From: "Russell O'Connor" <roconnor@blockstream•io>
To: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Script Abuse Potential?
Date: Tue, 3 Jan 2017 00:04:50 -0500 [thread overview]
Message-ID: <CAMZUoKmOSj9+q-QHL==7ATRpP8b-jyjJpdEZbzXk2eFXcY6S4w@mail.gmail.com> (raw)
In-Reply-To: <6A91D4E4-750D-42C0-B593-3D5014B8A3F7@xbt.hk>
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OP_2DUP? Why not OP_3DUP?
On Mon, Jan 2, 2017 at 10:39 PM, Johnson Lau via bitcoin-dev <
bitcoin-dev@lists•linuxfoundation.org> 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
>>
>>
> _______________________________________________
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>
>
> _______________________________________________
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>
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next prev parent reply other threads:[~2017-01-03 5:05 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 [this message]
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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