public inbox for bitcoindev@googlegroups.com
 help / color / mirror / Atom feed
From: Gregory Maxwell <gmaxwell@gmail.com>
To: Gavin Andresen <gavinandresen@gmail.com>
Cc: bitcoin-dev@lists.linuxfoundation.org
Subject: Re: [bitcoin-dev] For discussion: limit transaction size to mitigate CVE-2013-2292
Date: Mon, 20 Jul 2015 20:55:57 +0000	[thread overview]
Message-ID: <CAAS2fgRBa47ye-ouV2jDe16MJFCKxYh0zF0Jw4BTwzpXVKgwOg@mail.gmail.com> (raw)
In-Reply-To: <CABsx9T30aUx+Leb2HXx2QrMT8R_eTXV9hiC99av957645iQm1Q@mail.gmail.com>

On Mon, Jul 20, 2015 at 7:10 PM, Gavin Andresen via bitcoin-dev
<bitcoin-dev@lists.linuxfoundation.org> wrote:
> Mitigate a potential CPU exhaustion denial-of-service attack by limiting
> the maximum size of a transaction included in a block.

This seems like a fairly indirect approach. The resource being watched
for is not the size (otherwise two transactions for 200k would be
strictly worse than one 200k transactions) but the potential of N^2
costs related to repeated hashing in checksig; which this ignores.

The cost of the indirection is forclosing future applications which
involve larger signatures but have no quadratic component and are thus
fast to verify-- or requring yet another hard fork to remove the
limit, or a kludgy soft fork that splits the same data across two
"transactions" which get processed as a unit... all would be
unfortunate.

Alternative 1 sounds more attractive to be for this reason as it's more direct.


  parent reply	other threads:[~2015-07-20 20:55 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-20 19:10 [bitcoin-dev] For discussion: limit transaction size to mitigate CVE-2013-2292 Gavin Andresen
2015-07-20 19:43 ` Tier Nolan
2015-07-20 20:30   ` Gavin Andresen
2015-07-20 19:58 ` Ross Nicoll
2015-07-20 20:55 ` Gregory Maxwell [this message]
2015-07-21 18:09   ` Gavin Andresen
2015-07-21 18:18     ` Jeremy Rubin
2015-07-23 15:41   ` Gavin Andresen
2015-07-24 20:59     ` Gavin Andresen
2015-07-25  0:47       ` odinn

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=CAAS2fgRBa47ye-ouV2jDe16MJFCKxYh0zF0Jw4BTwzpXVKgwOg@mail.gmail.com \
    --to=gmaxwell@gmail.com \
    --cc=bitcoin-dev@lists.linuxfoundation.org \
    --cc=gavinandresen@gmail.com \
    /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