From: "Russell O'Connor" <roconnor@blockstream•io>
To: Mark Friedenbach <mark@friedenbach•org>,
Bitcoin Protocol Discussion
<bitcoin-dev@lists•linuxfoundation.org>
Subject: [bitcoin-dev] SigOps limit.
Date: Wed, 13 Sep 2017 09:24:14 -0400 [thread overview]
Message-ID: <CAMZUoKkgr-5ziDL09jkC1wOVprcZ2=jcd-PhHnSn79hcVhrrTA@mail.gmail.com> (raw)
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On Tue, Sep 12, 2017 at 3:57 PM, Mark Friedenbach via bitcoin-dev <
bitcoin-dev@lists•linuxfoundation.org> wrote:
>
> 4MB of secp256k1 signatures takes 10s to validate on my 5 year old
> laptop (125,000 signatures, ignoring public keys and other things that
> would consume space). That's much less than bad blocks that can be
> constructed using other vulnerabilities.
If there were no sigops limits, I believe the worst case block could have
closer to 1,000,000 CHECKSIG operations. Signature checks are cached so
while repeating the sequence "2DUP CHECKSIGVERIFY" does create a lot of
checksig operations, the cached values prevent a lot of work being done.
To defeat the cache one can repeat the sequence "2DUP CHECKSIG DROP
CODESEPARATOR", which will create unique signature validation requests
every 4 bytes.
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reply other threads:[~2017-09-13 13:24 UTC|newest]
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