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From: "Russell O'Connor" <roconnor@blockstream.io>
To: Mark Friedenbach <mark@friedenbach.org>,
	 Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Fast Merkle Trees
Date: Wed, 6 Sep 2017 21:59:54 -0400	[thread overview]
Message-ID: <CAMZUoKmD4v4vn9L=kdyJNk-km3XHpNVkD_tmS+SseMsf6YaVPg@mail.gmail.com> (raw)

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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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             reply	other threads:[~2017-09-07  2:00 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-07  1:59 Russell O'Connor [this message]
2017-09-07  2:20 ` [bitcoin-dev] Fast Merkle Trees Mark Friedenbach
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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