From: Jeremy <jlrubin@mit•edu>
To: Johnson Lau <jl2012@xbt•hk>
Cc: bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org>,
Steve Davis <steven.charles.davis@gmail•com>
Subject: Re: [bitcoin-dev] Script Abuse Potential?
Date: Tue, 3 Jan 2017 19:13:39 -0500 [thread overview]
Message-ID: <CAD5xwhg3QeHZF1Oepo3dnCAth0EO3wCqyeT4a21gQ2uxZ5dTfQ@mail.gmail.com> (raw)
In-Reply-To: <6A91D4E4-750D-42C0-B593-3D5014B8A3F7@xbt.hk>
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Sure, was just upper bounding it anyways. Even less of a problem!
RE: OP_CAT, not as OP_CAT was specified, which is why it was disabled. As
far as I know, the elements alpha proposal to reenable a limited op_cat to
520 bytes is somewhat controversial...
--
@JeremyRubin <https://twitter.com/JeremyRubin>
<https://twitter.com/JeremyRubin>
On Mon, Jan 2, 2017 at 10:39 PM, Johnson Lau <jl2012@xbt•hk> wrote:
> No, there could only have not more than 201 opcodes in a script. So you
> may have 198 OP_2DUP at most, i.e. 198 * 520 * 2 = 206kB
>
> For OP_CAT, just check if the returned item is within the 520 bytes limit.
>
> On 3 Jan 2017, at 11:27, Jeremy via bitcoin-dev <
> bitcoin-dev@lists•linuxfoundation.org> wrote:
>
> It is an unfortunate script, but can't actually
> do
> that much
> it seems
> . The MAX_SCRIPT_ELEMENT_SIZE = 520 Bytes.
> Thus, it would seem the worst you could do with this would be to (10000-520*2)*520*2
> bytes ~=~ 10 MB.
>
> Much more concerning would be the op_dup/op_cat style bug, which under a
> similar script would certainly cause out of memory errors :)
>
>
>
> --
> @JeremyRubin <https://twitter.com/JeremyRubin>
> <https://twitter.com/JeremyRubin>
>
> On Mon, Jan 2, 2017 at 4:39 PM, Steve Davis via bitcoin-dev <
> bitcoin-dev@lists•linuxfoundation.org> wrote:
>
>> Hi all,
>>
>> Suppose someone were to use the following pk_script:
>>
>> [op_2dup, op_2dup, op_2dup, op_2dup, op_2dup, ...(to limit)...,
>> op_2dup, op_hash160, <addr_hash>, op_equalverify, op_checksig]
>>
>> This still seems to be valid AFAICS, and may be a potential attack vector?
>>
>> Thanks.
>>
>>
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists•linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists•linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>
>
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next prev parent reply other threads:[~2017-01-04 0:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.11263.1483391161.31141.bitcoin-dev@lists.linuxfoundation.org>
2017-01-02 21:39 ` Steve Davis
2017-01-03 3:27 ` Jeremy
2017-01-03 3:39 ` Johnson Lau
2017-01-03 5:04 ` Russell O'Connor
2017-01-04 0:13 ` Jeremy [this message]
2017-01-04 3:13 ` Russell O'Connor
2017-01-04 14:45 ` Jorge Timón
2017-01-05 16:22 ` Jeremy
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