public inbox for bitcoindev@googlegroups.com
 help / color / mirror / Atom feed
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>

[-- Attachment #1: Type: text/plain, Size: 882 bytes --]

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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

  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] Continuing the discussion about noinput / anyprevout 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

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=20191005154902.ck236q65xha25ore@petertodd.org \
    --to=pete@petertodd.org \
    --cc=bitcoin-dev@lists.linuxfoundation.org \
    --cc=jlrubin@mit.edu \
    --cc=lightning-dev@lists.linuxfoundation.org \
    /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