📅 Original date posted:2017-09-06 📝 Original message:This design purposefully ...

Mark Friedenbach [ARCHIVE] /

npub1r3s…8d0u

2023-06-07 18:05:42

in reply to nevent1q…gh2m

📅 Original date posted:2017-09-06
📝 Original message:This design purposefully does not distinguish leaf nodes from internal nodes. That way it chained invocations can be used to validate paths longer than 32 branches. Do you see a vulnerability due to this lack of distinction?

> On Sep 6, 2017, at 6:59 PM, Russell O'Connor <roconnor at blockstream.io> wrote:
>
> The fast hash for internal nodes needs to use an IV that is not the standard SHA-256 IV. Instead needs to use some other fixed value, which should itself be the SHA-256 hash of some fixed string (e.g. the string "BIP ???" or "Fash SHA-256").
>
> As it stands, I believe someone can claim a leaf node as an internal node by creating a proof that provides a phony right-hand branch claiming to have hash 0x80000..0000100 (which is really the padding value for the second half of a double SHA-256 hash).
>
> (I was schooled by Peter Todd by a similar issue in the past.)
>
>> On Wed, Sep 6, 2017 at 8:38 PM, Mark Friedenbach via bitcoin-dev <bitcoin-dev at lists.linuxfoundation.org> wrote:
>> Fast Merkle Trees
>> BIP: https://gist.github.com/maaku/41b0054de0731321d23e9da90ba4ee0a
>> Code: https://github.com/maaku/bitcoin/tree/fast-merkle-tree
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2023-06-07 18:05:42

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