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Date: Tue, 3 Feb 2015 10:33:16 +0100
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From: Levin Keller <post@levinkeller.de>
To: Pavol Rusnak <stick@gk2.sk>
Content-Type: multipart/alternative; boundary=001a113a6a4ebba819050e2bc2e2
Cc: bitcoin-development@lists.sourceforge.net,
	Andreas Schildbach <andreas@schildbach.de>
Subject: Re: [Bitcoin-development] Export format for xpub
Precedence: list

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Why even bother with the specific HD scheme such as BIP32  or BIP44. What
are the interesting parameters?

Required:

   - gap limit

Optional:

   - which node of the derivation chain is actually exported (m0' for
   BIP32, m44'0'account' for BIP44)
   - which subnodes are used for external and internal purposes
   - creation date

To import the data in a read only application it is not important which
node one actually gets and in all implementations the subnode of the
exported node "0" is used for external addresses and "1" for internal
addresses.

There is no usecase to export any higher node than m0' in BIP32 or
m44'0'account' as one can only derive any child nodes of the higher nodes *with
the private master key*. As for lower nodes (like further down the path)
there is also no need to export because in all implementations today they
will only give around half of the used addresses.

So I think a more general but very useful export scheme would be:

bitcoin-pub-export:xpub[gibberish]?gaplimit=[number]&path=[path in
derivation tree]&subchains=[numbers]&creationdate=[unixtimestamp]

Why not have more descriptive parameters? Saving on data?

I am a big fan of unix timestamps. Would vote for Andreas' format on the
creation date.

Cheers

Levin

2015-02-03 1:22 GMT+01:00 Pavol Rusnak <stick@gk2.sk>:

> On 03/02/15 01:05, Andreas Schildbach wrote:
> > I don't think that parameterizing will work, we can't predict future
> > BIPs. It's the same as for BIP43, in the end we agreed on just putting
> > the BIP number.
>
> Hm, let me put the questions the other way around:
>
> What gap limit should a wallet use if it encounters h=bip32?
>
> What h value should I use for myTREZOR wallets? Which is essentially a
> BIP44 wallet that produces h=bip32 xpubs with gap limit 20 ...
>
> --
> Best Regards / S pozdravom,
>
> Pavol Rusnak <stick@gk2.sk>
>
>
> ------------------------------------------------------------------------------
> Dive into the World of Parallel Programming. The Go Parallel Website,
> sponsored by Intel and developed in partnership with Slashdot Media, is
> your
> hub for all things parallel software development, from weekly thought
> leadership blogs to news, videos, case studies, tutorials and more. Take a
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Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div><div><div><div><div>Why even bother with the specific=
 HD scheme such as BIP32=C2=A0 or BIP44. What are the interesting parameter=
s?<br><br></div><div>Required:<br></div><ul><li>gap limit</li></ul><p>Optio=
nal:</p><ul><li>which node of the derivation chain is actually exported (m0=
&#39; for BIP32, m44&#39;0&#39;account&#39; for BIP44)</li><li>which subnod=
es are used for external and internal purposes</li><li>creation date</li></=
ul>To import the data in a read only application it is not important which =
node one actually gets and in all implementations the subnode of the export=
ed node &quot;0&quot; is used for external addresses and &quot;1&quot; for =
internal addresses.<br><br></div><div>There is no usecase to export any hig=
her node than m0&#39; in BIP32 or m44&#39;0&#39;account&#39; as one can onl=
y derive any child nodes of the higher nodes <b>with the private master key=
</b>. As for lower nodes (like further down the path) there is also no need=
 to export because in all implementations today they will only give around =
half of the used addresses.<br></div><div><br>So I think a more general but=
 very useful export scheme would be:<br><br></div>bitcoin-pub-export:xpub[g=
ibberish]?gaplimit=3D[number]&amp;path=3D[path in derivation tree]&amp;subc=
hains=3D[numbers]&amp;creationdate=3D[unixtimestamp]<br><br></div><div>Why =
not have more descriptive parameters? Saving on data?<br></div><div><br></d=
iv><div></div>I am a big fan of unix timestamps. Would vote for Andreas&#39=
; format on the creation date.<br><br></div>Cheers<br><br></div>Levin<br></=
div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">2015-02-03 1:=
22 GMT+01:00 Pavol Rusnak <span dir=3D"ltr">&lt;<a href=3D"mailto:stick@gk2=
.sk" target=3D"_blank">stick@gk2.sk</a>&gt;</span>:<br><blockquote class=3D=
"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding=
-left:1ex"><span class=3D"">On 03/02/15 01:05, Andreas Schildbach wrote:<br=
>
&gt; I don&#39;t think that parameterizing will work, we can&#39;t predict =
future<br>
&gt; BIPs. It&#39;s the same as for BIP43, in the end we agreed on just put=
ting<br>
&gt; the BIP number.<br>
<br>
</span>Hm, let me put the questions the other way around:<br>
<br>
What gap limit should a wallet use if it encounters h=3Dbip32?<br>
<br>
What h value should I use for myTREZOR wallets? Which is essentially a<br>
BIP44 wallet that produces h=3Dbip32 xpubs with gap limit 20 ...<br>
<span class=3D"im HOEnZb"><br>
--<br>
Best Regards / S pozdravom,<br>
<br>
Pavol Rusnak &lt;<a href=3D"mailto:stick@gk2.sk">stick@gk2.sk</a>&gt;<br>
<br>
</span><div class=3D"HOEnZb"><div class=3D"h5">----------------------------=
--------------------------------------------------<br>
Dive into the World of Parallel Programming. The Go Parallel Website,<br>
sponsored by Intel and developed in partnership with Slashdot Media, is you=
r<br>
hub for all things parallel software development, from weekly thought<br>
leadership blogs to news, videos, case studies, tutorials and more. Take a<=
br>
look and join the conversation now. <a href=3D"http://goparallel.sourceforg=
e.net/" target=3D"_blank">http://goparallel.sourceforge.net/</a><br>
_______________________________________________<br>
Bitcoin-development mailing list<br>
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pment@lists.sourceforge.net</a><br>
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" target=3D"_blank">https://lists.sourceforge.net/lists/listinfo/bitcoin-de=
velopment</a><br>
</div></div></blockquote></div><br></div>

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