeremy
2019-10-05 15:49 ` Peter Todd [this message]
2019-10-06 8:46 ` ZmnSCPxj
2019-10-06 9:12 ` Peter Todd
2019-10-06 7:02 ` Lloyd Fournier
2019-10-09 16:56 ` Andrew Poelstra
2019-10-02 15:11 ` [bitcoin-dev] " s7r
2019-10-03 11:08 ` Christian Decker
2019-10-05 10:06 ` Anthony Towns
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