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Date: Thu, 7 Sep 2017 01:55:57 -0400
From: Peter Todd <pete@petertodd.org>
To: "Russell O'Connor" <roconnor@blockstream.io>,
Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
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Subject: Re: [bitcoin-dev] Fast Merkle Trees
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On Wed, Sep 06, 2017 at 09:59:54PM -0400, Russell O'Connor via bitcoin-dev =
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").
Note that in general, designs should *not* create new hash functions by usi=
ng
custom IVs, but rather use bog-standard SHA256, and make a fixed first bloc=
k.
That allows unoptimised implementations to just hash a block with the second
initialization value, and optimized implementations to start with the fixed
midstate.
--=20
https://petertodd.org 'peter'[:-1]@petertodd.org
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