[bitcoin-dev] Script Abuse Potential?

Johnson Lau jl2012 at xbt.hk
Tue Jan 3 03:39:19 UTC 2017


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 <mailto: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.
> 
> 
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