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In-Reply-To: <23C3AD3A-DB4B-4E0B-9280-2F102CA43703@arik.io>
From: Erik Aronesty <erik@q32.com>
Date: Mon, 22 Mar 2021 08:05:13 -0400
Message-ID: <CAJowKgJtF3m0-WnMYMhn=wgxk6zsmxpLuftc=nsSqCgKKX-w4Q@mail.gmail.com>
To: linuxfoundation@arik.io
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] An alternative to BIP 32?
Precedence: list

yes that would be fine.    not sure what your objection to sha3 is tho
(more provably secure) - i guess sticking with bitcoin-lib stuff tho.

On Fri, Mar 19, 2021 at 10:08 PM Arik Sosman <me@arik.io> wrote:
>
> Hi Erik,
>
> Would sha256-hmac(nonce, publicKeyPoint) still be a suitable/safe alternative without relying on sha3? That should at the very least eliminate length extension attacks.
>
> Best,
> Arik
>
> > On Mar 19, 2021, at 6:32 PM, Erik Aronesty via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
> >
> > use sha3-256.  sha256 suffers from certain attacks (length extension,
> > for example) that could make your scheme vulnerable to leaking info,
> > depending on how you concatenate things, etc.  better to choose
> > something where padding doesn't matter.
> >
> > On Fri, Mar 19, 2021 at 7:28 PM vjudeu via bitcoin-dev
> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
> >>
> >> I recently found some interesting and simple HD wallet design here: https://bitcointalk.org/index.php?topic=5321992.0
> >> Could anyone see any flaws in such design or is it safe enough to implement it and use in practice?
> >> If I understand it correctly, it is just pure ECDSA and SHA-256, nothing else:
> >>
> >> masterPublicKey = masterPrivateKey * G
> >> masterChildPublicKey = masterPublicKey + ( SHA-256( masterPublicKey || nonce ) mod n ) * G
> >> masterChildPrivateKey = masterPrivateKey + ( SHA-256( masterPublicKey || nonce ) mod n )
> >>
> >> Also, it has some nice properties, like all keys starting with 02 prefix and allows potentially unlimited custom derivation path by using 256-bit nonce.
> >> _______________________________________________
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> >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
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> > bitcoin-dev@lists.linuxfoundation.org
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>