From: Mark Friedenbach <mark@friedenbach•org>
To: Russell O'Connor <roconnor@blockstream•io>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Fast Merkle Trees
Date: Wed, 6 Sep 2017 19:20:06 -0700 [thread overview]
Message-ID: <F1D041D0-FC5A-425C-835D-37E7A9C0CFC5@friedenbach.org> (raw)
In-Reply-To: <CAMZUoKmD4v4vn9L=kdyJNk-km3XHpNVkD_tmS+SseMsf6YaVPg@mail.gmail.com>
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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@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@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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next prev parent reply other threads:[~2017-09-07 2:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-07 1:59 Russell O'Connor
2017-09-07 2:20 ` Mark Friedenbach [this message]
2017-09-07 15:43 ` Russell O'Connor
2017-09-07 17:42 ` Mark Friedenbach
2017-09-07 18:55 ` Russell O'Connor
2017-09-07 20:04 ` Mark Friedenbach
2017-09-12 11:44 ` Johnson Lau
2017-09-07 5:55 ` Peter Todd
2017-09-07 15:51 ` Russell O'Connor
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