From: Gavin Andresen <gavinandresen@gmail•com>
To: Gregory Maxwell <gmaxwell@gmail•com>
Cc: bitcoin-dev@lists•linuxfoundation.org
Subject: Re: [bitcoin-dev] For discussion: limit transaction size to mitigate CVE-2013-2292
Date: Tue, 21 Jul 2015 14:09:19 -0400 [thread overview]
Message-ID: <CABsx9T2ZX3iuCN4g6Yh0k8R7Ad0yx-yfx1f2XhCEPtz-vt2xsw@mail.gmail.com> (raw)
In-Reply-To: <CAAS2fgRBa47ye-ouV2jDe16MJFCKxYh0zF0Jw4BTwzpXVKgwOg@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1247 bytes --]
On Mon, Jul 20, 2015 at 4:55 PM, Gregory Maxwell <gmaxwell@gmail•com> wrote:
> 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.
>
Yes. The tradeoff is implementation complexity: it is trivial to check
transaction size,
not as trivial to count signature operations, because
number-of-bytes-in-transaction
doesn't require any context.
But I would REALLY hate myself if in ten years a future version of me was
struggling to
get consensus to move away from some stupid 100,000 byte transaction size
limit
I imposed to mitigate a potential DoS attack.
So I agree, a limit on sigops is the right way to go. And if that is being
changed,
might as well accurately count exactly how many sigops a transaction
actually
requires to be validated...
--
--
Gavin Andresen
[-- Attachment #2: Type: text/html, Size: 1887 bytes --]
next prev parent reply other threads:[~2015-07-21 18:09 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-20 19:10 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
2015-07-21 18:09 ` Gavin Andresen [this message]
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=CABsx9T2ZX3iuCN4g6Yh0k8R7Ad0yx-yfx1f2XhCEPtz-vt2xsw@mail.gmail.com \
--to=gavinandresen@gmail$(echo .)com \
--cc=bitcoin-dev@lists$(echo .)linuxfoundation.org \
--cc=gmaxwell@gmail$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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