đź“… Original date posted:2017-01-03
đź“ť Original message: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 at 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 at 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 at 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 at lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>
>
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Jeremy [ARCHIVE] /
npub1q8…8qwta
2023-06-07 17:55:18
in reply to nevent1q…m9a2
Author Public Key
npub1q86n5vtxkwerzwfqza3hwls8pl8764244464talfqy2vpj0qaz6q38qwtaPublished at
2023-06-07 17:55:18Event JSON
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"content": "📅 Original date posted:2017-01-03\n📝 Original message:Sure, was just upper bounding it anyways. Even less of a problem!\n\n\nRE: OP_CAT, not as OP_CAT was specified, which is why it was disabled. As\nfar as I know, the elements alpha proposal to reenable a limited op_cat to\n520 bytes is somewhat controversial...\n\n\n\n--\n@JeremyRubin \u003chttps://twitter.com/JeremyRubin\u003e\n\u003chttps://twitter.com/JeremyRubin\u003e\n\nOn Mon, Jan 2, 2017 at 10:39 PM, Johnson Lau \u003cjl2012 at xbt.hk\u003e wrote:\n\n\u003e No, there could only have not more than 201 opcodes in a script. So you\n\u003e may have 198 OP_2DUP at most, i.e. 198 * 520 * 2 = 206kB\n\u003e\n\u003e For OP_CAT, just check if the returned item is within the 520 bytes limit.\n\u003e\n\u003e On 3 Jan 2017, at 11:27, Jeremy via bitcoin-dev \u003c\n\u003e bitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\n\u003e It is an unfortunate script, but can't actually\n\u003e ​do\n\u003e that much\n\u003e ​ it seems​\n\u003e . The MAX_SCRIPT_ELEMENT_SIZE = 520 Bytes.\n\u003e ​ Thus, it would seem the worst you could do with this would be to (10000-520*2)*520*2\n\u003e bytes ~=~ 10 MB.\n\u003e\n\u003e ​Much more concerning would be the op_dup/op_cat style bug, which under a\n\u003e similar script ​would certainly cause out of memory errors :)\n\u003e\n\u003e\n\u003e\n\u003e --\n\u003e @JeremyRubin \u003chttps://twitter.com/JeremyRubin\u003e\n\u003e \u003chttps://twitter.com/JeremyRubin\u003e\n\u003e\n\u003e On Mon, Jan 2, 2017 at 4:39 PM, Steve Davis via bitcoin-dev \u003c\n\u003e bitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\n\u003e\u003e Hi all,\n\u003e\u003e\n\u003e\u003e Suppose someone were to use the following pk_script:\n\u003e\u003e\n\u003e\u003e [op_2dup, op_2dup, op_2dup, op_2dup, op_2dup, ...(to limit)...,\n\u003e\u003e op_2dup, op_hash160, \u003caddr_hash\u003e, op_equalverify, op_checksig]\n\u003e\u003e\n\u003e\u003e This still seems to be valid AFAICS, and may be a potential attack vector?\n\u003e\u003e\n\u003e\u003e Thanks.\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e _______________________________________________\n\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\n\u003e\u003e\n\u003e _______________________________________________\n\u003e bitcoin-dev mailing list\n\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\n\u003e\n\u003e\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20170103/593a2965/attachment.html\u003e",
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