From: Johnson Lau <jl2012@xbt•hk>
To: Jeremy <jlrubin@mit•edu>,
bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org>
Cc: Steve Davis <steven.charles.davis@gmail•com>
Subject: Re: [bitcoin-dev] Script Abuse Potential?
Date: Tue, 3 Jan 2017 11:39:19 +0800 [thread overview]
Message-ID: <6A91D4E4-750D-42C0-B593-3D5014B8A3F7@xbt.hk> (raw)
In-Reply-To: <CAD5xwhjHFzFzKws10TG-XioZoRVZ_oZbMF_xDOy5xNWtzFTsEw@mail.gmail.com>
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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 <mailto: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.
>
>
> _______________________________________________
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> bitcoin-dev@lists•linuxfoundation.org <mailto:bitcoin-dev@lists•linuxfoundation.org>
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>
>
>
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next prev parent reply other threads:[~2017-01-03 3:54 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 [this message]
2017-01-03 5:04 ` Russell O'Connor
2017-01-04 0:13 ` Jeremy
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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